Monday, March 29, 2010

PV Harvest over 5 months

28 March 2010: As we near the end of March, it seems to have been cold, but sunnier than usual - the PV harvest is approaching 150% of what we would expect for this month.
  We started the PV in 1st October, but had a hand held unit for the first month and a bit. Then in mid November, we went over to datalogging to the SMA website, which worked for a few days, but there were problems with the data-cable to the modem which I resoldered, and by 24 Nov, we were back in business. I also kept metered records of course.
One problem with installing in September is that one sees nothing but decline for the first few months. But things are looking good now. January and Feb were depressing due to the periods of snow and heavy cloud, but the expected harvest is so small that it doesn't matter. March has been cold but with sunny days, and that is ideal for PV panels. Often during the day we see the meter indicating that there is reverse flow (it displays a "r.e.d." message)!
Month '09 Oct Nov Dec '10 Jan Feb Mar
Actual 170.60 109.30 64.40 57.30 98.60 281.30
Expect 160.00 79.00 48.00 69.0 117.0 207.0
Ratio  1.07 1.39 1.40 0.83 0.84 1.50

March figures were 50% up on expectation.

Saturday, March 27, 2010

Sunny days in March: time for gardening

27 March: I noticed today that the OWL meter (which displays the flux through the main house electricity meter) was showing 2.75 kilowatts. I rushed round the house furiously trying to find what could have been left on, this was more than a kettle or immersion heater or oven! I then realised that the meter was actually working in reverse, and the total going from our roof to the grid, minus what we were using was 2.75 kWatts. Haha! Hope we have more days like this during the summer!
   For our temperamental GSHP, we turned off the pasteurization function altogether, and I also discovered that the water tank inside the inner casing is inadequately insulated - the whole bottom panel of a 50cm diameter hot water tank is bare metal! So I used some thin super-insulation to make a disc of insulation to slide under the tank and taped it to the sides. Also insulated some of the pipes inside the unit which presently allow heat to disperse in the cabinet. Today, the water system has been quite stable, the temperature going no higher than the hysteresis range of 5º, and not losing heat once it gets to target temperature.
  I have neglected the garden for too long, as this project has preoccupied me tooooo much - my wife is beginning to think I have 'Heat-pump Aspergers'... ! And I do wish the scaffolders would come to take their stuff away so we can have a nice photo of the finished work.
    But if I am allowed to make one observation, it was that mid afternoon, when the GSHP came on to top up the house heating, the outgoing glycol temperature was 9.4º and the returning temperature was a steady 12.9º - this is higher than the ground is ever expected to get normally even after a summer's recovery time. The Surya Sunboxes had put 12 kWhrs down below by 3pm, with more sun to come for the rest of the day! So this is working!
28 March: another sunny day and time for more gardening and time spent on some forestry up in Sharp Hill wood. Went out for three hours in the afternoon, leaving the Heatpump Off and the Sunboxes On. Air temp. is still only about 9-10. On my return, tested the ground temperature (when you turn it on, the initial glycol pulled in reflects the ground temperature if you wait about 5 mins, and when it begins to go down, that is the effect of the new outgoing colder glycol.) The ground temperature was 15.0 !
  The reason for leaving it off was not just to test the ground - it is that this particular pump cannot be trusted until it has its controller replaced. After writing the paragraph above, I went down only to find that yet again, it had run amok pushing the water temperature up into the 60s, with the red panic-light showing. Rebooted, and it was calm again, saying that no heating or HW required.

Friday, March 26, 2010

Heat pump brain fever

26 March: I have been thinking back to the trail of events that led to this whole project.
  Basically we have a heatpump with a some sort of problem with its temperature management . It frequently goes into red light condition, all the green lights on, and tries to push the water temperature up, up up, up, until it shuts down with a redlight. Sometimes I watch it, going 58, 59, 60, 61, 62... . This might not occur for some days, and then it gets a chronic condition of doing it several times a day.
   The whole business of obsessive meter reading and struggling to think of ways to charge the ground began with my frustration about water temperature management over a year ago. We don't feel we can leave it on when we go out for any length of time (which risks frost damage in wintertime.) And one of my worries was about depletion of the heat down below, and wondering how to replace it.
   I have a friend, Mike Seibert, who was an architect/housebuilder who suggested that new houses should have solar panels to warm up a slab of concrete under the house, and in the same slab, the GSHP would pull the same heat out. We didn't doubt it would work, but the question was, 'how big does the concrete need to be?' This could depend on the house location, the heat loss and size of the house, and the capacity of the heatpump, and density of pipe grid.... so many variables!

So, I started out on this project. Ice Energy offered me some pipe-meshes, and I finished up with the black swimming pool panels. The sunboxes were a way to make them work with warm air as well as with sun.

    Overall I have had a lot of fun and learning, without spending too much, and the Sunboxes really are working, so now I am hunting down the next way to improve performance. Now that we are likely to be presenting the Sunboxes at the Shanghai conference, we need to isolate every variable that can confuse data monitoring. We have enough variables to deal with already such as the weather, pump speed setting, sunbox ventilation setting, etc, but at the base of all this we need one thing to be reliably constant; the Heatpump itself. We need the heatpump to respond correctly to changes of ground temperature, and achieve a better COP if the temperature improves. If it is going Amok once or twice a day and trying to heat the water temperature to pasteurisation levels (well over 60ºC) this is confusing the readings.
    I have talked to Ice Energy and they are sending an engineer next week (1st April haha, but this choice of date is a coincidence), and for now I have turned the pasteurisation function off altogether - to zero, never happen. The problem could be either of Timing (doing it too often) or of Temperature (not knowing when to stop). There is a controller (called the REGO) inside that manages the whole GSHP. Unfortunately a lot of the data such as Hours of use and Hours of Additional heat would be set to zero with a new controller, but I will record all these on the 31st March so that the adjustment can be made in the spreadsheet.

Thursday, March 25, 2010

Ecovation website

  I found a site called Ecovation which is about Eco-Renovation of buildings, and as soon as the scaffolding is removed, I shall be photographing the finished house and send the photo and the description in to Ecovation.  Ecovation is an interesting site, dedicated to people who are retrofitting or renovating existing buildings to make them more ecofriendly. It is full of case studies that might be inspiring to some of you.

3 Sept:    Hmmmm....  I think that Ecovation are purely Oxford based, as they have not replied to me. Well, we have a WEST BRIDGFORD Ecohouses website now, started by Karina Wells and Tina Holt as part of Transition West Bridgford and with the same intentions as Ecovation. There is also a good Case Study about the Peveril Solar house on the Good Energy Website.

Surya Sunboxes... why Surya?

25 March 2010: The Sunboxes have worked for a couple of weeks now.... they have developed an identity of their own. I was asked to do a write up of them for a local bulletin, so felt it was time to give them a 'brand name'.

Surya is the Hindu God of the Sun (most old religions have a male god for the Sun and a female for the Moon.). So for now, these are 'Surya Sunboxes'! I like them and I like the name.  I have many Indian student friends, so in using that name, I am also making a gesture of friendship to them.
Surya is equivalent to the Greek god Helios, and is the only 'god' that we can actually see and feel! As the Sun will be maintaining life on the planet for another few billion years (before turning into a red giant and burning the earth up), it is worthy of respect. And it minds its own business if we dance about in circles as a form of  worship.

Dependence on Surya, the Sun!
If not in ten years, then in a hundred years time, surely, houses and buildings will have to be designed to harness the sun. Can we not be sure of this? What else will there be? !! Even if renewables now cost more than gas boilers, consider the long term view and use a free heat source!
    Just 110 yrs ago, there were those who assumed that Horse drawn transport would continue to dominate and the Motorcar would be a rich man's fancy - to the extend of requiring a car to be preceded by a walking man with a red flag. How wrong that was!.... for most of the last 70 years, cars have completely dominated urban planning and reshaped the cities, and been an index for the world and national economies.
    Similarly, there were authoritative sources who thought that the world would never need more than 5 computers, and if there were more, they would never need more than 640k of memory. Thinking further, consider how the telephone, the mobile phone, broadband and personal computers have changed our way of life.
    The concept of the 'media' as existing or shaping opinion is quite recent, and now we have social networking and the internet replacing traditional broadcast media, which old fogies still despise but cannot avoid.
   We have accepted change in everything else, but it seems that in the design of houses, we are always 50 years late.

There are those climate change doubters now who say that we will be able to continue our way of life with more oil discoveries and nuclear power? What if these are wrong and that oil and nuclear do not happen? Then the SUN is what we will have - and with some investment in smart materials, we can use SUN to maintain living standards, but we shall live in a different way than the way we do now, just as we do from those in 1900 and earlier.
    In a small way now, I can see the disappointment in people's eyes when I check their house and advise that solar PV panels would not be possible (because of dormers, trees, azimuth etc). They recognise that their house is already disadvantaged in the future society of low energy. In the long term it is possibly reduced in value.
   I often get criticised because of the high embodied energy in PV - well this is paid off in about 3 years, and it will generate energy ever after.  How long will it take to pay off the cost of your car or your new kitchen? will it not continue to consume energy for many years?
   If we have to manufacture PV panels, lets do it now while other forms of energy are reasonably cheap, not make it in 20 years time when it will be too late.
   It is an unfortunate tendency to consider only the Cost of doing something Today, and do not consider the long term Cost of Not doing something Today. So buildings promoted at planning stage as 'eco' then have the eco features stripped off during construction, as a 'cost saving'. The long term energy consumption and water consumption cost is an issue for the 'tenants', so the developer thinks he can peel off the solar panels.

I am teaching, and in the recent semester, the students had to design tall buildings (skyscrapers) that require no fossil fuel heating - 60 storey residential high rises that can store enough solar thermal energy to get through the year! They can cover pumping and heat transfer costs through photovoltaic power. They are working to Passivhaus standards. To me, this is where we will have to point.

See additional articles on: Philosophy / Carbon Zero / Glossary
By the way..... why is this article the most frequently hit article on the whole blog? Is it the word or the illustration of 'Surya' ? Please leave a comment to say how you arrived.

Sunboxes work at Night!

24 March 2010: As hoped for, the sunboxes continue to work in the evening.
Usually, the air temperature in the sunboxes drops when the sun sets, and the pump turns off.
  However, there is a time later in the evening when the heatpump is working harder (for evening heating or hot water), and the temperature of the glycol circuit in the ground loop drops, and then the sunboxes come back on again to retrieve more of the warmth left earlier... or to retrieve the milder night air-temperatures we are now getting.
  This is the big benefit compared with using a pro quality flat plate panel. These are designed to deliver high temperature heat for boosting water to 50 degrees. As mine are only trying to warm the earth, they do not need short sharp high quality, they need much longer periods of low quality heat, ie warmth.... even in the middle of the night!

Wednesday, March 24, 2010

Two visitors... three points... and one good idea!

23 March: Dr Chris Wood and Blaise visited today (Chris seeing it for the first time) to ask more questions and see it working. Chris is researching heatpumps at the moment on a real site, for Roger Bullivants (specialist ground engineers), so he is interested to see where this is leading. Chris recommends we get a datalogger with more analog channels than the 5 in the DT50. The DT500 has more.
  Earlier in the day, I hinged out the front panels of the sunboxes for a final internal wash before the scaffolding comes down. If there's any dirt on the inside of the glass, it will have to stay there for eternity now! (Our window cleaner will clean the outside, monthly, with ionized water.).
  I went to Nottingham Forest in the evening, so see our team beating Crystal Palace 2-0, but got highly distracted during the second half when contemplating another idea for a dual use sunbox combined with photovoltaic. This seems to have a lot of logic. Some of the game passed me by while thoughts revolved about the side profile, the fixings, louvring, modularity etc.... suddenly we scored a second goal. Nice - three points!
  It is difficult to have PV with a high temperature thermal panel as they are incompatible. PVs like to work cool. So if a PV is the front face of a Sunbox, the black slab behind will cool the airspace behind it in hot weather, and pick up heat radiated from the back of the PV panel. Because Sunboxes are best on a wall, the front face would have to be tilted. I might try to get a thermocouple underneath our present PV panels.
   I can feel another design idea coming on! (Pictures later...)

Monday, March 22, 2010

Modify the Plumbing for summer testing...

22 March: I am already convinced that the Diurnial benefits have already been demonstrated, and now remain to be monitored, quantified and value engineered over the rest of the spring, and next winter.
    Interseasonal benefits are now the bigger research question.
   Therefore I am currently replumbing the ‘magic metre’ during this dull cloudy day, to reduce the number of valves and tees, and make it possible to measure the deep earth temperature at any time during the summer, without having to have the heatpump running – I can do this morning and evening. In effect, the loft pump will be able to circulate the entire ground loop without any effect from the GSHP or the sunboxes, and display the temperature on the controlling thermostat. It’s a 3-speed pump, so for testing, I would run it fast, to get a quicker result.
Normal mode

PS why do there seem to be two screwthreads in the world of 22mm compression plumbing?... DOH!!
It makes it so much more difficult when swapping meters, pump and valves, as it requires checking each screwthread visually, and if there is not a match, then the olive has to be squeezed off carefully to release the closing nut... if the olive won't come off, then new pipe has to be cut...  (anybody who has tried compression joint plumbing will recognise the syndrome).
 Testing mode

25 March: The plumbing is modified now, but I will have to do some very clear diagrams to stick on the wall to make it clear to anybody after me how the valves are to be arranged for  running, or testing. I also had to move all the Electrics about 100mm to the right, realising that the previous position was dangerously close to the glycol expansion bottle.
 The lever ball valves just in front of the pump are the only differences in these photos.
 The dimpled tray under the piping is actually an upturned chest freezer lid, someone was using it on the field behind the house when the snow was here, and left it after.... its perfect for catching all the glycol drips when I have to drain the system! I can buy a drip tray of almost the same size from the nearby garden centre, but it is dark green and I wouldn't easily pick up small green droplets of leaking glycol!

My suggestion for a Shanghai Abstract

There is a good chance we can get a paper on this project to the annual global conference of SET in Shanghai. The abstract has to be submitted by April 10.  I am suggesting the following, which reflects most of the thinking that has gone into it, and now that it is working, it is pretty clearly sorted out in my mind.

  • "In the world of Ground Source heatpumps, there is much discussion of the best arrangement of sourcing, comparison of boreholes with horizontal arrangements, the depth and number of boreholes, and the seasonal performance of GSHP compared with air-source. With deep boreholes, solar heat can take decades to reach the depths, and there is a risk of annually declining performance if the soil does not recover to the previous season’s temperature before the next winter. After several years, the deep soil can be permanently chilled. There is a good case for augmenting the performance of GSHP with additional sources, combining solar panels with the ground loop, to provide immediate diurnial benefits, and to increase the chance of interseasonal storage, dependent on the depth and quality of soil."
  •    "This paper presents a discussion of the viability of hybridising the GSHP to improve the coefficient of performance. An experimental rig has been constructed during winter 2009-2010 on a full size occupied house in the city of Nottingham, England. The rig augments an existing GSHP installation. For maintaining ground temperature, warmth is more useful than heat. The south facing structures collect solar heat on sunny days, bright-sky air warmth on dull days, and air warmth even during summer nights. The warmth is sent directly to the borehole, to be recovered the same day (diurnial) during winter and equinox. The collectors continue to work through the summer and are large enough to capture long term warmth to prepare for the following winter season (interseasonal). Data is being collected in real time and can be compared with previous data records - temperatures, electricity consumption, liquid flows in different parts of the system, weather and human factors. In the initial testing, the diurnial benefits have been immediately realised."
  •     "The technology for augmenting the GSHP is considerably cheaper than the original boreholes and of the GSHP itself, and once fully quantified could lead to a reduction of the number and length of boreholes, dependent on the size of the solar installation and the predicted weather statistics for the location of the building. The technology can also improve the performance of horizontal ground source diurnally."

PhD student begins on the equinox

21 March: Blaise (the PhD Student) came round for a good look at the system, and had many questions, to fully understand what I have done so far. He is a mechanical engineer, so has no problem with technical aspects of heatpumps. He has written the abstract for an article for future publication and presentation at SET, co-authored by Blaise, myself and our Professor. I have offered a revised abstract, reflecting the long thought process that has gone into this project. (see another posting here).
The evidence that this system of sunboxes works beneficially has become visible - but it will have to be quantified if it is to be presented to the Shanghai SET Conference in August 2010. (Sustainable Energy Technologies 2010).
    The first main task for Blaise will be to ascertain the COP (Coefficient of performance) of the Heatpump (without Sunbox augmentation), and then evaluate the effect of the Sunboxes. He wants to put some datalogging thermocouples inside the machine (to the evaporator and compressor). Although key temperatures are visible on the control panel, they also need a human data recorder to get results - which is very tedious.
    As we move into the summer, the emphasis will move from winter heating to summer hotwater, and the spare energy from the sunboxes will be going into the earth - so Interseasonal storage will be very important. Frequent checking of the earth temperature will be necessary.
    During his visit, the thermostat worked very well, and rather precisely on the point of sunset, the pump was turned off as the radiance from the sky dropped, and the air temperature became low enough to turn off the pump.  Later in the evening when the heatpump was heating the house (and thus cooling the glycol) the sunbox pump came on again for short while the air temperature was higher than the ground loop. The Delta-T for switching on the pump is 3.0ºC.

Thursday, March 18, 2010

March Circuit Diagram

18 March: Now that the system is up and running, here is a new Circuit Diagram, that is highly evolved from the one that was done sometime last year.
  As Blaise (PhD student) will now be taking a greater interest in it, it was important to bring this diagram up to date.
  I also have a BA student about to do an up to date SAP calculation for this house, so must send him some scaled drawings!
19 Mar: A few days ago, I thought it would be good enough to have the Cold sensor on the cold pipe in the loft, but of course, on the first warm day of the year (19th) it appeared that the temperature in the loft can be warmer in the morning than in the sunboxes! So the system would never come on.
   So in the evening I used more of my bellwire and now have the cold sensor on the ground loop just as it comes up through the floor from the underground, into the GSHP.

PhD Student on board!

18 March: I met today with Blaise, one of our PhD students, who is studying heatpumps, with a special interest in interseasonal storage, and PV-Thermal integration. He is in his third year of study, so cannot follow my project through the next three years, but can follow it up for the rest of this year, and can make good use of the data I have been recording since August 2009. It is useful for him to have a real time, full size project to measure data from. For me it is useful to move this to another level, particularly with getting him to set the datalogger successfully.
   Most of the technically oriented PhD students set up rigs of some sort to test out an idea, and this is is what my design is to me... a research rig. I don't need to do it for economic reasons, as the PV roof with the Feedin Tariff will give me free energy for as long as I stay here.... but I have so much invested in this heatpump that it has become a continuing preoccupation to find ways to make it perform better.
   I also feel confident enough with glycol plumbing that would cheerfully tackle the adding of a solar thermal panel with a water tank at some future date to preheat the HW, and save more energy - although we use so little hot water that it doesn't seem worth doing this as well.

Wednesday, March 17, 2010

Value Engineering thoughts

17 March: It would be good if this system can be repeated, more cheaply, so that the technology could be simplified and adopted. Some Value Engineering needs to be done to quantify the benefits, against the possible installation costs of a system, materials and labour. For the benefits, this are many variables depending on the existing location, eg south facing or shading, depth of existing boreholes, heat loss of the house, operating regime and existing energy costs of the occupants etc. And the benefit may not simply be in the bills - it can reduce the installation capital cost of a GSHP. If it can reduce the depth of a borehole from 100m to 50m, that is saving about 2000 pounds! It might be able to remove the borehole altogether enabling one to charge up a horizontal array of underground pipes. For installation, there is the layout of the loft, the difficulty of laying and insulating pipes through the house to the heatpump. Rightly so, there is a higher skill factor in working with glycol than your average house water supply system. There is a design cost in adapting the system to fit the house shape and orientation and complexity of layout.
   In the early days of heatpumps, they were strictly experimental, and it has taken a long time for them to be accepted as a heating system that can be widely used (we have to thank the Swedes, Austrians etc for this, it would never happen in the UK!). It could take a while with this, if the penny pinching approach was to "not bother unless the cost is lower than... "
   This "Solar-Air GSHP augmentation system" (which it might be called) must have as a basic requirement, the black panels (the cheapest part), and the metal mounting rails... the Polycarbonate, and metal framing is essential for extending its usefulness deep into the winter, to increase the Diurnial benefit (in case Interseasonal benefit is unknown or a vain hope).
  Piping can be replaced with smaller diameter or even plastic hosing. Insulation is essential to avoid condensation, and its cost is proportional the the lengths and diameters involved. The pump is essential, and the energy flowmeter is essential for testing and proving, even for a simplest installation (you would not instal a PV system without letting the customer see what was being generated - the same applies here). The differential thermostat is essential. The solenoid valve is not, although it is a minor cost. It must have a design element because every house is different - windows, overhanging roofs or nearby trees all have to be taken into account. There is scaffolding. The labour cost has to take into account the amount of climbing about in the loft by the plumber, and the construction work on the outside.
   If we find that a lot of heat escapes and doesn't get recovered, there would be no point in increasing the number of black slabs from 4 to 6, and it is clear that the thermal harvest from just 2 panels would not be enough to justify the cost of the piping, scaffolding, flowmeter, pump etc. (I talk in Twos because of the symmetry of the movement of glycol through panel - but even numbers are not essential). So the system as I have built it seems to have been a good judgement.

Neon indicator required

17 March: What I would like in the house is a couple of small Neon dashboard lamps to indicate when the pump is running or not running. Another way would be to move the whole thermostat unit into the first floor landing instead of in the loft, as it lights up a small red indicator when the relay is activated - but I don't want to separate the kit from its tidily compact location in the loft.
    The thermostat can also turn something On when it turns the pump Off, so I could have a red light for 'not working', and a green light for 'working'. Seems a better idea to run a couple of thin DC flex to a location on the landing, with two lights set into a little dashboard or panel. It would be nice to have a rotary switch on the same panel with three settings: All off, Normal working, and All on.

19 March Postscript: I have now bought the Neons from  Maplins . And I have worked out the wiring and soldered the bits that will go into a pattress box with a master override switch. It now remains to extend the wiring to a location on our first floor landing. Amber meaning that power is On, Red means that the system is Not Pumping, and Green means that is is working - like Traffic lights!

21 March Postscript: The Neon display is now installed in the Utility room next to the Heatpump and is very useful - when the HP comes on, it cools the glycol, and one will see the green light come on, and the converse in the evening, as the air temperature falls, and the HP spends some time sleeping (redlight). The neons are very delicate, and I finished up solding them all in. My attempts to use Push fit connectors failed - they are either so loose, they fall off, or they are so tight, they break the terminals. I had to open one of the neons and make a tiny delicate re-soldering to the internal circuit.

Tuesday, March 16, 2010

'Replicatability' - would I do it again?

15 Mar: Would I do it again? This big question depends on a number of points:

  • Is it only applicable to people with a GSHP and with deep boreholes? Would the diurnial benefit help those with horizontal slinkies? How do I find one of these people? How can I find another GSHP user with a borehole? (Any volunteers, please email me!)
  • Can this be done cheaper and quicker on another house, but with the same result? It's obvious that R+D, the making of the prototype always takes longer and costs more.
  • Would the benefit be cost effective? Is it only 'helping the planet' but not helping the householder?
  • Is it a technology that only I can do, or can I codify it precisely for others to follow? (including drawings and design details for the glassy boxes, in a way that Ice Energy or someone else could package up as a kit for plumbers) 
  • If starting again, wouldnt it be better to have a swimming pool sized polystyrene box or earth under the lawn or house, and store the heat in that!? So no borehole needed.
There is a new development taking place in Nottingham, a sort of  ecodevelopment in the Meadows, and I am wondering whether to ask if they would include a test system... if they have heatpumps in mind. I know the architects and the developers.
  If anybody reading this is covered by my first paragraph, please email me!

  Some Value Engineering needs to be done to quantify the benefits, against the possible installation costs of a system, materials and labour. For the benefits, this are many variables depending on the existing location, eg south facing or shading, depth of existing boreholes, heat loss of the house, operating regime and existing energy costs of the occupants etc. And the benefit may not simply be in the bills - it can reduce the installation capital cost of a GSHP. If it can reduce the depth of a borehole from 100m to 50m, that is saving about 2000 pounds! It might be able to remove the borehole altogether enabling one to charge up a horizontal array of underground pipes.

As the system works with a low cost central heating pump, it is unnecessary to use the large and expensive 28mm copper pipes. 22mm or even 15mm would work, and one could even use push fit piping if the plumbing is challenging. Also, as the pressure and temperatures are small, one could almost consider using plastic Hosing for most of the curved or difficult sections, with interface to copper where meeting the flowmeters and panels etc. and care taken to remove airlocks. This would reduce labour cost enormously.
  Condensation is not the issue I thought it would be, as the operating temperatures are higher than the heatpump uses when working only to the ground. Condensation occurs, but the pipes are not dripping wet... just lightly spotted with wet. So thinner insulation would do on the flow pipes. On the return, some insulation is essential to reduce system losses (i.e it getting cold from the low loft temperature) but as the distance travelled is small (and so is delta-T), it can be thinner than 19mm.

Thermostat puzzles

15 Mar: My most prolific writing day yet - perhaps because the system has now proven that it works (based on observation....), and the next step has to be to verify this for certain, and to consider whether it can be replicated or costed.
 I am getting to grips with the thermostat, to get it to activate the pump instead of the timeclock (allowing it to work all night on summer nights). It has a number of parameters, such as set temperature or differential temperature, cold or hot working,  and these can be selected and set.
16 Mar: With a little help from David Atkins to work out the details of these parameters - whether minus or positive, etc. and the help of an Ikea table lamp to test it out, I managed to get the thermostat working. If the air temp. in the boxes is 3ºC warmer than the glycol circuit, it will operate the pump. I hope this is a big enough gap to stop it 'hunting' (i.e. alternating on and off). There is a hysteresis of 1.0 º to deter 'hunting'.

19 Mar: I fastened the Cold sensor to the heatpump's pipe right down close to the ground, but with the HP off overnight even this position comes up to room temperature after a night. So I have lowered the Triggering temperature difference to 1.0 deg C, as first recommended by David of Ice Energy.

  Another thing I don't seem to have is an override. At the moment, in the evening, the only way I know to activate the pump manually is to pull the probe from the glassy box, put the end under my tongue and wait a while! I might devise a parallel light switch next to thermostat, if David can't think of a way to command the thermostat to turn on the relay manually.

June Postscript: Now the system is working well, the activating temperature difference is 5 degs, and also if the sunbox air temperature is 20º or above, they come on, regardless of delta-T. I have an Override switch to force the sunboxes on, and another Override to force them off. I have coloured neon indicator lights to display the condition of the system.

Datalogger ahoy!

15 Mar: The school electronics technician has lent me a Grant DT50 5-channel Datataker. I somewhat dread it as it is going to be another difficult learning curve from a formidably difficult looking manual and device, just as I am getting to grips with this differential thermostat.  There are at least 4 channels I need to record:

  • The external temperature in the shade,
  • The air temperature inside the glassy boxes
  • The Flow glycol to the panels
  • The Return from the panels.
  • (Can anyone think of a fifth?)
I am investigating more modern devices such as Wireless 4 channel dataloggers, and for this the TinyTag looks rather good. I wouldn't need to cart a PC up to the loft, or worry about serial ports etc. Dr Chris Wood thinks I should think about more temperature readings I might want to record, and maybe go for a datalogger with more channels. I think that for proof of this concept, those first four are the most essential.

Monday, March 15, 2010

Meerkat datalogging

15 Mar: My first day with the thermostat has been interesting, reading the temp. of the air in the glassy boxes. I popped a head up into the loft at 0830 and it was 12.4. By 0900 it was 21.4 and by 1020 it was 26. I left the glycol system off for the first 2 hours. With the sun coming and going ('cloudy bright') the temperature settled at about 24-26 degrees C.
    At 1100, I turned the pump on, and within a short while, the temperature in the boxes had fallen to 13.0 degrees, showing that the heat was being drawn out at a good rate (and thus cooling the air in the sunbox.)
   With the thermostat now managing it, the pump to the boxes will resume again when the air temperature in the boxes has recovered (eg sun comes out again), or when the heatpump hibernates between heating periods.

Datalogging enquiries

15 Mar: Since my loft now has a visible temperature display of the airspace in the glassy boxes, I am up and down like a meerkat, every time the sun comes out, or goes in, to see how the temperature is doing. Clearly I need a datalogger. I thought this would be very complicated with a dedicated PC, some expensive card and probes, and some specialised software. Three years ago, we were loaned something like that, but it never worked well, and it was returned.

Now, there is a technology of UBS data logging sticks that look after themselves for weeks or months, and every so often you take them out and suck all the readings into Excel. Dr Wood has been advising me on this. You can get ones with remote probes. So I might get two, one for the north side of the house for external temperatures, and one for the glassy boxes. (I do have a sensor on the roof actually, connected to the PV panels, but this datalogs to SMA's website, and I can't match the data to the data from the solar boxes.)

After a week of working, in which the experiment seems to be working (GSHP daily consumption significantly reducing), it is now worth spending more on it to check how well it is working, and to store the figures. The experiment is only worth doing if it is provable, or is repeatable. I wish I knew another GSHP owner who I could compare notes with - or even make a plan for doing a similar exercise with.
It seems to me that this idea would work even on a GSHP with horizontal slinkies if only for the diurnial benefits There would not be interseasonal benefit with horizontal pipes unless the installer builds an underground polystyrene box for the slinkies - something you can only organise with plenty of land, and planned well in advance.

Ventilate or not ventilate?

15 Mar: During the winter, it is clear that the sunboxes should remain tightly shut to build up the temperature inside. Today, the internal temperature is 26 when the sun is bright, and 20 when it is cloudy, even though the external temperature is 8. Once the pump operates, the temperature goes down to 13.0 or less - this means that decent amounts of heat are pulled into the house.
   Later in the year,  the temperature in the boxes could be lower than the outside air if heat is drawn out too quickly. Pump speed plays a part here - if running too Slow, the liquid in the panels could reach optimum temperature when they are only half way through - the rest of their passage would achieve nothing. It is running slow at the moment.
  I hope that if I run the pump Faster, the thermostat would turn the pump off earlier if the sunbox temperature falls, thus reducing the energy consumption of the pump.
   During the summer, when the air temperature is above the ground temperature, even at night, it would seem better to open the louvres top and bottom to encourage the best possible airflow over the panels, delivering an infinite quantity of air at the higher temperature.
   Once we have a datalogger going, we will see the trend in temperatures. We will try to log the amount of heat staying in the ground.
  If interseasonal storage really proves to be a failure, we would not waste the pump all summer, and would rely on diurnial benefits only. So far, my hunch that this would work has proved better than expected, so I will continue with the experiment.
    I will just have to make a judgement about when this is right. The louvres can be controlled from within the house.
  The photos show the upper tilting rooflet, and the lower louvre.

Electrical additions!

14 Mar : Over the weekend, got the Thermostat fitted, and of course, got the Danfoss solenoid valve fitted a few days earlier. Now the system is still time clock operated, but I can also get accurate temperatures - comparing the air-sun temperature in the glassy boxes, and the glycol loop temperature, to one decimal point. There's a long bellwire from this plumbing at the north end of the house to the solar panels at the south end, and the pipe sensor is attached in that little white collar just next to the flowmeter.
   The purpose of the thermostat will be to remove the time-clock and have the system activated only by the thermostat noticing the difference between the two temperatures, and turning it on when there is an advantageous difference - perhaps 5 degrees C. As these are air-panels as well as solar, they can run all night if summer nocturnal temperatures are good enough. You have to program the unit, but there's only two buttons on the front and you have to use combinations of the buttons and time intervals (eg both buttons then wait ten seconds) to program it.  I have the instructions in Spanish, French, German and English and still can't work it out!
  When it's working, the black power cable will loop into the thermostat box.
  Its beginning to dawn on me that you can flick through parameter numbers, and then somehow set a value for the one you are trying to change. I will work on it some more!

Sunday, March 14, 2010

Scaffolding will go soon!

14 Mar: Another day of cloudy bright with some long sunshine periods. Plenty of Kilowatt hours being pulled in. As the scaffolding will go soon, I am working on what I might need to do before access becomes difficult and unsafe (by ladder!)
  I hinged out the panels and gave the inside a good cleaning with a strong hose - the inside was caked with a fine layer of brick dust from some late drilling for the tilting roofs. The first hosing just moved the dust around a bit, this time, it finished a lot cleaner.
  I have known for a while that when I will have a ladder, there will be a problem keeping the panels open while I do some maintenance. I decided to build a simple set of aluminium struts that hinge down when the panels are opened - keeping the panels at a safe angle, as in the photo.
  Looking at the house from the field, it is clear that new Photovoltaics on the south wall will do very well in the mornings and middle of the day, but the hawthorn trees on the boundary will definitely affect their harvest. It puts that late installation into doubt, although the new installation will be better than our east facing roof that gets nothing much after midday. I can trim the hawthorn back a small amount.
15 Mar:   Another thing that needed doing has now been done - insulation of the return pipes from the panels on the external wall. Although the piping is short, it is contributing to system losses to leave this uninsulated in winter. I didn't bother to insulate the flow pipe as this is already cold and most of the year heat loss will be insignificant.

Saturday, March 13, 2010

System is working! Concept of 'Quality'?

Sat, Mar 13: This system must be working! Quite how much remains to be seen... but there's enough to show that it works! (in only in a diurnial way... it will take another summer and winter to discover interseasonal storage). The daily electricity consumption is noticeably less than usual.
   Yesterday (Friday) morning was a cold cloudy day, the solar panel timeclock didnt come on till 0-930, and the heatpump was on before it, at 0900 - the ground temperature was 10.2ºC which is what it recovers to over night normally at this time of year. So this is a good yardstick.
   Saturday morning started sunny, the timeclock had been set to 0900, but I didn't turn on the heatpump till 1000. So after an hour of morning working (on a day with cold air temperature of about 6) the glycol coming up from the ground in the first morning test was 12.2. A check of the meter in the loft at 1100 showed that 4 kWhrs had been buried since 0900.
  The heatpump worked for a while and got the water temperature up faster than I have seen it work before. So if the quality of the warmth it is getting has improved its performance, then we have achieved something.
  What do I mean by 'quality'? Surely heat can only be measured in quantity? Well I would say that if heat can be pulled out, but is a narrow ring of warmth and is rapidly used up within hours or minutes, that is poor 'quality'. If heat is pulled out (at the same starting temperature) but continues to deliver for many days or hours, that is good. The idea of interseasonal heating here is to put so much down that it will deliver quality warmth for many weeks.

  One thing I must complete is insulation. I can't help feeling that some of my earlier results are helped by the pipes picking up heat from the house as they go. I am gradually getting the whole way round the system, and when pipe insulation is on, the joints etc will have to be wound with bandage or foam.

Wednesday, March 10, 2010

More about ground temperatures

10 Mar: Following my observation of the difference between morning and evening ground temperature (below), my technical guru, David Atkins says that I might be a bit optimistic to think it can recover this fast. But during this 11 hour period, no heat is put down from the solar panels, and no heat is drawn up by the heatpump. So yes.... it may take a full summer (without heating) to recover to its best. But the change in over just 11 hours is worth recording regularly in future spreadsheets. It is highly significant to the research concept around which this whole project and blog is built.

     My other technical guru, Dr Chris Wood tells me that this phenomenon is quite possible, and that if I had the patience, it would be interesting to stay up all night during the 11 hour period, monitoring the rate of change.... I don't think my family would allow that! and the heatpump doesn't allow it either, as it always tries to get back to heating after the 15 mins is up.
   What I could do is have the heatpump turned off and use the Wilo-pump in the loft running all night, with a closed circuit (not going through the solar panels), then measure the temperature of that circuit every 15 mins. I can feel another plumbing complexity coming on, of which Heath Robinson would be proud.

    Chris has also mentioned to me the concept of 'Superposition of Thermal Waves' - wow! Superposition is when a phenomenon occurs because of more than one cause or one time event, and is commonly used in Geology and Biology. A simple example that links to what I am doing with my deep ground is that of throwing a pebble into a puddle, and throwing a second but differently sized one in a second later. So the ripples from one are still affected by the second. If the ripples bounce off the edges of the tank and reflect back, it gets more interesting and the ripple shape gets very complicated. If sometimes stones are dropped into the pond, and sometimes others are ejected from the pond, imagine the complexity! I can feel a photoshop diagram coming on, even as I write. We have TWO boreholes, and are alternately putting heat down and getting it out.
     In our case, we are alternating: 1. Pulling heat out during the day, 2. Putting heat down there when the sun shines, 3. Nightly incoming of surrounding warmth when the heat pump is not pulling heat out, and finally 4. Long term recovery of the earth over the summer months - when both recovery and solar thermal input is occuring - the recovery heat comes from the perimeter, and the solar thermal from the centre.

   Left to itself in summer, the ground will even out completely (like a pond after the pebbles have sunk), because the original provider of the heat, Solar heat onto the ground takes decades to get down to 48m, and rising mantle heat is too small to measure.
   If we call Warmth movement 'positive' and Coolth movement 'negative', we must have 'Rings' around our borehole pipes that are moving in or outwards, drawn by the attraction either of the borehole pipes or of the surrounding mass. And there are two boreholes 5m apart, so the rings are crossing each other in both directions. Left long enough all these rings smooth and merge.
  My mind is so boggled after all that, I need to go to B and Q or Screwfix for a quick dose of reality! :)

Morning and Evening ground temperatures

10 March: We turn our heat pump off at about 10.30pm at night and it comes on in the morning, on at 0900 or 0930, so it has 11 hours to recover every night. I notice that the ground seems to recover amazingly quickly (by absorbing heat from the surrounding cylinder of soil).

My 15 minute deep-bore evening tests are always done at about 8pm, after the ground has been giving up its heat all day - currently, these reveal a temperature of 5.8-6.2 ºC.

In the morning, if you run it, and wait about 2-3 mins, the first incoming temperature is presumably, a fair indication of the deep temperature, after which the HP starts putting out refrigerated fluid, and then the temperature goes down. In the morning, at start up, this incoming temperature after 2-3 mins is 9.8-10.2ºC.

I am resolved to start recording this on the spreadsheet, if I can remember to be there when it starts. This will help especially in the summer if we leave the solar charging panels on through the night. I shall also modify the Sunbox plumbing to make it possible to test the ground loop temperature independently of the GSHP.

A Danfoss Valve to control the drift

March 9th: (also happens to be my birthday).... I chatted to David at Ice Energy for a while, and we reckon that the resistance from the non return valve is encouraging the drift of glycol up to the solar panels at night when the heat-pump is working in the evenings. Left to its own devices this could result in Cooling the Earth in winter evenings if the night-time air temperature drops below the ground temperature.
  We can't have a manually operated regime of opening and closing valves because it should be automatic, and not be affected by human forgetfulness.

•  One answer is either to half-close some of the lever ball valves (after the pump) to create a resistance, but this would increase the workload on the loft pump for years to come, and also could result in a future user misunderstanding this, and moving the levers to open or closed. And the pump might have to be run at a higher wattage.
•  Another answer is to have laid all the pipes with 22mm copper instead of 28mm, but that would require a time machine as I can't really recycle all that 28mm piping now. That is hindsight that we could apply to a future installation - the cost would have been a fraction of the cost of 28mm. In fact, as the Wilo pump is designed for pumping central heating all over a large house, it could possibly have been in 15mm, extremely cheap and easy to lay and insulate. The nightmarish job I had of laying the copper pipes vertically through the house would have been tolerable.
•  The third answer is what I am going to use, an electrically operated valve (with a manual override). You can get ones for 2-way or 3-way, and you can get ones for Hot or Cold systems. The Honeywell is designed for hot liquid (must be more than 5ºC) and would not work in ours. The Danfoss (illustrated) is suitable for temperatures down to -10ºC (which our system would never go down to). These valves are 5 wire, which means that they take a 230V AC power supply, but also will pass power on to the pump a few seconds after they open the valve. This prevents the pump having to pump against a closed valve in case of a failure.
  Looking at the picture of the plumbing below, I have a Real Problem working out where to put it, although the Danfoss is quite happy being positioned on its side. Or I can dispense with one of the copper pipes installed to feed a future thermal battery.

Monday, March 8, 2010

Solar Charging system is now working!

8th March: The system is working! It is on a timeclock at the moment from 0930 to sunset (1730 at the moment). On its first day, it buried 17 kWhr into the ground. Without the Energy flowmeter, this experiment would be impossible to verify. 

I discovered one problem that we hadnt thought of that makes me wish I had used smaller pipes. Or it may be the non return valve represents some resistance. I presume that there is enough of a pressure drop either side of the non return valve for the liquid to find it easier to go upstairs to our panels than through the valve.
 The circuit to the panels is soooo frictionless with 28mm pipes everywhere that when the pump is turned off at night, the heatpump pump still sends liquids round the panels, the rate is about a 1/3 or 1/4 of the rate when the loft pump is going. But it will be enough to cause a problem as it is going up cold and could be returning colder still, and causing condensation. We didnt have much of a condensation problem in daytime as it was returning distinctly warmer. 
    I tried closing a lever ball valve partially, to simulate friction in the pipe, eg as if we had used only 22 or 15mm copper. It did stop the flow eventually. but it is too closed and will force the Wilo loft pump to have to work unnecessarily hard during the sunny days. If I had used 22mm or even 15mm, would this have balanced the system better so that the GSHP didnt pump up to the loft when the loft pump is off?
     I had hoped when the Wilo pump was Off, it would act as a valve, but it seems to be open circuit when off. So how can we get a valve to close the circuit when the pump is switched off? They have to be on the same electric supply, operated by the same thermostat or timeclock. Is there such a thing as a switchable closing valve that can come on and off simultaneous to the Wilo pump??

Saturday, March 6, 2010

Adding more PV panels in September

6th March 2010: I had an email from Aidan at EvoEnergy. He had been to EcoBuild and got a definitive opinion on the best option for adding three more PV panels to the south wall.
   If I do it this summer, within less than a year of the previous one, it counts as enlarging the original installation and drops the entire amount to the lower band in the Feed in Tariff. If I wait until a year after the first panels, it counts as a new installation, and the new panels would be in the lower FiT band, leaving the original ones in the top band.

Final Plumbing connection!

6th March 2010: Colin, my plumber, came round for help on the final connection. Although I could have done it, it is still wintry weather, and I just know that I would take so much longer with the heating turned off. So it is reassuring to get someone with experience and confidence.
  First task was to move the glycol bottle up to the loft and make a connection to the pipe just above the heatpump. We had that done in the first hour.
   The second task is the connections of the Flow and Return to the solar panels. That was difficult as the 3D space they occupy had the bottle in it before.
The final part for Colin and I was to refill with the mixture of Glycol, after we had first flushed parts of the upper system with water to get rid of metal swarf or bits of flux. I can see that I shall need to check the strainer several times in the next few days as bits of stuff will take time to work their way round.
  Before my departure to see Forest, we got 20 litres of Glycol in, and 20 litres of water. But it was not full.
  When Colin left, I turned on the heat-pump and it would not work. This was an electrical fault, and fortunately nothing to do with the work we had been doing. It had been going on since earlier in the week, with a persistent "MB1" fault.  It seems to trigger the immersion heater function, and causes it to double its electricity consumption.  But now, the moment you turn it on, it would turn itself off.
  After feeling a bit desperate, trying to borrow from the neighbours a temporary electric heater (till Monday) and finding that the gas fire in the sitting room is so long unused that it would not start, we discovered that there is a weekend emergency number for Ice Energy. A nice guy called Andy phoned back and helped me through the problem, and behind the font panel, I/we found an internal rotary circuit breaker switch in the GSHP that needed resetting.
   By now, it was 1630 but I still found it worth cycling down to the City Ground to see 20 mins of Nottingham Forest. The game had been soulless and goalless until then (people were already leaving), but it suddenly pepped up, and I was witness to the only goal of the game, in the 90th minute, earning Forest 3 points while rivals West Brom were beaten by QPR down in London.

 After getting back from the game, I added another 20 litres of water, making our added system to be 60 litres in all.
  Where to go now? There is a lot of monitoring to do, first to check for leaks, and then to check for condensation - before the whole lot gets hidden under a mass or insulating bandage. And then, of course to monitor the effect on performance.
  I havent fitted the thermostatic switch for the pump yet, so for the time being it will be on a timeclock, bringing it on only in the daytime after the sun has warmed up.

  I am really wondering if an air-based heatpump would have been a good idea, as there are two units either of which can more easily be swapped out when they misbehave.

Monday, March 1, 2010

Please support early adopters

1st March:
Please support Microgenerators who had the foresight and generosity to install PV panels or wind turbines earlier than July 2009, but now are penalised with a lousy feedin tariff.

Please sign the Petition to the Govt.

I nearly installed these 3 years ago, but was put off by the poor feed in tariff then. But for people who invested at a time when their main purpose was altruistic (because the return was nothing, and the capital cost was higher) this is incredibly unfair.

Popular Posts