Thursday, May 31, 2012

West Bridgford Transition AGM

30 May 2012: The West Bridgford Transition group had an AGM and 4th birthday party at Belle and Jerome on 30 May. There's a more detailed summary on the WB-Transition website and on the Facebook page. I hope we can add a more detailed record when the group scribe has written it.
See the pages below for a longer report:
If you're on Facebook, please visit the page and click 'Like'
A couple of weeks ago, we had the Summer Gathering and several people signed up at the Transition stand to visit three houses, Peveril, Harms and Holt house, as examples of eco-retrofit insulation and/or technology. 

The Transition movement addresses many different aspects of transition into the low energy future. Lifestyle, transport, gardening, localism, energy efficiency are all examples of this. I am involved because it's a central ethos driving me to do this research on the Peveril Solar house.

More people turned up after this photo was taken. Thankyou Belle and Jerome for the upstairs room.

Wednesday, May 30, 2012

Planting seeds in the vegetable garden

30 May 2012: Now that the warm weather has arrived, we can all think of outdoors and doing something about the garden. Chelsea Garden Show has been on during the week, and makes me wonder how these people prepare everything so early and in spite of the very cold late spring.
    All the seeds I planted earlier in April or early May were killed off by late frosts. The heatwave turned the ground to concrete, so these are being kept moist with stored rainwater.

The string lines enable me to know precisely where to trickle the water in case the drought continues, and my rainwater store is running short. It also stops the cat using that particular zone for scratching!

Solar mirror becomes shader

30 May 2012: This hinged mirror-reflector above the window below may not be here much longer if we build a house extension. For the moment it's doing a good job of shading the dining room window from midday sun.
   The mirror was first built in aluminium sheet, but this tarnished to matt grey, so it was resurfaces in Mylar.
   The sunbox above has an internal mirror on the sloping floor that is coated in Mylar, and reflects high angled sunshine up onto the black thermal collectors. The upper mirrors, top of the picture, are intended to boost winter solar capture and do nothing at high sun angles.
  The sunbox also provides solar shading in summer to the bedroom south facing windows, without affecting the view or the sunlight entry in the winter. I still have an idea to put a reflector at sill level of these, but might make it of reflective clear plastic, so that I can still look down onto the rockery.

Tuesday, May 29, 2012

Running costs and ground temperatures

29 May 2012: Ground temperatures stayed low during the very cold spring of 2012, but have risen dramatically in the final little heat wave of May 2012. The temperature is up to 13.5ºC, as warm as it ever gets in summer, usually, and may get warmer with the addition of Tubes and the cleaning of water out of the Manifold. 
Ground Temps. Sunbox was installed Mar 2012,
and the area circled is the cold spring of 2012
 Running costs for the house reflect the weather too. They sank to what may be an all time low in January 2012, but with the cold spring, and the Sunbox being out of action, it was inevitable that they would rise. However, the house annual running cost is below 5,000 kWh and the GSHP annual is below 3,000 kWh, which is what matters greatly to me! The summer has arrived, and no heating is required till October.
Running energy costs, annually.
The upturn was caused by cold spring, but the figures have levelled off.

CAD model the As-Built plumbing

29 May 2012: It is important for the research to have a 3D model of the circuit construction, as built, so I have been updating the CAD model. Here is a progress image.

This is not complete yet, I have to build the Kingspan pumping station, and the plumbing that leads to the actual tubes.
What's the point? Well it firmly defines what has been done, enables me to make clean generic illustrations without the clutter of the loft, and allows me to record any changes I make. The model is done with ArchiCAD's GDL language.

Monday, May 28, 2012

Sunbox sensor: Significant change in control

28 May 2012: This Surya system has been in place since March 2010, and it has been operated by an AKO controller since April 2010 (used a time clock for the first month). The little thermal sensor in the Sunbox has been suspended in the airspace above the black chillers, and the control has been based either on delta-T between that and the ground loop, or the absolute air temperature. Assuming that it needs some good delta-T to push through the plastic body, I set the delta-T quite high.
AKO controller and switches:
This is the range of temperatures I was getting in
March 2012, but it resulted in a major leak with such
high temperatures - probably caused by very slow
circulation as the original Solenoid valve was failing,
 and so was the pump from running dry too long.
Finally, both packed up and the system leaked.
    I have been watching the system through the recent heat wave and thought that the Sunbox possibly acts as a borehole 'cooler' if one gets the parameters wrong. If the borehole has risen to 17ºC during the hot day, and the air temperature is 25ºC, it could be harmful to be running it in the early evening. It achieves either nothing, or a negative effect.

After a couple of months with the Tubes, I realise that it is more reliable to use the actual liquid temperature in the Sunbox as the trigger. With this, I can use a much smaller Delta-T. A difference of 3 degs or 4 degs would  be quite enough. Any higher than that, and it would keep snuffing out as the colder liquid reached the position of the upper sensor.
   The pity of it is that I won't have a means of knowing the air temperature in the Sunbox. I have enjoyed seeing this for the last two years, taking pride in the rise in temperature thanks to its construction and air tightness etc. Perhaps I can get a very inexpensive thermal sensor with a display that can be positioned next to the controller.

Work needed at East Leake

28 May 2012: Ive written to my friend in East Leake to ask him to revive the system that was installed last year. There were a number of reasons why it didn't work well, but none of these are insurmountable, and none were cause by the principles of the technology. They were to do with leaks in the plumbing. With the experience gained on the problems I had with Peveril in March'12, I know what we need to do to get it working again and avoid leaks in future. 
  • Raise the Sunbox temperature sensor and tape it to the radiator directly so that it records the liquid temperature. I am also going to do this to the Peveril Sunbox, even though I will be sorry not to have a reading as to the air temperature inside.
  • Track down the leaks he had at some joints and seal those. 
  • Fit an expansion tank to allow for periods of downtime, prevent future leaks.
  • Replace solenoid valve with 1, or probably 2 in line non return valves. I have two on my circuit.
  • Put in a solar controller if he would prefer it although this is not necessary because the AKO is better.
  • Put in airlock preventers in all possible locations, even though he doesn't seem to believe in these.
  • Put in a point where it is easy to top up the liquid level (I couldn't manage without mine!)
Re: the photo showing an afternoon shadow, there's not much one can do about this (bar shifting the house), but its not a problem if you gain plenty of energy for the majority of the day.

Sharphill Sunday

27 May 2012: Sunday, it's my son's birthday, and it's the sixth day in succession of heatwave weather, with more to come. Being slightly colder in the morning with a sunny morning, we had the highest PV of the year, exceeding the 30th April. April 2012 was a terrible month for PV with a score a full 100kWh lower than with April 2011, and if it hadn't been for that day, the difference would have been a deficit of 120kWh. Even with the brilliant weather of the last week, PV score for May 2012 is also looking to be much lower than May 2011. Our May average has been 500, and today it is still below 400.
In this graph, three years are compared.
It is May 27th, do there's a bit more to come for the
current month, but it will still be below average
View of Peveril Solar house from the path leading up to Sharphill. The house is on the edge of the green belt, so we see the crops being sown and later being harvested - sometimes at night making me think that the tractors must work with GPS, since the furrows are so perfectly parallel. The house is current in a sea of brilliant yellow!

Sharphill wood is a peaceful little forest of indigenous deciduous trees that is well maintained by the 'Friends' group. This is about the right density for a native woodland in the Nottinghamshire region.
Later we went to the Derbyshire Food and Drink festival at Hardwick Hall and I managed to get some gardening done in the evening! I think I might have to mention gardening here more often, it would make a break from all this plumbing! I need somewhere to store maps of what has been planted.
Airstream caravan coffee shop at the Derbyshire Food and Drink Festival. I can't work out where the money goes to at places like this!

Sunday, May 27, 2012

May 2012 reports

For those just arrived, I do a computation of the ANNUAL performance every Sunday, by subtracting this evening's meter reading from the same one, exactly a year ago. I add the weekly report to this blog diary entry, every week.

27 May 2012: The weather has been amazing, a week of 'PV Maxima' every day, and still continuing into the week after. At last, something is being done to redress the terrible April and early May, and the metering figures have improved. The deep ground temperature has reached a level that it normally takes all summer to reach - this may be helped partially by my cleaning the water out of the manifold and sealing the manhole. I feel sad for not having done it before, as we should have done better in earlier summers with a dry manifold. I am hoping that with the extra contribution of the Tubes, we will have better performance in future.
Illustration shows a sequence of >20kWh daily PV
  • 4,954 kWh for the House and 2,948 kWh GSHP. The 'rot' has stopped, thanks to this exceptionally good week, balancing the dire conditions of most of Spring. The GSHP used only 0.90 kWh on one day, despite a running of the washing machine during the day. It would have been a massive disappointment to have gone through the 5,000 and 3,000 barriers.
  • PV annual figure has recovered slightly, to 3,269 kWh. It's tough for any set of figures to compete against the Spring of 2011 which was freakishly good weather. The PV performance has exceeded 20kWh every day of the week, including a high of >25kWh.
  • Sunbox is working well and so are the tubes. I have got used to a regular achievement of 18kWh for a day, and the Tubes are achieving 6kWh or 7kWh /day. The meter does not do decimal points, so that is probably an average of 6.5 kWh/day.
  • Ground temperature is 13.5ºC. I am actually a little disappointed, as I have seen so much thermal energy going down, and the upcoming temperature being always above 14ºC. But my strict testing conditions are always to be Midnight on a Sunday, so I have to accept that the energy moves out to fill the volume. If I tested at 8pm it would be about 14.5º. 13.5º is as high as it gets usually in midsummer. 

20 May 2012: Well the world has been full of news, but first the Peveril Metering. The May weather has continued to be as cold and miserable as the April weather. Not so much rain, but overcast most days with cold night temperatures, still below 10ºC. This weather is pushing our two main consumption figures closer to the 3,000 and 5,000 mark than I would like, and pushing down our PV and Surya solar performance too.
  • 4,949 kWh for the House and 2,946 kWh GSHP, with the recent cold weather continuing. When will the 'Winter' end? It is uncanny how difference between these two figures remain so accurately to nearly 2,000 kWh apart - This figure is for lighting, cooking and power, modified by PV.
  • PV has dropped to 3,239 kWh. It's been another overcast week, comparing badly with last year, and badly with our supreme annual figures of over 3,450 kWh a couple of months ago!
  • Sunbox is working, and I have got some figures now, and its looking good, but I need a few sunny days to know for sure. I know from past data that their annual solar capture is in the region 2,950-3070, so will not attempt to calculate precise annual figures until April 2013. The Tubes have their heat exchanger and I repositioned it to remove all possible airlocks, and that has improved things slightly, but they are still only about a fraction as good as the real Sunbox. I expect them to get 600-700 kWh in the entire year, but at the moment, it is looking like being less than that. I must start writing an article for the SET conference in Vancouver, writing up my observations so far, comparing Tubes with Sunbox.
  • Ground temperature is 11.8ºC. A drop from last week's high of 12.5º, but I expected that.
13 May 2012: 

  • 4,909 kWh for the House and 2,918 kWh GSHP, with the recent cold weather comparing badly with May 2011. However... warm weather has returned.
  • PV has dropped to 3,273 kWh. The rain of April continued a while, but we had some very high scores this week (either side of the 20kWh/day mark) and things are brightening!
  • Sunbox is working, and I have got some figures now, but am using a new meter starting from Zero for both energy and volume, so it will take time to recompile a figure for them. The Tubes have their heat exchanger and are finally working. Energy readings will take time to build up.
  • Ground temperature is 12.5ºC. Massive leap ahead with three days of sunny weather over the weekend. The Manifold manhole has been bailed out, and let's hope that the ground temp gets higher in summer.

7 May 2012: Well, the world outside continues, even if rain is dampening everything to do with solar technology. The Leveson Enquiry grinds on with both James and Rupert Murdoch testifying - amazing people at how much can be 'forgotten' or 'not told them by their staff', even when the Guardian was delivering detailed accounts. Roy Hodgson was appointed England football manager, and within a day, the tabloid press was launching headline mocking attacks on him, initially for a slight speech impediment with his pronunciation of 'R'. Obama made a lightning trip to Afghanistan to make a speech (which I thought extremely risky, and would have been better done with Skype), The French Election had its final round and Mr Hollande won (hooray), and perhaps will be able to find another way from the European orthodoxy of austerity. I wonder if Carla Bruni will leave Sarkozy now that he is no longer in the limelight (but she has a small child to care for now).
    Britain had elections for local government, and the Labour party did magnificently capturing over 800 seats, and demolishing the Tories altogether in some regions. And in Edinburgh, a man dressing in a Penguin suit as Professor Pongoo and claiming to be from another planet got more votes than the Lib Dem (another hooray). The very bad news of the week was another triumph of Boris Johnson over Ken Livingston - he seems to be a bad prospect for London - it's a big enough city to survive 4 years of Boris, but I dread his influence if he lasts for 8 years, especially on tall buildings, and the chance he might push this manic idea for moving Heathrow to Canvey Island. What else? There are plans to put anti aircraft missiles on the rooftop of London blocks of flats (ha-ha!), and Japan decided to close all its nuclear reactors (although will this increase coal burning emissions or herald a major increase in renewable energy systems? (no sick jokes about Wave energy please!). What about the Peveril Solar house?

  • 4,902 kWh for the House and 2,907 kWh GSHP, the cold weather continuing and causing a rise in the annual consumption. I hope the warm weather returns in time to keep the figures below 5,000 and 3,000.
  • PV has dropped to 3,281 kWh. This is to be expected with continuous rain in April, and last April (2011) being a very sunny month!
  • Sunbox is working, and I have got some figures now, but am using a new meter starting from Zero, so it will take time to recompile a figure for them. The Tubes have done almost nothing in this rain.
  • Ground temperature is 11.0ºC. Stability, but not climbing. The Manifold manhole is still full of water and while rain is every day, there's no point in bailing it out. This must cause a system loss.

Saturday, May 26, 2012

Further reflections on Tubes - how many?

26 May 2012:  How many tubes would it require to be a satisfactory Solar Earth Charging installation?  I am considering it for a whole house, if there was no Sunbox on the circuit. After a couple of months, I am under pressure to come up with a figure and a discussion because I have to write an article for the SET conference in Vancouver Sept 2012.

Ratio of Area to Output governed by Stasis
If I could double the number of tubes, it does not always follow that the amount of capture would be doubled also. Presently, I have 2 square metres (15 Tubes). Capture rate is governed mostly by delta-T between the tubes and the body you are transferring heat to, not just the solar energy falling on to the tubes. A tank of water could reach 65ºC, and that is where it would have to end, regardless of the amount of tubes on the roof. The controller has a parameter for highest store temperature. It's better for the tube-ends to get very hot than for the water tank to burst - so it stops. This is "Stasis".
Could we reach Stasis in the ground?
No, it is part of my ground warming theory that the ground is so infinite in size that it is impossible to reach stasis in this way. There will always be a good delta-T. The Tubes can go right up to 80ºC plus (I have seem them at over 100ºC when the loop was not cooling them), so there is no chance of stasis - the ground loop will not rise above 20º and the highest I normally get is 14º. The heat exchanger is a block of solid metal and cannot overheat. The controller is programmed to stop if the rising liquid from the ground loop is higher than 30ºC. That is still many degrees below blood temperature. The immediate volume of clay that our ground loop is 'talking to' is 3,600 cubic metres. It would need thousands of kWh to raise that even 5 degrees. Long before that, is it winter and the heat pump is pulling the energy all out again.

How many tubes would suffice?
Without Stasis, the thermal capture from doubling the tubes area could be very close to double - i.e. a one-to-one ratio, pro rata. System losses would play a small part, as the circulating temperature might be higher, but that is a matter of applying good insulation. In summer, the loft is so hot with incidental heat that there is almost no need for insulation.
   If the present 2 sqm of tubes can make 7 kWh/day, my aim for a hot summer's day would be 20kWh/day, so on that basis, I need to triple the present area to be close to that. If the roof plane could be rotated to face south, they would do less well in the morning, but they would triumph over the length of a whole day. If they were laid with the tubes vertically oriented, they are better able to track the different solar azimuths during the day, and the heat in the copper rods would rise better. So conceivably, they could merely be increased to 4sqm or 5 sqm to achieve a good result. As the tubes are scaleable, a Varisol installation can be modified after a year to add five or ten more tubes if there is space on the roof, and one feels that the system needs tuning. That is why I chose Varisol, because there is no fixed manifold. It would be handy to lay the pipes so that addition of another group of them would be less difficult.
   Tubes are still more dependent on direct sun than the Sunbox, but if they could get more like 20-25 kWh on the peak hottest days, that would suggest that 6 square metres might be the optimum amount for a house of this size, averaged over a whole year. 4 sqm facing south would be workable, but as with PV, there are Unit costs involved in any installation, so you would be better with the larger amount.

Plumbing implications
The plumbing for tubes is something easier to install (being a frequently installed product) so it looks feasible with a larger area. However, I have no doubt that it requires the addition of a Heat Exchanger. This raises the cost and might be outside the immediate regular experience of plumbers - but it is necessary. A heat exchanger is vastly cheaper and simpler to install than a water tank. It is very effective at transferring the heat from one circuit to the other. It is dry, watertight, cannot evaporate, freeze, leak or boil.
Heat exchanger provides thermal inertia, enabling the tubes to run
for more hours per day.
Water heating
If one also wanted solar water heating, it would be wrong to use the same tubes, as the temperature range is quite wrong. It would be wrong to use a potable water tank as a heat exchanger. Apart from it being rendered thermally ineffective, there is a risk of Legionnaires disease from water that is fluctuating within a 10-40ºC range. A separate installation of 2 sqm of tubes to a separate water tank would be sufficient and safe, somewhere else on the roof or wall, and the tank can be positioned to suit the convenience of the house plumbing, not the location of the tubes.

Try a Sunbox
My recent efforts have shown that the Sunbox is very effective, especially at times when the Sun is not shining. A sunbox using the swimming pool panels requires simpler plumbing and no tank or heat exchanger, and works with the simplest of controllers. Downside is that it requires the construction cost and a suitable wall surface for the construction of the polycarbonate and ETFE box. I am keen to use the ETFE front panels so see if we can push the Sunbox technology further.

Planning implications
There is almost no difficulty with installing a row of evacuated tubes on a roof, even in a conservation area, provided one asks nicely. However! a 3 cubic metre, 4 square metre Sunbox like mine is a significant addition to the appearance of the house or building. Although it can be contained within 200mm of the wall using ETFE, it is still highly visible, like a very large window.

Bear in mind for all these estimations, that every house is different with varied sizes and insulation levels and peak heating loads, and borehole are of different depths. But the Peveril Solar house is our yardstick, our means of calibrating the requirements for solar charging, for application to any other building or house.

Observation of Tubes

26 May 2012: Saturday morning: We have had a fifth day running of sunny clear weather, and more expected on Sunday. I've got used to the daily running of the Kingspan Varisol evacuated Tubes. They are doing as well as they could considering their position, orientation, angle and area.
     They are able to maintain a steady state for most of the sunny morning, with tube temperature of 23-24º, the heat exchanger at 20-22º and the incoming ground liquid at 14º. (Above, indicates the Tubes temp of 23º. Pressing the up and down button shows the other temperatures.).
     During rest periods, the controller lets the tubes continue to pick up temperature, and rests the ground loop, then mostly, both pumps run at the same time. The running time for both pumps is about 5-6 hours/day, and the amount of heat being put down is 5-7 kWh/day. Does not sound much, but the heat pump is only using 2kWh/day and drawing 4kWh/day from the ground.
    The Tubes and Sunbox together are contributing 18+6 per day, a consistent 24 kWh/day being pumped into the earthstore.

A little timing test
I tried turning the tubes controller off for a precise ten minutes. The temperature was 24ºC at the start. After 10 minutes, the controller shows that the temperature in the manifold was 44ºC, and this heat was rapidly downloaded to the heat exchanger. 

Friday, May 25, 2012

ETFE offer from Holscot!

24 May 2012: I wrote a while back about the virtues of ETFE, immensely strong and durable transparent plastic sheet. I was lucky enough to meet Holscot, the leader in the East Midlands of fabricating ETFE into frames and other structures - based in Lincolnshire. Holscot had demonstration aluminium frames with stretched and inflated sheets of ETFE.
    The product is strong enough to resist wind loads and thrown stones, and has durability so long that its ultimate life is not known - all ETFE in use since it was first introduced 30 years ago for 'glass'-houses is still in excellent condition.
   I immediately recognised that this would be the ultimate material for a sunbox. Although more expensive than polycarbonate and glass, it is cheaper than the cost of forming a glazed box with glass, but has much higher transmission. It can be double glazed, to provide insulation. More normally, it is inflated gently (like a cushion), but if thermally stretched over a frame, it will shrink tight and remain taut enough to resist domestic scale wind loads. Holscot have a Patent on the process of doing it without needing inflation.
   Examples of the use of ETFE are the Eden Centre in Cornwall, the Space Centre in Leicester, the Beijing Aquadrome, Beijing National Stadium, The Engineering Student Centre roof in my own university, the Allianz arena (where Chelsea beat Bayern Munchen last weekend, and too many more to mention. (Illustrations from Wikipedia)

This would provide the ultimate level of transparency to solar energy that I could possibly have for the Sunbox. Holscot have written to say that they are willing to provide sponsorship for the Peveril Solar project (in the form of ETFE!), recognising that this unique application of ETFE can be another proof of the benefit of using it.

   The ETFE is so transparent to energy capture that it would nearly equivalent to leaving the black collectors naked to the sun on sunny days. With the double glazing option, the low heat loss would ensure that the sunbox would continue to work in winter and night conditions. So if ever I am to make other sunboxes for ground source heat pump users, this could prove to provide the performance that justifies the investment in a sunbox and even in a GSHP in the first place. With the experience gained on the first one, it is clear that the use of ETFE for the front hinging up panel would be a clean and one-piece solution, virtually interchangeable with the triple skin polycarbonate that I used previously (and which I suspect of having sun filtering properties.)
As I shall have to have scaffolding anyway for the proposed house extension, it's going to be all part of the summer operation to make this change.

Thursday, May 24, 2012

Modification to Heat Exchanger

23 May 2012: I dropped into Screwfix for a couple more components, and now the Heat Exchanger will be more reliable. The pipe in the photo has a non-return valve which stops the liquid free running through the HX circuit when the heat pump is running but the HX not. Also, the additional airlock remover bottle means that just about every part of the circuit that I could expect to get an airlock is now protected.
  The pipe is now insulated.... and we are getting reasonable daily results from the Kingspan Tubes - 5-6-7 kWh/day for these sunny days of the end of May.
   If we could double the area of tubes, it would not automatically double the capture (because it is subject to other factors such as pump speed, delta T and more), but it would make it more acceptable. And if the tubes faced south, it would be even more effective. So perhaps 4sqm facing south could get about the kWh as the Sunbox - 14-18 kWh/day on days like this. Now that I have sorted out the plumbing requirements, I feel ready to try it for someone.

Wednesday, May 23, 2012

Summer arrived!

22 May 2012: Last weekend was so cold, it was scarves and winter jacket weather, just right for the Summer Gathering..... NOT! At lunch time on Monday 21st there was a sudden change. I went to the Uni in a winter jacket at lunchtime, and by the time the bus got to the campus, it was sunshine and getting hot suddenly. Later in the evening, it was time to change the duvet to the summer one!
   Tuesday has been the hottest day of the year so far. Temperatures rose into the high 20s, the PV was almost a maximum of over 23 kWh, and even at midnight, the air temperature was 18.9º. The Tubes had their best chance yet to show what they can do, and managed to run for all of 8 hours, gaining a magnificent 6 kWh. The Sunbox ran for 14.5 hours and gained 18 kWh. On days like this, the heat pump is almost totally asleep, so all the thermal gains are retained in the ground. But it has been a good competition, because the morning sunshine was strongly on the east roof.
   The weather was so dire in April that the PV capture was a full 100kWh less than in the previous year.

Another bit of plumbing
I added a second airlock preventer to the heat exchanger, so that both circuits should now be reliable. Also, there is too much free running around the circuit when the Heat pump is running, but the Tubes are not. So, although one was fitted originally, there is also a second 22mm check valve, to provide more resistance to the free running. I hope I fitted it the right way round!!

23 May 2012 Postscript : Another hot sunny day, and again, we get 18 kWh from the Sunbox and 6 kWh from the Tubes. I notice that the Tubes kept on working long after dark, because the air temperature was enough to warm the thermal sensor - especially if the roof tiles are warm, and are raising the microclimate above the roof surface above the wider ambient night temperature of 19º. The controller (which has a clock) was flashing a warning sign

24 May Post Postscript: 3 days running of high sunshine, and more to come! Kilowatt-hours from PV has been 23.2, 23.4, 21.0 in consecutive days with the Sunbox at 18, 18 and 20 in the same time. The Tubes have gained 6, 6, and 7 in the same three days. The deep ground temperature is going up nicely again.

Monday, May 21, 2012

Chat with Oxford Renewables

21 May 2012: I had a telephone chat with Ben Carter of Oxford Renewables, who are the UK importer of the SolarFocus swimming pool panels that I use on the Peveril Solar house. I am anxious that they should know how good these panels are, and that they should continue to import them. Perhaps they will have a link to the 'ChargingtheEarth' website.
    I don't know how many people there are with swimming pools who need them, but for Thermal Charging of the Earth, they are beating my evacuated Tubes easily! If left naked, they would only work when sunshine falls on them, but enclosed in a Sunbox, they have proved to be very worthy! Even when I had a leaky time during the sunny days of March, it was one of the plastic piping joints which leaked - I am glad to say that the four polyethylene SolarFocus panels all remained water tight!
   If anybody with a GSHP wants advice on augmentation, I would definitely use these now. At £100 a square meter, they are good value compared with other solar panels, and need a much simpler pumping and control circuit.
  The panels are made by SolarFocus in Austria. They now seem slightly different from the ones I have (which are three years old or more), but they are the same size (1 sqm) and weight (6 kg). The ones I have are 40mm inlet, with a horizontal direction top and bottom, and it's possible to get a variation on the directions of the inlet/outlet. There is a PDF on line, for more information.

Building Case Study Visit

20th May 2012: As part of the Transition/WBEcohouses effort for the Summer Gathering weekend, the Peveril Solar house was offered as a Case Study, and I had two visitors at 1pm on 20th May, and a further 3 arrived for the 2pm slot.
  Unfortunately, I forgot to take a photo! Same as in 2011!
  There seemed to be many questions and much interest, and everybody stayed until long after the one hour slot was  up! I hope that some, or one of the visitors will come back at sometime with a specific request for help on a heat pump, MVHR or PV question.
   I took a photo of the loft, to avoid having to let people up the loft ladder (with all the associated health and safety hazards), so here is a fish eye lens photo of the plumbing at the north end of the house. The end wall is not really curved! I did put large clear labels on every component just in case someone should insist on climbing up to the loft.

Sunday, May 20, 2012

Transition and Summer Gathering

19th May 2012: West Bridgford had its Summer Gathering, and Transition West Bridgford had a stand. It's a kind of green festival, held annually in the Park, next to Central Avenue.
See: for a news report.
Although the weather was cold and overcast, it stayed dry and something like 2000 people visited during the day.

The Transition stand was mostly to do with house improvement and WB Ecohouses. We were telling people about the building case study visits on the 20th and 27th May, which included the Peveril Solar house (Surya heat pump technology), the Harms house (external insulation of 1930s house) and the Holt house on 27th (extensive retro-eco-phit conversion of 1930s house). There is still a chance to sign up for this one. 

Update circuit diagram May 2012

20 May 2012: As I have nearly completed this phase of work, I thought I would update the schematic circuit diagram for May 2012. (Its not the full circuit diagram, that will take longer to draw, and would include every detail, including electrics).
I still keep thinking of tiny improvements to make, mainly in maintenance ease, ability to modify with the least amount of liquid draining, and prevention of airlocks and overheating. This certainly proves that a prototype costs more than a production model. R&D takes so long!
   For system operation I cannot think of much more to do now. For more radical effects, it would need to be more far reaching, such as having the Tubes on the South face, or the Sunbox reconstructed with ETFE, or having PVT instead of plain PV...

Friday, May 18, 2012

Re-plumbing the Heat Exchanger

17 May 2012: After a very busy day at the University, I somehow found the will-power to get up into the loft in the evening and do some serious plumbing.
    I have added another airlock remover at one of the locations where the airlock formerly happened, and I have laid the whole Heat Exchanger on its back, so that airlocks cannot happen within. The H/X has one airlock remover, but will have another soon.
   The pipes here are not insulated yet as I have to let them work for a couple of days, and observe all joints for possible leaks. At this time of the year, the delta-T is small, and insulation is not urgent.

  I notice that when the Heat Pump is working, there is still a bit of unwanted circulation through the Heat Exchanger - this is because the effort of pushing glycol 48metres below the ground is such that it is easier to push some of that around my little heat exchanger. There is already a check valve on the H/X circuit, and I can see that I shall have to add another, to double the resistance.
  The complete solution is to use a solenoid valve, but I have learnt from experience how much better it is to reduce the number of electrical parts.
  Also, it is not good to put two check valves immediately next to each other, as you could get a small airlock in the space between, and there's not enough pressure to push it out. So I will put another one above the H/X, plus a second airlock remover.

Thursday, May 17, 2012

Peveril House Open Day

16 May 2012: The West Bridgford Transition and the West Bridgford Ecohouses groups are present at the West Bridgford Summer Gathering on 19th May. This is in the Park, alongside Central Avenue. There will be a stand, some display, and a chance for people to talk about Transition. One of the things offered is the Open Day idea and two houses are offered for visits on Sunday 20th May. One is a house offering a high level of external insulation, installed in 2011. The other one is the Peveril Solar house. See:
See also, a leaflet about the Peveril Solar house.
There's a visit offered at 1pm and 2pm on the 20th May. Email if you would like to be included.

Wednesday, May 16, 2012

Tubes, Leak, Airlock and Heat Exchanger

16 May 2012: Tubes: If asked by another GSHP user, I would definitely recommend the use of these swimming pool panels in a Sunbox for low temperature collection, not a high temperature solution like Tubes. I am keeping my tubes, observing them, writing them up for papers etc. But they have proved some useful lessons, taught me a lot about plumbing, and about augmentation methods for Heat Pumps.
  The right amount of Tubes to equal the performance of the Sunbox would have to be more than double or quad of this installation. Since I got things started earlier this month, the 2sqm of Tubes have captured 16 kWh in the time that the 4sqm of Sunbox has captured 140 kWh! OK, the Tubes are on an east facing roof, but we have had a succession of days with sunny mornings, and cooler afternoons.

Leak:  I had a small leak today. I know why, it's because I have used PTFE tape for compression joints instead of plumbers putty, and you don't have to tighten them up so much - meaning easy re-assembly and re-use of olives. However, if there is a bit of tension in the pipe, it can pull out slightly, and I had about 5mm of pull-out, causing a slow overnight leak. Thanks be to the flying spaghetti monster that I remembered to place a good drip tray to catch everything - and had some spare pipe to insert in place of the previous one. It has has been corrected now with a longer section of pipe.

Airlocks:  Getting it all started again, I had to go through 'airlock' hell again. I will buy some more airlock removers to be absolutely safe - it's better than just loosening compression joints to let air out!
  It was alarming to see that in the brief time of an hour to fix this, the temperature in the Tubes manifold zoomed to 101ºC on a day that has cold air temperature and a not-particularly bright sun. Impressive, but scary. It was a relief to get the circuit working again and cool them down. It worries me that someone who didn't know how to fix this could suffer real problems in summer. It could be massively expensive to keep calling a plumber for small things.
Heat Exchanger:   David Oliver (engineer at our department) explained how the inside of a heat exchanger works. It has a more complex pathway of tunnels than I first thought. It is possible to run the heat exchanger in the upright position, but you have to flush airlocks out of it by running at high speed and pressure, initially. The safest way to use it with a slow flow rate, low pressure circuit is for it to be flat on its back with all the pipes facing upwards, like a dead beetle (above) and put bleed valves or airlock removers above it. I need to get some compression tees and some airlock bottles to make this system even more maintenance free!

Monday, May 14, 2012

Plumbing circuit update

14 May 2012: Apart from a bit of Insulation, the Plumbing seems to be completed. Insulation isn't needed at the moment as I am still checking for leaks, and the air temperature in the daytime at this time of the year in the loft is as hot as the panels! Nowhere to lose heat to!
Plumbing to the Heat exchanger and to the Tubes
Plumbing to the Surya Sunbox. Drip trays are essential
in do-it-yourself plumbing!

Ground Temperatures

13 May 2012: Since the Sunbox was built, the curve of ground temperature has been nicely smoothed, but in the recent two months, we have had two influences on the curve, causing it to flatline at 11ºC for several weeks.
   One, the Sunbox and its meter was out of action from the middle of March until very recently. Two, the weather got colder causing more heat withdrawal and less heat insertion.
   Now that things are working again and the weather is improving, the curve is also recovering. One can see from the entry of today that the ground temperature shot up to 12.5ºC, a significant recovery.

Sunday, May 13, 2012

Manifold manhole sealed

12-May 2012: The manifold has filled with rain water again as there has been rain frequently in the last week, never giving me a long enough window of time to bail it out, let it dry and then seal it up.

This dry weather break was possible on Saturday, so the photographs show the sequence.

1. The manhole bailed out till the water is below any of the working pipes.

2. Some bubble wrap floated on top of the pipes and water, so that if rainwater does get in, the water will get to a steady state temperature and lose less of its heat to the cold air.

3. The edges of the manhole and cover were well cleaned and allowed to dry. Finally, I used a sealant gun to go around the entire crack very very slowly and carefully, pumping sealant into the crack.

After a few weeks, after some prolonged rain, perhaps, I will cut the sealant and lift the manhole cover to inspect.When it rains, I will watch it, and hope that water will pond slightly before it runs away down the slope.
    If it has remained below the pipes, the problem is solved. If it has crept back up again, then its going to have to be something I live with, an undesirable system loss.

A trail of sealant laboriously squeezed into the crack. This will have to be done every time I want to lift the lid to inspect it. Will try not to do it too often.

Finally, a water test to see if it leaks. Well its clear that there is a slight tilt in the cover at the top corner, and the water does appear to run away.

Isolation switches for controllers

12 May 2012: It is annoying having the controller in the house, when the power supply to it is in the loft. There is too much going up and down the loft ladder! So I bought a 3-gang light switch and fitted it to enable the power to come from the loft, but the power to the Surya Energy meter and the power to the Kingspan solar controller to be isolated.  (The third switch is left unused for a future purpose). These will almost never need to be used, except for trouble-shooting.
  Here's hoping for sun on Sunday. The forecast suggest there will be some in the morning!

Airlock Hell solved

12 May 2012: The Kingspan controller was working correctly during a sunny Saturday morning, but the temperature on the tubes was getting higher and higher. The pumps appeared to be working, but nothing was moving round. the temperature in the tubes was getting worryingly high, and i wanted the circuit to work so that it could cool.
     I am so grateful to my Volume meters which have a little spinning wheel indicating the speed of rotation. I had 'Airlocks Hell' - there was clearly an airlock in Both systems, the Solar tubes circuit and in the circuit linking the Heat Exchanger to the ground loop.
Airlock remover has now been installed
   In my attempts to get Jason to help (by phone), it was as if he was saying I should never have started - he hasn't heard of a solar tube system that isn't a closed circuit pumped up to pressure - and I don't have one of those special pumps - the whole principle of it being connected to a complex research circuit like this is such that it will never be a totally closed system - it will need to be topped up some times, and will be at gravity pressure initially, and then re-pressurised once it is working. (unfortunately, I don't have a pro quality pressure pump.) So I have to have a high altitude top-up tank.
    I still have to pay the plumbers, but until it has worked, I have been very unhappy to pay what with being left so high and dry, with work unfinished or requiring refixing, no offer of after-sales support. Yes, it's been my risk to take on the installation of the Heat Exchanger, but I was quoted £500 for having that done - and it would not be done in the thoughtful way I want, with ball valves to be able to modify the system - so I have sunk so much into it that I must continue.
   It refused to work all morning, but I patiently went to every part of the circuit where an airlock might form, releasing air. The heat exchanger is connected with flexible tubes and watered joints, so it is easy to undo them slightly and let air out. Still didn't work.
   I then remembered two things, that the old pump, when last used was non-functioning at the slow speed. Turned it to mid speed. The other was that the direct route for the air to move to the airlock remover was through a check valve - so air had to be let out by directly unscrewing an elbow joint to free it. .... and it finally worked! - so at midday, I could go to the farmers market and coffee bar with the comforting thought that it was working.
   Later in the day, I went to Screwfix and got a Tee-joint and an airlock remover, and fitted that, for a more permanent solution to the problem. It is all working now, without leaking, so I can gradually put the insulation back on the pipes.


Friday, May 11, 2012

Rewire Kingspan controller

10 May 2012: The Kingspan controller has been re-configured to work with the Heat Exchanger. It can read three sensors and control two pumps. It needs slight rewiring as well as configuring to 'System 24'. Let's see how it works on the next sunny day.
  I am using the old pump that has run the Surya Sunbox for the last two years. I thought it had failed, but that may have been due to airlocks in the pipe. If if has failed, then it is easy to replace. 

Thursday, May 10, 2012

Vertical Farming and ETFE

9 May 2012: There was a Vertical Farming conference in the University, and I spent all day at it, with some of my students. It's very important to our Tall Building Studio, and we have had students doing vertical farming (of one sort or another) for as long as I have been doing Tall Buildings - not all of them, but it always gets chosen by a few. Some do it very well. Now that the University of Nottingham is taking a leading role in the UK in promoting the idea, we shall all be even better informed about it.
Vertical Pharmaceutical farm proposal by Rob Streather of my
Tall Building design studio, June 2011
VF does not automatically mean tall buildings, but it does accept that we need to stack growing spaces in urban locations and on rooftops to meet the demands of growing population, obtain greater productivity, and shorten food miles. The science of Hydroponics, Aquaponics, Vaquaculture, Vermiponics and the like are advancing quickly, and are being integrated in ingenious ways. Buildings are very expensive when the client is vegetables, worms or fish, so the most likely implementations of the idea are likely to be either in very light frame buildings, or by adaptation of disused factories and empty high rises.

Holscot and ETFE:
While at the conference, I met the company Holscot who are a leading R & D and manufacturer of applications of ETFE (Ethylene Tetra Fluoro Ethylene) which is strong clear plastic sheet with exceptional toughness and transparency. I wish I had used it last summer. I thought of it, but didn't feel I would be able to obtain such a small quantity or get a suitable construction detail.
  Holscot can provide double glazed panels (as in the picture) with a light aluminium frame (of any reasonable dimension), and they do not need an inflated cushion - the sheets is heat shrinkable, so will fit tightly to the frame and not require inflation (although it is better with light inflation, but they can provide that too.)
  These could almost be a direct swap with the existing front panels of the Sunbox. with something like 98% transparency, allowing maximum solar heat to fall on the black chillers. This would make the Sunbox almost as efficient in sunlight as if it was uncovered altogether.
  There will be scaffolding up for the house extension, if we ever build it! I have written to Holscot to ask for a special deal on replacement front panels.

Plumbing done on Evac Tubes

9 May 2012: For the Evacuated Tubes circuit, the Plumbing is done now, and I have to wait for a bit of Sun to spin up the pump and push liquid round to clear air bubbles etc. (there isn't a manual override on the controller that I know of).
  Thanks to the kids who winter sport on the hill behind our house (and leave their broken sleds behind), I have another drip tray, to stop more glycol leaking into the chipboard floor. It is just the perfect length, width and height!
  The insulation will have to wait until another day, as I need to see the system working first, without a leak. The valves are all open, to allow the system to refill (having been drained at the weekend), and then the two Yellow ball valves will be closed. After that, they will only ever be opened for maintenance or isolation purposes.
  The Heat Exchanger is connected with flexible pipes because I wasn't quite sure where it would finally be positioned, and there is a chance I might want to get one double the size if this one proves the principle, but is insufficient. Note that the direction of flow has to be in opposition, hence the crossover of the pipes.
  The controller will have to be re-wired and the sensors repositioned, to enable the circuit to work with the heat exchanger - because there are two pumps to control and three sensors to read.

Sunday, May 6, 2012

Plumbing in the Heat Exchanger

6 May 2012: The plumbing for the Heat Exchanger is started now, mostly using recycled pipe from previous work. The previous work was difficult to take out because the evacuated tube plumbers ran the pipe along the floor, with a drain cock actually on the floor, so draining it was a problem. There is no space for any sort of a drip tray underneath. There will be one when the replacement work is finished. 

Here are some of the components needed - including the insulated box. I shall reuse the yellow lever ball valves, to make it possible to enable or disable the heat exchanger at the simple turn of the valves, and also to link the circuit to the existing top up vessel.
Work is proceeding. The old pipes taken out, and the valves and tee pieces beginning to appear. I will complete this before deciding exactly where the HX will sit, because the link to that will be with four flexible pipe connectors. The yellow valves will remain closed "for ever" except for diagnosis, airlock removal, isolation or topping up of the liquid. The pipes are spatially separated so that they can be insulated efficiently. 

Wednesday, May 2, 2012

Controller for the Ground loop

1 May 2012: I have been researching a thermostat or controller for the ground loop for the evacuated tubes, once the heat exchanger is installed. The cost would be £100-£150 for such a thing....
   I discovered again the benefits of RTFM, 'Read the F*ing Manual", because it turns out that this existing Kingspan SC300, is able to control two pumps, and has an option, System 24, for working with a cold mass (swimming pool or ground loop) and a heat exchanger. Im glad I didn't rush to a website and buy another controller without having checked this one first.

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