Sunday, October 30, 2011

October Reports

Ground Temps up till end of october 2011.  Temp is falling
as the heating season, but it staying consistently a fraction of a
degree higher than last year and about 2 digs higher than the year before..
30 Oct 2011: So Europe has saved the Euro, Sir Jimmy Saville died and the Occupy tents are still occupying the space in front of St Paul's Cathedral. Meanwhile, I have to report the weekly meter readings. Yet again, the key parameters are all-time records, mainly because of the continuing mild weather.
  • All time Records Falling: House 5,132 kWh, GSHP 3,167 kWh, GSHP hours 1,484.
  • PV 3,379 SB clock 2,435 hrs. (close to highest ever)
  • Sunbox 3,056 kWh (best ever was 3,094). Low because GSHP activity is so low.
  • Deep ground temperature 12.5º. A year ago it was 11.8ºC.
I shall have to start keeping more serious Gas records in the light of our decision to run the pilot light, and I am surprised how much power this has used. It seems to be about 0.5 cubic metres/day, and that's going to be about 5.5 kWh/day in winter. It does help hugely to lift the temperature in a room that is normally heated by underfloor heating through a carpet (i.e. not heated much).
   There is the question of whether the new Surya-3 Sunbox performs better than the old ones is still there. I need longer to test that. When it was just sunny Summer weather, I think the new ones did better by about 7.5%. At the moment, while we are in transition to Winter working, the GSHP hasn't been half as busy as a year ago. Winter performance will be the next big test!
This is one tiny snapshot from my metering spreadsheet, showing the Weekly
summaries fromMay 2011 to the end of October. Colour highlights are used
to indicate records or days of importance.

23 Oct 2011: Well I would like to be telling you about the death of Gadaffi, the earthquake in Turkey or the subjugation of Manchester United 6-1 by their City rivals, but instead, I have to tell you about the all-time records of my Sunbox system. Again, Every parameter save one is an all-time record.
  • All time Records Falling: House 5,153 kWh, GSHP 3,187 kWh, GSHP hours 1,493.
  • All time Records Rising: PV 3,384, SB clock 2,436 hrs.
  • Close to it: Sunbox 3,074 kWh (best ever was 3,094)
  • Deep ground temperature is 12.2ºC. A year ago it was 11.9ºC.
It's important for the research that these figure are achieved without the help of any alternative heating systems. We are not using Gas for heating, or a Wood burning stove. The heat pump is the ONLY method of heating. We thinking of getting the gas fire renovated (it hasn't been used properly since 2009, and was used for only one hour in 2010, and now it doesn't come on.)
  Part of the explanation for these excellent figures lie in the PV figure - the PV capture is at an all time high, and that is abnormal, since we have no control - logically if the PV is at its highest, the amount of sunshine is partially responsible for reducing the amount of heating required. But I am expecting an elastic bounce back in the figures if we have a stiff Winter. We must have had a horrible October last year for the figures to be so good this year. If we have a mild autumn until Christmas, will the House go below 5,000 kWh and the GSHP below 3,000 kWh? That's the new target!

16 Oct 2011: I would prefer to be telling you of records elsewhere, like Wales getting to the Final of the Rugby World Cup (they didn't), or Sebastian Vettel with a record number of Grand Prix wins (fun, but an awful waste of fossil fuel)..... but life at home has to continue on.
   Yet again, every parameter except one is a best-ever record, and the one that is not (Sunbox thermal capture) is nearly so. It must be that October 2010 was a lot colder (yes, it was), helping all these figures. If the present winter continues to be mild, I can only speculate where it will end - could the house consumption go below 5,000, and the GSHP below 3,000? I doubt it very much. They have to bottom out sometime and level off. The PV is the more surprising one, because that is not affected by changes  in our lifestyle or technology adaptations. Shows that we have been having a good summer.
  • All time Records, Falling: House 5,177 kWh, GSHP 3,210 kWh, GSHP hours 1,501.
  • All time Records, Rising: PV 3,380, SB clock 2,432 hrs.
  • Close to it: Sunbox 3,077 kWh (best ever was 3,094)
  • Deep ground temperature is 12.6ºC. A year ago it was 12.0º.
One year ago, the Annual figure for the House was 6,092 kWh, and for the GSHP was 4,011 kWh. Somehow, in a year, we have managed to reduce these figures substantially. At the worst part of last winter, the GSHP annual figure rose to 4,245 kWh... terribly disappointing considering all the work I had done on the first Sunboxes.
At the moment, we have a carbon credit balance in that the Power generation of the PV exceeds the Power consumption of the GSHP by 170 kWh! This will not last, but it's nice while it does.
The Weather forecast for next week is COLD! So I am expecting the line of best-ever records to stop.

9 Oct 2011: Oh dear, you will think I am making this up, but this is more real than Theresa May's cat! Again, almost all parameters are all time records! This Thermal YoYo has to bounce back sometime, if we get a very cold spell coming up, especially if we have a very cold Spring 2012. For the moment, I am enjoying seeing the figures improve week by week. The prospects for the coming week are cloudy, but not cold, with a sunny end to the week - so the figures are likely to be better in a week's time.
  • All time Records, Falling: House 5,202 kWh, GSHP 3,238 kWh, GSHP hours 1,514.
  • All time Records, Rising: PV 3,368, SB clock 2,432 hrs,.
  • Close to it: Sunbox 3,088 kWh (best ever was 3,094)
  • Deep ground temperature is 13.1ºC. A year ago it was 12.5º.

2 October 2011: The first October weekend coincides with an autumn heatwave which is unprecedented, the hottest October day in Weather history, and September starting with our holiday and ending with 3 perfect photovoltaic bell-curves in a row! Not surprisingly, EVERYTHING is a best ever record for annual figures - highest or lowest ever!
Last three days of September
  • House meter 5,216 kWh (I never thought it could go below 5,300 but it has!)
  • GSHP meter 3,254 kWh (I never thought it could go below 3,300 but it has!)
  • (A year ago, annual was: House 6,088 kWh, GSHP 4,020 kWh)
  • GSHP annual working hours of 1,519 hrs, the lowest ever
  • PV power generating 3,354 kWh (I expected only 2,800 when it was installed, and it's 100 kWh more than the GSHP consumption)
  • Sunbox working hours 2,425 hrs, highest ever
  • Sunbox thermal storage is 3,094 kWh, the highest ever, and 123 kWh in this week alone, the highest ever, and twice the normal amount at this time of year.
  • Deep ground temperature is 13.4ºC (but I wish it had got higher after the hot week) A year ago it was 12.2º.
My question is now to imagine how it will work out in the late Autumn, because it's a fact that Autumn 2010 was much colder than usual. If Autumn 2011 is 'normal', these figures are likely to go on getting better! But having had quite a good Summer, there might be a weather backlash and another very cold Autumn. The solar capture figures so far still reassure me that the new design of Sunbox is working better.
  There is a clear 100 kWh difference between the highest ever PV (3,354) and the lowest ever GSHP figure (3,254). This is more than a typical equinox week of GSHP working (75-90 kWh), but still a fraction of a typical winter week of GSHP (120-160 kWh).

Thursday, October 27, 2011

Marital Gas Pilot

27 Oct 2011: Although we don't use the gas for heating, we have it, because the builder put it in, because he had already paid the gas board for the mains supply. We installed a gas fire in the living room. We used it a tiny bit in 2007, didn't use it at all during 2008 and 2009, and in 2010, we paid for it to have a clean and then used only 78 pence worth.
   We have a carpet in that room and the underfloor heating is very slow to respond to temperature changes. As my dear wife really finds our living room cold, I felt obliged to have the gas fire available and the damn thing needed another service - because we don't use it, the device gets clogged up and the internal battery discharges, so we are told. It's working now, and we will leave the pilot light on during the winter, so that it stays usable. I already record gas consumption once a week, so I will compute this into overall heating. As it has so far consumed only £5 pounds worth of gas in 4.5 years, this will not add up to much.

Pilot's up!
We have found with delight that the room is now warm without needing to turn the fire on. The pilot light burns quietly all the time during the evenings - it seems to be equivalent to about half a kilowatt. With the good insulation of the room and the curtains closed in the evening, there's enough heat to keep the room warm. Seriously! Although it is a balanced flue device and the emission is going outside, the metal casing of the device is hot enough to emit heat into the room, enough to make it comfortable.

Tuesday, October 25, 2011

AnafSolar presentation

AnafSolar's website, home page
25 Oct 2011: The Solar Power UK 2011 exhibition is in Birmingham and everybody solar seems to be coming. AnafSolar are an italian manufacturer of PV-Thermal panels and they invited the people they met at Ecobuild 2011 to come to a one day 'training course' in using PV-T.
   Being the first time they had presented in the UK, it was unclear whether it was a 'presentation of the concepts' or literally a 'training course' - we went with an open mind because we have read up on it beforehand and believe in the concept.
   I travelled there with David Hill of Carbon Legacy, and there were about 30 attending. Both David and I are convinced that this is a way of the future, if linked to thermal storage and GSHPs, and went determined to make this work.
   AnafSolar started in 1976 as a manufacturer of fire extinguishers and have a leading place in the Italian market for this. They fitted a large amount of PV panels on the factory roof to reduce their power consumption, and benefit from the sunshine of Pavia, Italy. They became aware that the PV panels could be 10% more efficient if cooled, and began to develop their own product using technology from the refrigeration industry.

A naf solar presentation, good product
The course was not well presented, and we only got the information when we asked good questions. However, the product sells itself to those of us who understand the technology, even if the company doesn't yet have well prepared presentations in english, with illustrations.
  A Danish guest said at one point "Let me say, that the principle benefit of PV-T has got to be in thermal storage in the ground", and that was music to my ears. I agree with him fully, you need a coolish thermal store to dump the heat into, not a hot water tank.

The idea of PV-T
PV (grey) is from a normal panel,
the thermal power (pink) is far greater on the same day.
 The heavy dotted line is showing the 10% PV power
increase in late morning and all afternoon
from the liquid cooling. 
The idea is that if a PV installation of 4kW can normally produce 3,300 kWh/yr, it would have 10% more power capture if cooled by liquid circulating during the summer months, producing perhaps 3,600-3,700 kWh in a year. That's great for the Feed in Tariff earnings. In addition, the thermal capture from such an array is about 2.5-3.0 times as much, if you have a means to store it. This is where thermal storage comes in. On my roof, I could expect to bury 7,000-8,000 kWh/year, providing the borehole with free heat, and this would be all the heat that the GSHP needs for the entire year for the entire house. the GSHP would still consume electricity, but would be working from such a warm medium that it would use even less than it does now.

  There are 'issues', such as pipe diameter into the panels, and conflict of aluminium and copper piping, but these can be met by good circuit design. There is also the requirement for smart switching and valving, as I have on my present system.
    The complexity for the installers attending is that one needs the 'Full Monty' to make it worth doing. Instead of doing PV one year, and then perhaps a solar thermal or GSHP another, the whole thing must be an integrated installation at the same time (to get the best results) - difficult to understand if you are not an expert on the entire range of technologies. Great for New-build, difficult for Retrofit.

The next direction
I had a chance to show the AnafSolar guys my research on the GSHP and Sunbox system here. What I would really like to do, is to take the PV panels off my house, replace them all with AnafSolar panels, tee them into my ground loop and monitor the result - compare with the existing sunbox.  This is the only house in the UK which is ready to go with all the infrastructure in place - the GSHP, the borehole, the plumbing system in the loft that goes directly to the borehole - and a researcher ready and willing to monitor every day the resulting energy flows.
   A major problem with this is that you can't legitimately sell on second hand PV panels. Apparently every panel is registered with OfGem, and they would show up again if installed elsewhere, disqualifying the owner from the FIT.
    The 22 180Watt panels could be used either on an off-grid installation, or I could talk to OfGem and explain that these have been taken off for research purposes to be replaced with the equivalent wattage, and would they kindly de-register the original panels. If I have the backing of my Professor, this might be possible.
  Thinking rationally, my PV roof is working so well that it's too good to disturb, so I will probably just add more panels to the South Wall. I am also considering a small house extension to the south, which could be roofed with AnafSolar panels.

Monday, October 24, 2011

PV for 2010-2011

23 Oct 2011: The PV harvest for the last year is at an all time high and this is true despite all the rude things people have said about the summer. We usually expect a lousy Winter because of the bulk of Sharp Hill - we hope to catch up during the sunny months. This year, the Summer started earlier, with an exceptionally high March, April and May, and our annual average is the highest ever.
   I run my years from the start of Winter, 1 October, the date of the original installation in 2009.

Saturday, October 22, 2011

ThermoElectric Heat Pumps!

Illustration from the Watronix website
21 Oct 2011: One of the advantages of working in a University is that you find there is always someone researching in something useful - it's a bit of luck to know the right ones and to ask the right questions.
    Having a Friday evening pint with one of my colleagues, Mark W, and randomly asking him what he is doing, I discovered he is an expert on ThermoElectric Heat Pumps - using the Peltier Effect. Used in the right way, similar devices can convert a heat difference into electrical power, rather like a motor becoming a dynamo.

Technical datasheet.
Watronix information
Wiki information HP
Wiki information Generating

Before you or I get too excited, let's look further - I have also discovered that these are very small - from a few millimetres to a postage stamp, and the largest about the size of a playing card - and quite expensive. They have only about half the COP of a vapour compression heat pump like the one we are using, even if they could be scaled up enough to heat a house. There is also no set way to deliver or extract the heat or coolth, and how to group them.
   One of the areas of Mark's research is to work out ways of doing this. Usually, a heat sink is fixed to one side and the other side is cool, to cool the interior of a piece of electronic equipment, perhaps. So this could be used for heating, if a fast moving water jacket (ground loop) was on the cold side side and a slow moving water jacket (heating circuit) was on the other. You would need an awful lot of playing cards to heat a house... :)

Veissman Technical Guide

Basic Principle of Heat Pump, in Veissman
21 Oct 2011: I have had an interesting evening discovering the range of Veissman heat pumps. I was directed to this by reading an email about the Veissman Technical Guide 9447529 - which is full of much of the most authoritative information on Heat Pumps, installation, boreholes, etc. It's a PDF and can be downloaded from the link on this page.
  I have been able to update my pages on this blog with some of the information about Borehole specification, and I feel very lucky to have discovered this. I will add it to the links on the right hand side, for future reference.
  There is also a very good reference guide on Solar thermal panels, setup, orientation, electrics, etc, in the Veissman Vitosol Technical Guide.
  Weirdly, despite the comprehensive quality of these two excellent publications, there seems no hint whatsoever of the idea of joining them together, i.e. Solar Thermal Charging of the Ground. Perhaps I ought to write to Veissman.

Friday, October 21, 2011

Poster to China

21 October 2011: Phew! Finally got the poster off to Ningbo, here is a reduced size version of it.
Here also is the Updated Powerpoint document about the installation, with most of the useful information condensed into 21 pages. 

Thursday, October 20, 2011

Turbo charge?

20 Oct 2011: Naming games
  I have been trying to think of a word for this phenomenon, and the word 'Catalytic' keeps coming to mind. In a sense this is where THREE plus ONE equals not four but SIX because the added ingredient is more than an arithmetical addition. But in Chemistry, strictly speaking, the catalyst is not part of the reaction, it is 'interfering' beneficially. So, catalyst is not the right word.
Twin boreholes with a shared warm zone. If the daytime
heat has been put down, the area around the pipes is
temporarily warmer than the greater mass around.
   However a better analogy is 'Turbo' - in which momentum accumulated just prior to it being needed is then harnessed to add extra performance - as in turbocharged car engines. There, a turbine spinning in proportion to engine speed can suddenly be diverted to supplying air at a faster rate to the engine if you put your foot down while overtaking. The KERS system in Formula One cars stored rotational momentum of braking, shortly before granting that power to the car as it accelerates out of the corner.
Seasonal difference
At the equinox time, the heat delivered on a bright sunny day is stored immediately around the borehole pipe and it is warmer than the mass around it because of the warm daytime. So for the first part of the evening heating, the GSHP does not need to reach out to the larger mass around, it can simply grab that day's heat back first.
In winter, the heat falling on the sunbox on a sunny cold day is immediately useful to the GSHP and reduces its workload in clawing heat from down below.

Renewable Heat Premium

19 Oct 2011: When we had our Heat Pump installed in 2007, we did get a small support grant to help with the cost. There are more funds available since August 2011. The Renewable Heat Premium is a new scheme, mainly for people whose primary living property (i.e. not a second home) is off the Gas grid or who elect not to use Gas. This is additional to the Renewable Heat Incentive.

In a nutshell, it's:
• £300 for Solar Thermal HW
• £850 for Air Source Heat Pump
• £1250 for Earth or Water source Heat Pump
• £950 for Biomass boiler
The scheme runs until March 2012. Better get your skates on!

It's explained on the Energy Saving Trust website:

It's also explained on the Ice Energy website, for would-be buyers of Heat Pumps, for whom there is little alternative if they live off the Gas grid unless they want to lose a fortune on Oil, or have a large supply of wood for their wood burner:

Saturday, October 15, 2011

Small disadvantage: short term borehole cooling

During October, the angle of the Sun
is almost 'straight on!' Photo taken about
1430 15 October 2011
15 Oct 2011:  I noticed that if the GSHP has been doing a heating cycle and then stops, the Sunbox system continues pumping for a while because a strong delta-T persists. There is an amount of much colder glycol still in the panels and pipes.  The cold stuff in the system has to be flushed through.
   So, temporarily, colder glycol is being pushed down than is coming up. At 5 litres/min, this takes a while as the capacity of the upper system is about 60 litres. This means that for perhaps 12 mins, there might even be a borehole cooling effect.
    Blaise warned me about this in 2010
when he analysed the first data logger readings a long time ago, but I can't see what can be done about this. It is the disadvantage of the serial 'trickle and whoosh' plumbing method. Considered overall, the advantages are too great for this to be considered important.
   If there is sunshine, the sunbox rapidly restores the normal order of things, and starts to pump liquid around which is re-warming the zone immediately around the borehole pipes, and on nice days, it is doing this in bucketful's.

Temperatures in October: Sunbox Controls

In this case, the temperature inside the Sunbox was
more than 30 degrees hotter than the ambient air!
15 Oct 2011: We are still being lucky with fine weather in October, even though it's been grey for several days last week.
   Here is a photo of the Sunbox controls, showing temperatures on a sunny but wintry Saturday.
  Morning temperatures were below 9º and rose during the day thanks to clear sunshine.
  At 3pm, while the air temp was about 14-15º, the Sunbox internal temperature was over 45º, and the liquid going down to ground was 21.4ºC. It's coming back up at about 15º, so is leaving plenty of energy down there.
  When the heating comes back on in the evening, it will find the earth at the temperature that has been going down today, so it gets its 'diurnal' boost, because the small ring of soil immediately around the pipes has had the extra quantity of heat.

Friday, October 14, 2011

PV and Sunbox competition

Yellow is the kilowatt hour PV capture
Blue is the kilowatt hour capture of the Sunbox
Red is the Degree Days, indicating heating demand in Nottingham
14 October 2011: As one of the illustrations for my paper on China, I updated this diagram. It is showing the competition between PV and Sunbox. April and October are the months when the lines cross over and the kilowatt hour earnings change places - we are now moving to a period where the Sunbox does better.
   The red line indicates the Degree Days as an index to the heating requirements. It is based on the weather records from the East Midlands Airport, nearby.
   There is a brief moment in April and October when there is a gentle peaking of the Sunbox capture. The GSHP is working because the heating season has started, but there are still a number of warm sunny days (we wish!). When the GSHP is working there is a delta-T in the system which helps to capture more heat (at a lower temperature). 

Paper for China ISLCB Oct 2011

14 Oct 2011: I managed to get my paper sent to China for the ISLCB 2011  - having missed the first deadline of 1st October, they kindly sent me an extension to 15th October.
    There is a link to the paper from the links menu, and here is the link also. I kept it to just 8 pages, including the references. The poster will come a week later.

Wednesday, October 12, 2011

Inventions take time

11th October 2011: I was tidying up my powerpoint about the Surya Sunbox project and looking at the page about the Catalytic converter. I realised that there was a similar, more dramatic precedent to the notion that normality can take decades to follow an invention or an idea - and it is nearer to my own favoured topic, that of Skyscrapers.
Home Insurance, Chicago
the first 'skyscraper'
   Elisha Otis (1811-1861) demonstrated his idea for the safety elevator (even though unsafe elevators had been around for 100 years preceding). The date of this demonstration is reported as various dates, of 1853, 54 or 55. In the demonstration, he got his assistant to cut the cable holding up the elevator, and the public could see the elevator being saved by a safety brake. He did many such demonstrations, far and wide.

  • The point he was making was that you couldn't have an Elevator unless it incorporated his ingenious safety brake. 
  • The point I am making is that you should not instal a GSHP without including Solar charging (if the soil conditions are right).

    Otis died in 1861, but the idea and his company lived on, and is still the market leader. The first safety elevators were in factories, warehouses and the growing phenomenon of Department stores.
   The usual story is that 'his elevator made skyscrapers possible'. This is an exaggerated compression of time. The first 'Tall Building' was not until a full thirty years after his demonstration - the Home Insurance Building of Chicago, by William leBaron Jenney. This was made possible by the growing pressure to make more profitable use of land and the emergence of the steel frame. The elevator was a useful tool to make the first skyscrapers acceptable, it did not generate them. The safety elevator was used in low rise buildings such as department stores and warehouses for decades before the first high-rise.
  I don't intend to do anything as dramatic as swinging an axe to prove that GSHPs can be augmented - the catalytic converter is still a very good analogy, indeed, the effect that direct solar input has had on the GSHP has been more 'catalytic' than simply a 'linear improvement' in efficiency.

Heat pumps took a long time, so did MVHR and Solar panels
I heard about heat pumps a long time ago, indeed, they have been the mechanism in a refrigerator for over a century. But it is only in the recent decade that they have taken off for domestic buildings, reversing the usual cycle, thus cooling the air or ground and heating the house. The same applies to MVHR. I first installed two MVHR systems in 1981, one of which is still working. But never heard much marketing about them from the industry in the 90s. But they are now a key technology for the Passivhaus concept. In the same way, Solar panels as we now know them were invented decades ago, but the circumstances were not right for them to become mainstream until the recent decade. 

Tuesday, October 11, 2011

Gedling reaches for the Sun!

11 Oct 2011: There's a report in the Nottingham Evening Post that is uplifting! Back in the Summer, DNC and Arash of Rushcliffe Solar did a report for Gedling Borough Council on the potential for PV in the borough - using community and leisure and depot buildings. We were a bit worried that it might go the way of the Rushcliffe proposal, into the long grass. But clearly, there are braver and nobler souls in Gedling, and the borough council have agreed to go ahead with some installations.
    The Borough Council have agreed to embark on £430,000 worth of investment in Photovoltaic panels on the roofs of depot and civic buildings, leading to an income for the borough for the next 25 years, and demonstrating their commitment to energy saving. They hope to get it done by March 2012, in time before there is a risk of the Coalition govt from changing the tariff for large installations. 

Monday, October 10, 2011

Thermal year graph

9 October 2011: My 'Thermal year' is from 1 Oct to 1 Oct (start of the heating season and the date in 2009 that the PV roof was installed) and here is an updated graph of GSHP workload against heating degree days, up till 1st October 2011. 
   • The Red line and zone is the heating requirement of the house, based on heating degree days, as recorded by the weather station at East Midlands Airport. 
   • The Blue line and zone is the demand of the GSHP in kWhs. 
The two lines are of different units but they are scalar, they are directly proportional. During the long summer of 2011, the GSHP has required no heating at all as the incidental gains were enough to warm the house on the few days that heat was needed.
   The first Sunboxes were installed in March 2010. So GSHP consumption for the period 1 Oct 2009-2010 was mostly without the help of the Sunboxes until the last month of spring. The consumption was 4,025 kWh. During the matching period 1 Oct 2010 - 1 Oct 2011, the GSHP consumption with the help of the Sunboxes was 3,265 kWh. Towards the end of this period, the boxes were taken off and replaced with the new model (although this makes no difference to the graph above, as no house heating was required.)

Saturday, October 8, 2011

Winter arrived! and London towers

The Swiss Re ('Gherkin') in the foreground,
Willis Tower in middle ground and
the 'Shard' (London Bridge Tower)
in the distance.
8 October 2011: Two days ago, I returned from a day in London, having left when it seemed to be still the 'Indian summer', and we were baking in the front seats of the coach driving south in the face of the autumnal sun.
  Amongst other things, I was able to go up to the 23rd and the 37th floors of the Heron Tower in Bishopsgate. This has some of the most wonderful views in London (until Renzo Piano's 'Shard' is completed) and a superb example of environmentally oriented design, designed by the outstanding firm of architects, Kohn Pedersen and Fox (KPF).

During the day, the climate changed to cold, and in the evening, we returned in continuous rain, and the house heating needed to be on. It has been on since. The temperatures were reaching 30ºC only a week earlier, and now we are more realistically in daytime temperatures of 13ºC and night time temps of below 10ºC.
  I am quite pleased actually. The long summer of storage has now completed, I have what seems to be a more efficient sunbox, and I can now observe this system working through another winter, and compare it, week by week, with the previous two winters.

Retrovent fitting 2

3 October 2011: Second lot of photos of the Retrovent fitting.
Retrovent front panel fitted, and just that bit of wire to tidy up, and add the switches to a location inside the cupboard. Darren in thoughtful pose. The Top hole is the extractor and the larger finned hole is a low-speed plenum. The fins can be rotated to give a direction.
Tidying up on the outside, a mastic surround to the outlet. The wall is about 10mm thicker than expected. The vents nearest the wall are the outlet, pointing downwards and outwards. The intake is the extended portion, in clear air away from the outlet.

This would be a lot better in a house using GAS as the cooking medium, because the main emissions are CO2 and Water Vapour - both of which need clearing. We are using an electric induction hob that produces a minimum of heat. None at all actually, it's done with a magnetic field in the saucepans.
    We do not have an extractor because it wasn't possible to drill through the wall directly above the hob. We have a filtering recirculator. I hope this device will be more useful when it gets much colder and the humidity of cooking needs clearing.

Retrovent fitting

3 October 2011: Photos of the installation process of the heat reclaim unit. 
 First drilling, to locate cables behind the plaster, and establish where to drill hole.
Hole being drilled, with a dust extractor to keep it tidy.
Hole drilled, now time to prepare for fixing unit.
 The heat exchange unit waiting to be fitted into the hole

Chris Wood has written asking why I bother. I am not sure myself now, although I felt more sure a while back. It is to provide fresh air in the winter months, when we have in the past opened windows while cooking. As I monitor everything daily, the record will show if there has been an improvement.

Monday, October 3, 2011

Heat Reclaim coming!

On Monday 3rd October, we are expecting the installer to arrive from EnviroVent, to instal a RetroVent unit. This is a one-room heat reclaim unit that I saw at EcoBuild back in March 2011 and which reckoned was the best of that breed.
     It will be in the combined Kitchen-Dining area of our house. The zone that is most heated in winter, with cooking, living, and a tiled floor over the underfloor heating.
     If this will reduce the heating requirement by an noticeable amount in winter, say 1-2 kWh of GSHP per day, this will add up. I will be comparing the coming season with the previous two - demonstrating the benefits of taking daily readings.

[Postscript Jan 2012: We haven't used this as much as I intended. My wife considers it a waste of money, but I find it useful when there are cooking smells or humidity levels in the air. The idea is to get dehumidification and removal of smells without having to open a window. The winter has been mild, we I cannot claim it has saved lots of heat - but no matter how much cooking was going on, or how large the crowd of people, we have not had to open a kitchen window since October. So it is working.]

Question on thermal storage

2 October 2011: I will moot a point now that perhaps will be prophetic when I look back on it, or simply expresses anxiety.... or invites comment. Looking at a the graph above, here's a number of comments.
• Realtime mode: It's clear that the Sunbox is beneficial in supporting the GSHP in winter, so we can surmise that the contribution of the Realtime mode is working.  We are successfully defrosting the deep ground in the worst part of the Winter. It never got below 10.0ºC. Also, during Summer, the hot water heating almost always makes use of the Sunboxes in Realtime, and keeps its consumption super low, compared with the previous years. This is working!
• Diurnial mode: The descent of the curve and the climb back-up in spring shows that the speed of recovery is aided by the Sunbox, working in its Diurnial mode (bright days providing top-up heat for the cold evenings) This is working!
• Interseasonal storage - I am having slight herby-jeebies, for the first time, even though this is the central pre-occupation of the whole project. The graph of ground temperature is turning down slightly even though we haven't started heating yet. I have Questions...

So, let's discuss that:
We are still in the Summer season as far as the GSHP is concerned. There was a two Cold-snap a week ago, and we had the heating on (for evening only briefly) and the ground temperature dipped slightly to 12.9ºC - a distressingly quick response to a very small demand.
    We have had a fabulously sunny week since then and the solar capture has been 123 kWh, more than twice the normal weekly capture at this time, in fact the highest ever in a week since the Sunboxes were installed. Using the same measuring method, the ground temp has returned to 13.4ºC. Nice, but could it not have gone higher after all that input? I really was hoping for a 14 !
    It seems to me that there is an autumnal downturn in the ground curve, even though the heating season hasn't started yet. Is this just a result of heat moving away from the borehole to the region around (levelling out the thermal contours) ? I recognise that with a tarmac road running north south next to the house, we are well positioned to pick up solar heat from nature, but surely, it takes decades for that heat to reach down 48 meters? The heat down there comes from all around, not just from the immediate road. Also, 123 kWh may not be very much in the context of 3,600 cubic metres of compacted dirt, but in diurnal mode, while the GSHP is running daily, this heat is very close to the borehole pipes and therefore most useful. Interseasonal heat dumping moves away from the borehole into the vastness around.
   I have estimated that Annually, we need to draw about 9,000 kWh from the ground. We help it by putting 3,000 kWh down with the Sunbox. So the greater ground and the natural forces which put heat down there are the dominant entity, the Sunbox being only a helper. From this, you would think that with the simple equation of 9k - 3k = 6k, the ground still needs to yield a large amount, 6,000 kWh. Because Sunbox heat is mostly closest to the pipe (in Diurnial and Realtime mode) the effect of the Sunbox is Realtime and Diurnal mode is greater than this simple linear approach suggests.

Sunday, October 2, 2011

September Heatwave

2 Oct 2011: The heat wave at the end of September produced 3 successive PV-Maximum days in a row. As it is after the Equinox, these averaged 13.5 kWh only per day, but it is still nice to have them. The lower harvest is due to lower sun angles and short hours of daylight. It's distressing how quickly it gets dark in the early evenings!
    The nice thing for me was that on the same three days, the Surya-3 Sunbox achieved over 20 kWh and more (63 in total).  The angle of the front face is just about perfect for this time of year.
    It says something about the summer we have had (a lot of cloudy bright conditions) that that last day that PV was close to a maximum was 14th June, and previous to that it was May 1st and 2nd!  On those PV-Max days, the previous design of Sunboxes only managed 16-17 kWh in a day. 

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