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Author Topic: Recharging the ground  (Read 21147 times)
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« Reply #75 on: February 04, 2016, 08:38:32 PM »

Interesting reply Mike, thanks.

My system as I said runs 24/7 and has no internal thermostat, just relies on the outside sensor and some "magic" in the controller. Interesting your original set up cycled so frequently. I'm sure there are settings in my controller to prevent a restart within xx minutes of the last run, currently set to 20 mins I think.  Currently the outside temp is 7 deg C and it is running about 20 minutes every 1 1/2 hours, max flow temp is 38 deg C.  The house sits at a constant temp 24/7, though I am considering a night set back as there is a set of contacts I can easily connect a time clock to on the pump, but not sure how much, if anything that will save.

I have decided that I do need (well OK I don't need but I would like!) a heat meter more out of curiosity than anything else.

Also I note your pump only gets you DHW up to 50 deg C. This is the only niggle with my system. The heat pump controller has no setting for the maximum hot water temperature, it just gets it as hot as it can - usually around 56 deg C - which is a) a bit too hot for my liking and b) not that efficient, I suspect the CoP drops to a little over 2 when it is above 50 deg C. ( I have the auxiliary heater disabled).

1 more question, what make and size is your pump?



3.15kWpk (15xSharp ND210)/SB3000. & 3.675kWpk (15 x Suntech 245WD)/SB4000TL, 10kW GSHP driving Wirsbo underfloor heating from 1200m ground loops. 10' x 7' solar wall (experimental). Clearview 650 Wood Burning Stove. MHRV - diy retrofit. Triple glazing.
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« Reply #76 on: February 05, 2016, 10:31:00 AM »

Roger, you asked

"1 more question, what make and size is your pump? "

Kensa 10kW single phase, single compressor installed March 2013.

Kensa are just down the road from us and I am fortunate to know one or two people there. I checked with them over the frequency of cycling and was told that was quite normal.

The image below is for yesterday's heating. You can see the effect of the wood burner in the evening. We would also prefer to be a bit cooler overnight but that doesn't seem easy to control as we also like to get up to a warm bedroom. Like you, it appears that the system is at its best keeping a constant temperature.

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« Reply #77 on: October 16, 2016, 08:09:59 PM »

Good Evening All,

I think this is the most appropriate place to post this as the main query relates to recharging the ground.

The gas valve on our 14year old trusty Micromat bolier has given up the ghost and we are looking towards getting a GSHP system fitted.

One of our local specialists has been round and I’m currently waiting on a quote from them. They are recommending a CTC Ecoheat device.

I want to integrate this with the AL4720 ET panels I bought off Navitron. I bought three of these panels as they were being sold at a good price at the time (2012) although I wasn’t entirely sure whether I would use all three or not.

After discussing the best use of the ET panels with the representative who came round and following this up with background reading off the internet I see there is an add-on module (from CTC) which would allow the integration of two of these panels and would divert excess hot water back through the ground loop.

Given the discussion in this thread about the benefits of putting heat back in to the ground I can’t see there is agreement as to the benefits of this although given different ground conditions it would be impossible to have a one answer fits all solution.

On the one hand I could have what would appear to be an excess of panels in the summer but on the other hand all three panels in the depths of winter could produce more ‘hot’ water to go in to the Ecoheat ‘heat store’. As I have already paid for the panels it seems to make sense to fit all three?

As the CTC device appears to store various bits of information it may be possible to determine the value after running the system for some time?

I’d appreciate the thoughts of the forum.



1.28kW on a Lorentz ETATRACK1000 + 1.44kW/ SB3000TL-21 (FIT), 1.28kW/ SB1700 (ROO/FIT). CTC GSi12 heat pump/Ecosol/Flowbox 8010e/Gledhill ASL0085 EHS/3off Navitron 4720AL Solar ET & Immersun T1060/T1070/T1090. 3.375kW/ SMA SB3600TL-21 and a Sunny Island 4.4M-12 c/w 15.2kWh battery and a Renault Zoe.
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An unpaid Navitron volunteer who lives off-grid.

« Reply #78 on: October 16, 2016, 09:02:58 PM »

Hi Richard,
    As you know, CTE is a brilliant scientist, lecturer and inventor. He has gone all out to make this Charge the ground business work.
  Yet somehow, I think that we would have to be on the same wavelength as CTE to get the necessary satisfaction,
   That is the problem and the only way we can go on the same wavelength is to sit in on his lectures.
   Personally, I am not in a hurry. I know when i have met more than my match.
   I have already beaten the laws of physics once and luckily, did not need to supply any witnesses or affidavits .
   but pumping heat into the ground without any form of containment would be a step too far for even me.

An unpaid Navitron volunteer,who has been living off-grid,powered by wind and solar,each year better than the last one.
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« Reply #79 on: October 17, 2016, 11:27:51 AM »

Horizontal collectors are  usually between one and two metres below the ground.    The insulating effect of the ground means that it takes a few months for the air temperature to  penetrate.    Heavy rain will speed up the process.      There would probably be   little residual heat  retained  from one day to the next  so  it won't   benefit much  but  won't do any harm either.  Sixty tubes  will only produce significant surplus in sunny summer weather, the tank stores 223 litres which is a good fit for  the three panels. 

The situation is much different for vertical  collectors, they get very little heat from the surface  and  depend  more on  ground water  so they would benefit from heat returned in summer.   In North America where there are large seasonal temperature variations  most systems are used for both heating and cooling.

DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
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« Reply #80 on: October 17, 2016, 12:42:22 PM »

Horizontal collectors are  usually between one and two metres below the ground.    The insulating effect of the ground means that it takes a few months for the air temperature to  penetrate.    Heavy rain will speed up the process.
For a few years I ran soil temp sensors at 100mm, 300mm and 1000m.

Without going back to check the data in detail, my recall is:

100mm had a clear daily variation (sort of Sine curve like, but obviously not so regular!), closely tied to what was going on at the surface with little delay (just a few hours).

300mm had a clear, though moderated, daily variation, but related to what happened yesterday.

1000m had hardly any daily variation and took a week to notice a change in trend at the surface.

Heavy rain, especially after a dry period (i.e. the ground suddenly becoming wet) could have a much faster effect on the deep temperatures.

3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40°, WSW, Lat 57° 9' (Isle of Skye)
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