Ground Source Heat Pumps

Cardew

Cardew wrote: »

This thread illustrates the criticism made in the Energy Saving Trust reports, namely that the controls are too complex for many people to understand.


My wife ain't thick!(an MA plus lesser degrees) but has not the slightest interest in, or inclination to understand, technical matters.


She simply wouldn't cope with the complexities required to get the heat pump operating efficiently. On/Off, timer, and thermostat are sufficient.


That is in no way meant to be a sexist comment, I suspect the above applies to many people(male and female)!

Well the posts in the last 4 weeks, since the above was posted, have done nothing to convince my wife;)

A big vote of thanks should go to 'lovesgshp' for his input!

lovesgshp

Thanks Cardew.
To be quite honest, if the system is sized correctly and the end user is shown at start-up how to use the controls and it is set to their initial requirements, then there is very little need to make any major adjustments.
I agree with the EST that the controls are complex, but the end user should not have to make major adjustments after the install, as the installer should do the major checks there and then and stay long enough to make sure there are no problems before leaving. We allow a full day for this, start the unit up in the morning, go for a long lunch and then back to check all is working OK.
The thing that I see with some of the UK installations, is that the pump seems to be too far undersized, causing the electric heaters to operate too often. They are only meant as a back-up system, as the pump itself will normally cope adequately without their use, apart from sterilisation of the DHW system, where it will probably activate.
Problems encountered over the last 6 years, with the units I look after:
1) Temperature sensor ..... 15 mins to replace.
2) Lightning strike on house, burning out control unit ..... 1 hour to replace.
3) Power surge on trip switch, burnt out, overridden by direct connection until new switch arrived.
4) Failure of pump on ground loop circuit. Replaced pump.
5) Client turned filter valve wrong way.
6) Mouse ate through DHW sensor cable. ( twice in 15 years according to our guys)
7) This is the major one, that the filters are not cleaned or checked at least once a year. Within 3 months after start-up the first time.
8) 3 way valve sticking, as with mine and Beardy and now possibly with Patrol.
Your wife should not worry, as they are virtually a set and forget system once installed. I have a lovely relaxing time, as rarely get any calls, so that's why I can spend time on here to hopefully help others.

Patrol

Thanks for the welcome, wish I'd found this a few years back! I read the last 4-5 pages after posting so was going to check the cylinder for air and the 3 way valve but done as suggested.

Readings were on DHW.
Summer disconnect changed to 18C.

Cold side filter was clean, although this time I noticed rotating the filter 90 degrees was much harder work than it previously was.
Warm side filter had about 20% of gauze blocked, have cleaned - is about 3 years since I last checked.

Will confirm the on/off DHW readings once I see it go. Same for refrigeration sight glass.

Now, to what looks like the problem, at least to my uneducated eye.

3 way valve moves fully to B. Only moves 3/4 of way to A so need to go back to forum comments about what to do, or ask a friendly plumber if I don't understand.

I really appreciate the help here.

Patrol

& there it goes

Sight glass filled, slight bubbling for about 30 seconds then clear.

Hot water mode switched on at 47.9, quickly dropped to 47.7 and stayed there for 5 minutes using the ground loop only. Then went up to 54.5 in 10-15 minutes and switched off.

Feeling the 3 way outputs both A and B were hot under normal operation so I expect you're going to confirm I have a sticky valve too.

I'll also check the cylinder for air, probably tomorrow now.

lovesgshp

Thanks for the update. If the 3 way valve is not fully opening, then try the WD40 first. Use the I/S manual operation to check it, but you can also move it over manualy if it is possible if it sticks early.
Yes check the air in the DHW tank, as it is only a couple of minutes.
Keep me updated and hope we can resolve.
Please give me readings on heating cycle only.

Patrol

I can't give readings on heating cycle without dialling in a crazy temperature - current cut-off is 18C but sensor is showing 28C.

WD40 didn't seem to give any extra movement using the manual controls. I couldn't physically move it so removed the plastic cover at which point I realised the red indicator wasn't straight but an upside down h shapes so was as close to A as it would get.

It appears to have the full range of movement but when the DHW is on both A and B pipes get hot. Does this mean there is likely to be a fault within the 3 way valve.

lovesgshp

It does look like the valve is faulty. You should only get the DHW pipe getting hot in the A position and then a heat surge to the heating when the DHW switches over. The 10-15 mins for the hot water is indicating that the valve is not closing fully and therefore pushing heat into the heating system.
On the dhw cycle, watch the temp on GT1 and see if it increases.

lovesgshp

Patrol wrote: »

I can't give readings on heating cycle without dialling in a crazy temperature - current cut-off is 18C but sensor is showing 28C.

WD40 didn't seem to give any extra movement using the manual controls. I couldn't physically move it so removed the plastic cover at which point I realised the red indicator wasn't straight but an upside down h shapes so was as close to A as it would get.

It appears to have the full range of movement but when the DHW is on both A and B pipes get hot. Does this mean there is likely to be a fault within the 3 way valve.

Cut the room sensor influence to zero as a test for the moment and let me know what happens.

Patrol

Beardy & yourself have already helped. The valve seems to have improved and the GHSP has been idle for several hours. :beer:

My house is slowly cooling (insulated thermal mass + floor tiles).
The DHW temperature dropped by 0.4C in 1 hour. Reasonable?

Setting room influence to 0 did nothing, I'm tempted to leave at 5 until I can see whether the valve is fully operational.

Figures below are at idle, will post DHW and heating as I get them.

GT1 on 8C now 24.4C
GT2 13.8C
GT3 tgt 50c now 49.9C (to 49.5C an hour later)
GT5 tgt 18.8C now 26.1C
GT6 28.3C
GT8 24.6C
GT9 24.6C
GT10 22.3C
GT11 21.2C

Readings in 39 hours. 18 before filters & WD40, 21 after.
Loop 13950 +7 hours
Additional heat 900 +2 hours
Includes 1 DHW peak before WD40

3 bedroom thermostats all indicate 21-22C and a thermometer next to GT5 shows 23C so GT5 may be inaccurate or outside it's tolerance?

Patrol

OK, figures for this evenings DHW.
(my wife ran hot water for 2 minutes half way through before I realised)

Started at 7.03pm, completed at 7.30pm.
No additional heat.
Front panel off for first 20 minutes or so.
Valve A pipe warmed up quickly.
VAlve B pipe warmed up over 5-10 minutes.

GT1 started at on 8C now 24.4C to on 8C now 23.9C
GT2 dropped from 14.6C to 14.1C
GT3 dropped from 47.8C to 47.1C before rising to 54.3C
GT5 remained constant at 18.8C and 25.8C
GT6 started at 43.1% and reached 85% before ranging 70%-80%
GT8 started at 41.8C and rose steadily to 57.3C
GT9 started at 42.2C and rose steadily to 52.1C
GT10 started at 13.1C, dropped quickly to 9.6C then slowly to 8.9C
GT11 started at 10.2C, dropped quickly to 7.3C then slowly to 6.4C

Operating hours remained unchanged at 13950 / 900.