Ground Source Heat Pumps

beardymarrow

Patrol wrote: »

Have you still got the recirculating DHW pump on and did you try without it for a few days to identify it as the culprit or rule it out.

At the moment you're doing 15 minutes something like 12 times a day so 3 hours a day to heat your water. At 1.7kw ground loop that is 5kwh so a minimum of 50p and likely more depending on your tarrif.

lovesgshp, do you know how the cooling time compares to your own.

Mine is not a consistent figure, either in time to heat up or cool again.The pasteurisation cycle last night was very slow and I reduced the UFH flow and then the towel rail flow, which seems to have made a difference. Might monitor it for a little while before getting the 3 way valve replaced so I have a baseline to compare against.

I have had the recirc pump off for a few days, but it's not conclusive. If there is a difference it's fairly marginal. The trouble is that the recirc is on a timer from 6am-9am and from 4pm-9pm and that's when I have the DHW demand (which of course is why it's times for then :-) )

I've tried to get a whole cool and heat cycle with it on (but no DHW demand), but only managed once, and it didn't seem to have made an appreciable difference to a complete cool and heat cycle with it off.

The strange thing is even with the DHW recirc pump off, the pipes leading to it and the pump itself are warm, so I think I need to turn the valves off as well to be 100% sure I'm not getting thermo syphoning (not sure if water can flow through a switched off CH pump?).

Mine's 2.7kW for the compressor, 100Watts for the heat fluid pump and 180w for the ground loop pump, so 3kW total when it's producing DHW. Stats taken from my OWL, which has been calibrated against the electricity meter and is 95% accurate. Tarrif is 12p per kWh so it's about £1.10 a day for DHW (slightly less as I don't heat the DHW between 22:00 and 05:00).

As an experiment I might set the DHW recirc to be on 24x7 and log a day, and then switch it off (and the valves to it) for a day to compare.

Patrol

& a DHW cycle (not sure if there was an earlier one between the pasteurisation and this).

14.03 DHW cycle starts, ground loop
14.03 31.1 / 16.3 / 46.8 / 266 / 58.8 / 51.1 / 45.6 /12.5 / 9.5
14.09 31.1 / 16.3 / 48.3 / 26.6 / 66.9 / 51.6 / 45.7 / 11.5 / 8.7
14.11 31.1 / 16.3 / 49.5 / 26.6 /68.3 / 52.1 / 46.3 / 11.4 / 8.7
14.15 31.1 / 16.3 / 50.7 / 26.6 / 67.7 / 54.6 / 48.8 / 10.7 / 8.1
14.19 31.2 / 16.4 / 51.9 / 26.6 / 65.4 / 55.6 / 49.8 / 10.4 / 7.9
14.22 31.2 / 16.4 / 53.1 / 26.6 / 66.7 / 56.7 / 50.9 / 10.3 / 7.7
14.24 Cycle complete, 53.7C

Reduced flow around heating circuit has sped DHW cycle up.
(21 minutes compared to 27-40 of previous cycles.
GT1 return temperature has increased slightly.
Towel rails are noticably warmer even on a minimal flow. I could turn them down a bit more; beyond the range of my hearing lol.

To me this indicates the 3 way valve does have a fault but I can prevent many of the effects by reducing the heating circuit flow (7 UFH and 3 towel rails as 3UFH and 4 radiators are all thermostat controlled). I guess this is a bad idea over winter or inconsistent weather though.

Will add some cylinder temps over the next few hours if I remember.

beardymarrow

Patrol wrote: »

& a DHW cycle (not sure if there was an earlier one between the pasteurisation and this).

14.03 DHW cycle starts, ground loop
14.03 31.1 / 16.3 / 46.8 / 266 / 58.8 / 51.1 / 45.6 /12.5 / 9.5
14.09 31.1 / 16.3 / 48.3 / 26.6 / 66.9 / 51.6 / 45.7 / 11.5 / 8.7
14.11 31.1 / 16.3 / 49.5 / 26.6 /68.3 / 52.1 / 46.3 / 11.4 / 8.7
14.15 31.1 / 16.3 / 50.7 / 26.6 / 67.7 / 54.6 / 48.8 / 10.7 / 8.1
14.19 31.2 / 16.4 / 51.9 / 26.6 / 65.4 / 55.6 / 49.8 / 10.4 / 7.9
14.22 31.2 / 16.4 / 53.1 / 26.6 / 66.7 / 56.7 / 50.9 / 10.3 / 7.7
14.24 Cycle complete, 53.7C

Reduced flow around heating circuit has sped DHW cycle up.
(21 minutes compared to 27-40 of previous cycles.
GT1 return temperature has increased slightly.
Towel rails are noticably warmer even on a minimal flow. I could turn them down a bit more; beyond the range of my hearing lol.

To me this indicates the 3 way valve does have a fault but I can prevent many of the effects by reducing the heating circuit flow (7 UFH and 3 towel rails as 3UFH and 4 radiators are all thermostat controlled). I guess this is a bad idea over winter or inconsistent weather though.

Will add some cylinder temps over the next few hours if I remember.

Yeah, should be no reason for GT1 to increase during DHW. It might spike at the end when the 3-way switches back to rad, whilst there is still a lot of heat in the circuit, but it shouldn't increase during (unless the 3-way is knackered of course).

The heating time doesn't look too bad. A bit worse than I get, but no crazily so.

Here's a recent one from me :-

Time	GT1	GT2	GT5	GT6	GT8	GT9	GT10	GT11	GT3x	Compressor
13:20	22.2	19.5	19.3	42.2	48.4	44.3	17.2	15.4	50.0	OFF
13:21	22.2	19.5	19.3	46.2	48.4	44.3	15.8	15.4	50.0	ON
13:22	22.2	19.6	19.3	58.1	50.0	44.9	8.4	9.7	49.9	ON
13:23	22.2	19.6	19.3	64.1	52.0	46.7	5.2	3.6	49.9	ON
13:24	22.2	19.6	19.3	69.2	53.0	47.8	3.9	1.6	49.9	ON
13:25	22.2	19.6	19.3	74.0	53.6	48.2	3.4	0.7	49.9	ON
13:26	22.2	19.6	19.3	80.7	53.9	48.5	3.0	0.4	51.1	ON
13:27	22.2	19.7	19.3	83.7	54.1	48.7	2.9	0.2	51.1	ON
13:28	22.2	19.7	19.3	85.4	54.4	48.8	2.9	0.2	52.0	ON
13:29	22.2	19.7	19.3	86.9	54.4	49.0	2.9	0.2	52.7	ON
13:30	22.2	19.7	19.3	88.5	54.7	49.4	2.8	0.1	52.7	ON
13:31	22.2	19.7	19.3	90.9	55.2	49.9	2.8	0.1	53.0	ON
13:32	22.2	20.0	19.3	92.3	55.8	50.6	2.8	0.1	53.3	ON
13:33	22.2	20.0	19.3	93.6	56.4	51.1	2.8	0.1	53.3	ON
13:34	22.2	20.0	19.3	94.5	56.9	51.7	2.8	0.1	53.7	ON
13:35	22.2	20.0	19.3	95.5	57.3	52.1	2.8	0.1	54.1	OFF

All taken from my lovely H10 :-)

Patrol

I'm starting to think I might be able to do the 3 way valve myself.

The supply heating pipe has the stopcock on the bypass and another stopcock with no wheel just before the (P1-G1) pump, which incidentally is the noisiest part of my entire installation with a constant hum. So I'm pretty sure that side can be done without draining.

There is no stopcock on the supply DHW but this is a up across and down to the DHW cylinder which is at the same height. Not sure whether that means I could disconnect it and only get a bit of water or if that is a terrible idea because of a siphon effect

I can think of a couple of people I can ask so will do that before doing anything rash. Also I measured the circumference of the pipes, 75mm so that makes the diameter 24mm so not 22 or 28. Or is 22 the internal measure?

(I don't know much about plumbing or electrics, happy to learn but not if I'm intending doing something dangerous).

lovesgshp

Times do not look too bad for the reheat of the DHW considering you both have large tanks. The heat loss, I have never really looked at on mine or any other, but I have the integrated cylinder in the C11.
Beardy: Your figures look pretty much OK, but the GT10/11 temp drop is quite high, especially as the weather is getting warmer.
Patrol: The temp increase in GT1 at the end of the DHW cycle, still seems to point to the 3 way causing the problem. May be good to get a quote from the installer to replace, plus the other earlier suggestions, as in post 442.

lovesgshp

22 mm is the outside dimension. 28mm is used for the ground loops, or in the E14 and higher rate pumps for the heat supply.

beardymarrow

Patrol wrote: »

I'm starting to think I might be able to do the 3 way valve myself.

The supply heating pipe has the stopcock on the bypass and another stopcock with no wheel just before the (P1-G1) pump, which incidentally is the noisiest part of my entire installation with a constant hum. So I'm pretty sure that side can be done without draining.

There is no stopcock on the supply DHW but this is a up across and down to the DHW cylinder which is at the same height. Not sure whether that means I could disconnect it and only get a bit of water or if that is a terrible idea because of a siphon effect

I can think of a couple of people I can ask so will do that before doing anything rash. Also I measured the circumference of the pipes, 75mm so that makes the diameter 24mm so not 22 or 28. Or is 22 the internal measure?

(I don't know much about plumbing or electrics, happy to learn but not if I'm intending doing something dangerous).

You'll be fine with the syphon effect on the DHW pipe. Just don't suck on the pipe after taking the 3-way valve off :-) You'll just get the water that's in the horizontal bit of pipe. Stick a bucket under the 3-way valve when you remove it. There's bags of room.

The pipes should be 22mm (external diameter) unless you've got an E14 or E17.

beardymarrow

lovesgshp wrote: »

22 mm is the outside dimension. 28mm is used for the ground loops, or in the E14 and higher rate pumps for the heat supply.

Damn you! :-) I was determined to help, but you beat me to it.

beardymarrow

lovesgshp wrote: »

Times do not look too bad for the reheat of the DHW considering you both have large tanks. The heat loss, I have never really looked at on mine or any other, but I have the integrated cylinder in the C11.
Beardy: Your figures look pretty much OK, but the GT10/11 temp drop is quite high, especially as the weather is getting warmer.
Patrol: The temp increase in GT1 at the end of the DHW cycle, still seems to point to the 3 way causing the problem. May be good to get a quote from the installer to replace, plus the other earlier suggestions, as in post 442.

Thanks. What would the GT10/11 drop suggest is the problem?

I'm OK with the heat up times. It's the time to cool down that is still bothering me.

Those figures were from the 30th April.

Here's a more recent example from earlier today.

Time	GT1	GT2	GT5	GT6	GT8	GT9	GT10	GT11	GT3x	Compressor
13:57	22.0	14.7	19.4	39.5	42.4	22.0	15.1	12.5	52.0	OFF
13:58	22.0	14.7	19.4	39.6	42.4	22.9	15.1	12.5	52.0	ON
13:59	22.0	14.7	19.4	55.5	42.0	41.6	13.5	9.0	51.7	ON
14:00	22.0	14.7	19.4	66.3	49.1	48.4	6.2	4.4	51.3	ON
14:01	21.9	14.7	19.4	73.6	54.4	48.4	5.5	2.8	51.3	ON
14:02	21.9	14.7	19.4	82.7	55.6	49.9	5.2	2.3	51.3	ON
14:03	21.9	14.7	19.4	85.8	55.6	49.9	4.9	2.1	52.9	ON
14:04	21.9	14.7	19.4	87.3	55.8	49.9	4.8	1.9	52.9	ON
14:05	21.9	14.7	19.4	88.8	55.9	50.0	4.8	1.9	54.1	ON
14:06	21.9	14.7	19.4	90.0	56.1	50.0	4.7	1.9	54.6	ON
14:07	21.9	14.7	19.4	90.9	56.3	50.1	4.6	1.7	54.6	ON
14:08	21.9	14.7	19.4	93.2	56.9	50.7	4.6	1.7	54.9	ON
14:09	21.9	14.7	19.4	94.5	57.8	51.7	4.6	1.7	55.0	ON
14:10	21.9	14.7	19.4	95.5	58.6	52.7	4.6	1.7	55.3	ON
14:11	21.9	14.7	19.4	96.5	58.8	53.1	4.6	1.7	55.3	OFF

Patrol

Beardy, what is your GT1 return value doing during the cooldown. I was wondering if your 3 way valve was better but not 100%.

I've made a note of my latest cooldown figures.
DHW cycle: Increases, e.g. from 28C to 32-35C.
Cooldown: Decreases to 28C in 30-60 minutes. Then stabilises.

DHW seems to drop very quickly from 53C to 51C (about 40 minutes) then slower from 51C to 49C (2 1/2 hours). Maybe my valve is closing over time, say with crud being deposited each DHW cycle and slowly clearing as the liquid circulates and flushes it out before doing exactly the same next cycle.

I suppose I could test that by switching off after a DHW cycle (GSHP, the pump on the supply heating pipe and the pump on the UFH manifold) and removing the 3 way valve for inspection.