Ground Source Heat Pumps

lovesgshp

Hi Beardy.
With reference to the IVT@home and anywhere. The reason that our guy was not aware of it, was that it is one of those things that were only available in certain countries and not in Italy.
It is a similar situation to the Worcester Bosch heat pumps, which only seem to be marketed up to the 11Kw unit, even though they are made by IVT. Above 11Kw, you have to go to the IVT brand. ( In the UK )

Patrol

OK, all working properly then and my lack of understanding. I assumed the DHW would be shut to minimise heat loss.

I made sure B was to the left (heating) and A to the right (DHW) as per the ESBE. Used the original nuts and whatever the thin compression joints are called as they looked OK (and better than me trying to replace them).

DHW dropped from 52.4 at 10.37 to 50.1 at 11.15. 49.5 at 11.57. 49.3 at 12.43. So 3C in just over 2 hours, including me testing the A-B a couple of times and bleeding everything. Had re-pressured the heating side to 1 bar as well.

The auto air vents - I had already opened them a bit and closed them before seeing the comment. One was OK, the other had a few seconds of air - should this be a certain tightness and will I have messed this up by tightening it manually.

Patrol

Thanks guys, without your help I'd probably assume this was just the running cost of a heat pump - it would still have been cheaper than the alternative (oil).

& here it is before I tidied it up



49.3 @ 12.49
48.7 @ 15.15. 0.6C in 2h26m.

Currently set at 48, so think it should kick in at 45.9C.

Only 7.8 units since midnight so looks like another light day.
14030 hours ground loop and 903 hours additional heat.

Am I right in thinking the additional heat should only be used 57-65C so 10 minutes or so for the weekly pasteurisation cycle (at least in the summer and I'll need to review winter performance).

beardymarrow

Patrol wrote: »

Thanks guys, without your help I'd probably assume this was just the running cost of a heat pump - it would still have been cheaper than the alternative (oil).

& here it is before I tidied it up



49.3 @ 12.49
48.7 @ 15.15. 0.6C in 2h26m.

Currently set at 48, so think it should kick in at 45.9C.

Only 7.8 units since midnight so looks like another light day.
14030 hours ground loop and 903 hours additional heat.

Am I right in thinking the additional heat should only be used 57-65C so 10 minutes or so for the weekly pasteurisation cycle (at least in the summer and I'll need to review winter performance).

Good work mate. I bet your really satisfied to have done something like that yourself, instead of calling out "the guy".

On another note, I might have sorted by DHW loss. I have had the recirc pump switched off for ages, but the valves to it were still on (no problem I thought, water won't flow through a pump that's off, especially with nothing to push it). Well, I noticed that the pump and the pipes were warm the other day, so I closed the valve last night, and this, is the result.



I'd be well happy with 7.8 units in 15Hrs. I consider a good day to be under an average of 1kWH (so 24kWh for the day). I track it, and if the usage is lower than the hour I'm happy :-). Hopefully even better now.

beardymarrow

Patrol wrote: »

Hysteresis.
I'm probably wrong but I thought it worked like this. At a 51C setting a DHW cycle would heat to 55C to get the 4C hysteresis. It would then cool until 2C below the desired temperature, i.e.49C and the next cycle would start.

52C would give a range of 56C down to 50C. That's what your data shows.
49C would give a range of 53C down to 47C. That's what my data showed.
48C would give a range of 52C down to 46C. That's what I should now see, and what lovegshp may be seeing.

I observed a cutoff at 53.3C which then rose to 53.7C before the cooling started which ties in with what lovegshp said would happen with a double skinned cylinder.

(hope I've got that right)

Hi,
That's not how I thought it would work. I thought if you set it at 52c with a hysteresis of 4c, then it would go between 50 and 54c. That's how the GT1 works, anyway.

My readings are exactly like what you've put though. It goes between 50c and 56c. When I've played with different temps and hysts, it seems to drop to half the hyst below the target and then go up to half the hyst above the target plus 2c (like you say)

I guess lovesgshp is the man with the answer. If he's got a pdf describing it like he did for the pasteurisation cycle?

lovesgshp

beardymarrow wrote: »

Hi,
That's not how I thought it would work. I thought if you set it at 52c with a hysteresis of 4c, then it would go between 50 and 54c. That's how the GT1 works, anyway.

My readings are exactly like what you've put though. It goes between 50c and 56c. When I've played with different temps and hysts, it seems to drop to half the hyst below the target and then go up to half the hyst above the target plus 2c (like you say)

I guess lovesgshp is the man with the answer. If he's got a pdf describing it like he did for the pasteurisation cycle?

With the hot water hysteresis on the HT series pump, then GT3 decides the start temp, but GT9 the shut down. This is why you tend to get the higher reading in GT3, than the hysteresis.

Patrol

Sounds like you're making great progress Beardy, I'd be living without instant hot water on that evidence. & yes I'm glad I managed it myself. I couldn't see anything obvious with the ESBE but there is something like a nylon spacer each side - am tempted to hook it up to an outside tap and see how it performs under pressure.

& thanks for the continuing education lovegshp. I think you're saying that the hysteresis is taking the coldest part and making sure it is 4C above the setting to ensure no part of the circuit is a suitable home for bacteria

Next observation from me. Hope it is all OK but will mention in case not.

1) On a DHW cycle my GT1 (edited, originally said GT3) reading is still rising.
I've moved the sensor as far back as I can (40cm above the GSHP outlet and 35cm back; it then T's left toand right which I believe will be UFH and radiators). Moving it any further would only measure one side or the other, so stuck with location so far as I can tell.

After replacing the 3 way valve the GT3 still measures temperature increases, last one from 26.4 to 35.6. When I feel the pipes the heating return is hotter than the heating supply.

The heating return is vertical. The DHW return T's into this from a horizontal position inside the GSHP. I don't think the heating P1-G1 pump was on and it was cold so don't think that is drawing water round. Likewise my radiators, towel rails and manifold were all cold thanks to the LK Armature.

The Wilo pump at the bottom left of the GSHP is on a middle setting so I am assuming all is working OK and the 9C temperature rise measured on G3 is just a litre or two of water conducting heat as some warm water rises instead of being drawn down into the pump. Hence the reason why G3 should be located further away to prevent this sort of reading.

2) DHW expansion cylinder.
This mornings DHW cooldown lasted from 10.37am 53C to 5.50pm 47.9C then a bath was run. The next DHW cycle took about 32 minutes (I think the bath was topped up) and I observed temperature gain from 45.6C to 52.9C. I'd have thought that volume of cold water would have dropped temperature below 45C but couldn't see any evidence of that.

Anyway, the DHW expansion vessel has a 6 bar pressure valve. I noticed at the end of the heating cycle that about 4 drops a second were produced. I had to go out, coming back 2 hours later I saw it was still dripping about once every 7-10 seconds. Does that sound right - my borehole is set to just over 3 bar if that is relevant and that was based on the original advice re the GSHP.

Patrol

I set my DHW so it is off 10pm-5am weekdays 6am weekend last night. Also read back and saw Beardy has set his P2 pump to only work with the compressor which I could do. Why would the installer leave it on continuous if not necessary - I'm reading the manual now but haven't seen anything so far that says when you can and cannot have this set with the compressor.
Edit: In my head I think P1 is allowing the heating circuit to run through the bypass without it going through the GSHP, if P2 was also running the heating circuit would merge the two flows. When the compressor is on P2 engages and merges warmer water into the heating circuit. So no need for P2 to be on with a bypass, still not found an explanation in the manual but it might be there in technical terms that I haven't understood.
Edit2: It is mentioned on pay 65 that you can set to either if a bypass is present but doesn't say why you might want to.

beardymarrow

lovesgshp wrote: »

Try at level 2 for 24hrs. Hopefully it will not alarm. Check the in/out temps when you can.

Tried the ground loop at Speed 2 for a couple of days now, and no alarm.

Here are the temps from a recent DHW heat cycle

Time	GT10	GT11	GT3x
06:57	22.8	22.7	49.6
06:58	14.6	20.5	49.6
06:59	9.5	10.1	47.9
07:00	7.7	5.6	47.9
07:01	7.1	4.1	47.9
07:02	6.8	3.1	47.9
07:03	6.6	2.6	48.8
07:04	6.5	2.3	48.8
07:05	6.5	2.2	49.9
07:06	6.5	2.2	50.7
07:07	6.4	2.1	50.7
07:08	6.3	2	51.4
07:09	6.3	2	51.9
07:10	6.3	2	51.9
07:11	6.3	2	52.3
07:12	6.3	2	52.9
07:13	6.3	2	53.4
07:14	6.3	2	53.4
07:15	6.3	2	54
07:16	6.3	2	54.7
07:17	6.2	2	54.7
07:18	6.2	2	55.2
07:19	6.1	2	55.6
07:20	6.1	2	55.6
07:21	6	2	56.1

What do you think? Are these better? Not sure what I'm looking for to be honest :-)

beardymarrow

Patrol wrote: »

I set my DHW so it is off 10pm-5am weekdays 6am weekend last night. Also read back and saw Beardy has set his P2 pump to only work with the compressor which I could do. Why would the installer leave it on continuous if not necessary - I'm reading the manual now but haven't seen anything so far that says when you can and cannot have this set with the compressor.
Edit: In my head I think P1 is allowing the heating circuit to run through the bypass without it going through the GSHP, if P2 was also running the heating circuit would merge the two flows. When the compressor is on P2 engages and merges warmer water into the heating circuit. So no need for P2 to be on with a bypass, still not found an explanation in the manual but it might be there in technical terms that I haven't understood.
Edit2: It is mentioned on pay 65 that you can set to either if a bypass is present but doesn't say why you might want to.

lovesgshp wrote a while ago :

With the bypass scheme P1-G1 pump run continuously during the winter and P2-G2 run with compressor.

from his engineer which makes sense to me.

P1 draws water round the rads and back across the bypass with P2 off (make sure that your GT1 temp sensor is on the rad side of the bypass though. Mine wasn't, it was on the pipe just as it went into the HP).

With P2 on permanently, then it would be drawing water round the rads and then through the heat exchanger as well, which seems unnecessary to me.

I expect IVT defaults to P2 permanently on as that's what you'd have with no bypass and doesn't cause any harm with a bypass. If they did the opposite, then there'd be problems with people having no bypass but not changing that setting.