Ground Source Heat Pumps

lovesgshp

Patrol wrote: »

More a case of me mis-stating it

4.1.1 reduced from -2 to -1.5.
OK

This is how I understand a buffer tank would work.

Iincreased volume of water in the heating circuit, e.g. from 160l +ufh / rads to 160l + ufh / rads + buffer.
Think you are confusing the DHW outer tank, as this has no connection to the heating system.

This would provide more consistent flow temperatures as e.g. x% extra water would contain y% extra heat and take longer to drop from peak heat to reheat point.
The tank would help to stabilise temperatures between the rads and the UFH, so ensure the rads could run at higher temps.

It would also help the GSHP as the heat cycles would be less frequent and longer duration, reducing the cycle startup overhead.
Yes

My GSHP is in a corner with the cylinder next to it so a buffer tank would have to sit the other side of the cylinder. I have a pump about 50cm from the GSHP heating supply pipe which I think might need to be moved to after the buffer tank so it draws from that rather than the GSHP. Then feed the buffer tank back to where the pump output goes.
There should be no problem in this. You may need to get the original supplier/designer just to specify the connections

I can get a quote for this work, presumably there is a sensible size of buffer tank to complement the GSHP, etc.
- UFH : 560 metres.
- Rads : 3 600mm x 480mm twins. 1 120mm x 480mm twin which I expect is not sufficient for the 5m x 5m room my daughter now occupies. Wasn't a problem when it was used as a junk room.
I think 200ltrs for the buffer would be ok,

& I haven't mentioned the towel rails (sigh). 3 900mm x 480mm which I don't really want much more than lukewarm.
No problem with the above, if they are thermostatically controlled and with bypass valves.

On the positive side, the heat pump has only used another 2 hours ground loop and my electric meter had a 15kw day which is usually only seen in the heat of summer.
Great, just keep monitoring it. You are in Spring there, so it is more difficult to gauge usage.

Another question. Is there a recommended way to check each manifold flow / return temperature such as sticky thermometers so I can check that is set up correctly too.

Never been asked that one, but there should be a manifold temp gauge, and you may be able to get a sensor like with GT1 that you could fit on the return line.

ruben93watson

Well, thanks for sharing. I liked the timer control settings and hot water settings.

Patrol

My heating was on last night so I took a reading, not sure at what point in the cycle this was so apologies if in first few minutes. Hot water was showing as not required at that point.

GT1 29.2 / 27.4
GT2 7.1
GT3 50 / 52.7 (it seems to hold heat better at 50 than at 48)
GT5 18 / 23.6
GT6 60.2
GT8 34.7
GT9 28.2
GT10 9.2
GT11 5.8

How you define short-cycling, it was on for 30 minutes after I spotted it which doesn't seem too short to me. Still no additional heat used but the ground loop hours increased from 13966 at 7pm to 13971 at 8 am today.

The UFH diagram I have suggests each circuit should be fully shut then opened between 1 and 3.5 turns with most at 2-2.5 (fully on is about 4.5 turns). This red side manifold was cooler than the no adjustment blue side manifold at the time of readings. I believe I read earlier about a 70% flow so need to go back and check as these settings sound like more than a 30% reduction overall.

lovesgshp

Patrol wrote: »

My heating was on last night so I took a reading, not sure at what point in the cycle this was so apologies if in first few minutes. Hot water was showing as not required at that point.

GT1 29.2 / 27.4
GT2 7.1
GT3 50 / 52.7 (it seems to hold heat better at 50 than at 48)
GT5 18 / 23.6
GT6 60.2
GT8 34.7
GT9 28.2
GT10 9.2
GT11 5.8
Figures look pretty good and GT1 in the range of the heat curve, with the GT2 temp. Gt8/9 perfect, as are 10/11.
No problem if you are happy with GT3 setting.
Is GT5 still set at influence 5?


How you define short-cycling, it was on for 30 minutes after I spotted it which doesn't seem too short to me. Still no additional heat used but the ground loop hours increased from 13966 at 7pm to 13971 at 8 am today.
30 mins is fine, at the outside temp settings, which would be lower overnight. It means the pump is not hitting the 1 hr countdown to the electric boost activating.
With reference to the short cycling, then I have linked a very interesting article below that is well worth a read. It is only for radiator systems, but interesting all the same, as covers buffer tanks in systems and their effect.

The UFH diagram I have suggests each circuit should be fully shut then opened between 1 and 3.5 turns with most at 2-2.5 (fully on is about 4.5 turns). This red side manifold was cooler than the no adjustment blue side manifold at the time of readings. I believe I read earlier about a 70% flow so need to go back and check as these settings sound like more than a 30% reduction overall.

With the UHF diagram, it should have a value for each circuit covered, specified by the room size and heating requirement. e.g Bathrooms to be warmer.
The 70% relates to the minimum heating area that the pump is covering, therefore, if 180m2, you can reduce to that amount, by closing circuits that are not needed.

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/65695/7389-effects-cycling-heat-pump-performance.pdf

HTH

Patrol

I'd dropped GT3 back to 49, must stop fiddling. GT5 is set to 5.

I think I read the 2011 article a couple of days ago. This one has so many graphs I don't know what to make of it

Heat cycle tonight, not sure how much I missed at the start but picked up lots of figures and went over an hour without additional heat. Sample below, earliest I caught, a middle one and a final one.

10.10 28.2/24 8.7 49/47.2 18/23.6 53.9 31.3 24.7 10.1 6.5
10.30 28.6/27.2 8.1 49/47.2 18/23.6 59.8 34.1 27.8 8.8 5.5
11.05 28.9/28.6 7.6 49/47.1 18/23.6 62.4 35.6 29.4 8.3 5.1

The pump didn't cut out but I noticed my electricity use jumped by 300w or so (I have a gadget in easy sight now) so assume it jumped from 1.3-1.4kw to 1.7kw. When I checked the heat pump it was in DHW mode.

11.15 25/28.9 7.5 49/46.8 18/23.6 65.4 47.9 43.5 8.2 5.1
11.20 25/27.7 7.5 49/48.7 18/23.6 75.3 51.6 46.3 8.2 5.1
11.32 25/25.7 7.4 49/52.6 18/23.6 78.1 56.3 50.7 8.2 5.3
+ off at 11.35pm at 53C.

Hours: 13974 / 900. Approx 3 hours ground loop since 8am, pity this doesn't go down to tenths or minutes. I'm guessing it was about 45 minutes through the day and almost 2 hours on the one run above as I thought it started at about 9.50pm.

I've refrained from posting for a while to see if it starts another cycle. Heating cycle starts after a 15 minute gap so adding next couple of readings.

23.50 29.2/24.9 7.1 49/52 18/23.6 58.3 32 25.4 9.9 6.4
23.55 29.2/25.6 7.1 49/51.7 18/23.6 58.6 33.2 26.5 9.5 6.1
00.05 29.3/27/7 6.9 49/51 18/23.6 59.5 34.8 28.5 8.5 5.3

Is GT3 DHW temp meant to drop so quickly on a heating cycle - I can remember thinking this question 3-4 years ago so wonder if the 3 way valve has been sticky for a long time.

lovesgshp

Patrol wrote: »

I'd dropped GT3 back to 49, must stop fiddling. GT5 is set to 5.
No problem with altering a few things, just try for the economy

I think I read the 2011 article a couple of days ago. This one has so many graphs I don't know what to make of it
Yes, it is quite intensive in the analysis, but it gives a lot more detailed figures, which is helpful

Heat cycle tonight, not sure how much I missed at the start but picked up lots of figures and went over an hour without additional heat. Sample below, earliest I caught, a middle one and a final one.

10.10 28.2/24 8.7 49/47.2 18/23.6 53.9 31.3 24.7 10.1 6.5
10.30 28.6/27.2 8.1 49/47.2 18/23.6 59.8 34.1 27.8 8.8 5.5
11.05 28.9/28.6 7.6 49/47.1 18/23.6 62.4 35.6 29.4 8.3 5.1
Quite a lag to pull the temp up by 1.4C from 10.30 to 11.05. GT5 bothers me though, please try it at influence 10, for a day or so. All other readings look OK.

The pump didn't cut out but I noticed my electricity use jumped by 300w or so (I have a gadget in easy sight now) so assume it jumped from 1.3-1.4kw to 1.7kw. When I checked the heat pump it was in DHW mode.
That is quite normal, as it is going into the faster heating mode for the DHW.

11.15 25/28.9 7.5 49/46.8 18/23.6 65.4 47.9 43.5 8.2 5.1
11.20 25/27.7 7.5 49/48.7 18/23.6 75.3 51.6 46.3 8.2 5.1
11.32 25/25.7 7.4 49/52.6 18/23.6 78.1 56.3 50.7 8.2 5.3
+ off at 11.35pm at 53C.
Temperature drop on GT1 is quite rapid in under 20 mins @ 3C.


Hours: 13974 / 900. Approx 3 hours ground loop since 8am, pity this doesn't go down to tenths or minutes. I'm guessing it was about 45 minutes through the day and almost 2 hours on the one run above as I thought it started at about 9.50pm.
Unfortunately, the controller does only indicate full hours, so it could have got to 3hrs 59 mins, so only show the 3 hrs.

I've refrained from posting for a while to see if it starts another cycle. Heating cycle starts after a 15 minute gap so adding next couple of readings.

23.50 29.2/24.9 7.1 49/52 18/23.6 58.3 32 25.4 9.9 6.4
23.55 29.2/25.6 7.1 49/51.7 18/23.6 58.6 33.2 26.5 9.5 6.1
00.05 29.3/27/7 6.9 49/51 18/23.6 59.5 34.8 28.5 8.5 5.3

Is GT3 DHW temp meant to drop so quickly on a heating cycle - I can remember thinking this question 3-4 years ago so wonder if the 3 way valve has been sticky for a long time.

It could be the valve still seeping a little bit still. You may need to change it, unless you used hot water in between times.

lovesgshp

Patrol.
This a bit of "a shot in the dark" idea, as we have only had the recent data on the heating side of the operation.
With the temperature dropping 3C on the return to the pump so quickly, then it may be the radiators upstairs causing the problem.
Therefore, leave GT5 on the 5 setting, close all the upstairs rads, apart from your daughters bedroom and the towel rails.
It's a long shot, but the rads may be the cause as on the same circuit as the UFH, and obviously they cool faster.

Patrol

Room influence set back to 5.

Looks like 3 radiators had been fully opened while the fourth was on frost setting - put them all on frost as a) she's not home tonight and b) it's not that cold upstairs this time of year.

Earlier post should have said 1200mm radiator not 120, probably obvious that was a typo but clarifying anyway.

It's warmer tonight (11C compared to 7C for the last couple of nights so no heat cycle)

Towel rails still open - I was going to work out which was the flow side on a heat cycle as they look the same. Suppose I could close both sides.

Patrol

Some more questions if you are able to help.

Pasteurisation cycle.
The has activated. I spotted it at 57C and it is using additional heat only with the ground loop light flashing on and off. After about 15 minutes it has increased to 59.2C and another 10 minutes sees it at 60.4C then another 10 minutes to 61.5C. Is this right or have I got some other issue.
- DHW supply and return are hot to the touch at both GSHP and DHW unit connections.
- Does bleeding the cylinder remove air from both the 300l and 160l sections.
- Is it likely there is something other than water in the cylinder (I'm not on mains water so suppose it is possible my borehole has drawn something like silt up over time). Any way to check.

Heating supply & return.
In addition to the UFH & radiator pipes these two pipes have a connection to each other with a red stopcock valve. This looks to be almost fully open (1 rotation from fully anticlockwise) and I have no idea whether this is correct.

Stopcock is A on photo.
Red line is the pipe between heating supply and heating return, cool to the touch.
Yellow line hot water supply is hot to the touch despite no heating being on.
Blue section is cool to the touch, as is hot water return.

http://i208.photobucket.com/albums/bb237/Gate70/Pipes.jpg

& 3rd question. The additional heat seems to be taking a similar time to heat the water as the ground loop so can I infer from this that the ground loop and refrigerant are probably OK and any issue lies elsewhere.

lovesgshp

Patrol wrote: »

Some more questions if you are able to help.

Pasteurisation cycle.
The has activated. I spotted it at 57C and it is using additional heat only with the ground loop light flashing on and off. After about 15 minutes it has increased to 59.2C and another 10 minutes sees it at 60.4C then another 10 minutes to 61.5C. Is this right or have I got some other issue.
If the cut-off is in the region of 60C, then that is OK
- DHW supply and return are hot to the touch at both GSHP and DHW unit connections.
- Does bleeding the cylinder remove air from both the 300l and 160l sections.
No, only the 160ltr, as the central unit is via the taps etc.
- Is it likely there is something other than water in the cylinder (I'm not on mains water so suppose it is possible my borehole has drawn something like silt up over time). Any way to check.
There should be a filter in the borehole supply, to prevent anything like that happening. No easy way to check.

Heating supply & return.
In addition to the UFH & radiator pipes these two pipes have a connection to each other with a red stopcock valve. This looks to be almost fully open (1 rotation from fully anticlockwise) and I have no idea whether this is correct.
That one is completely alien to me, but I have asked one of our design engineers to have a look at the pics and your comments, so hope he is not too busy and will give me a answer.
Stopcock is A on photo.
Red line is the pipe between heating supply and heating return, cool to the touch.
Yellow line hot water supply is hot to the touch despite no heating being on.
Blue section is cool to the touch, as is hot water return.

http://i208.photobucket.com/albums/bb237/Gate70/Pipes.jpg

& 3rd question. The additional heat seems to be taking a similar time to heat the water as the ground loop so can I infer from this that the ground loop and refrigerant are probably OK and any issue lies elsewhere.
The temp readings for the ground loop and GT8/9 look perfectly alright and in range, so no problem at the moment.

My apologies for taking so long to answer, but have had a broadband/telephone outage for the last couple of days, due to a tree breaking the line