Ground Source Heat Pumps

lovesgshp

OK, some answers back from our design engineers. Please excuse the English if it does not sound right. Will try to correct in the text..
In relation to the photo and your information:
"It seem a standard IVT scheme with bypass (see P55 of the manual). The "red stopcock valve" is not needed.
The system works fine if the flow on the radiator (P1-G1 pump) is greater than or equal to the nominal flow on the heat pump (P2-G2 pump). We usually choose this bypass scheme (instead of direct scheme) when the pump P2 can not guarantee the nominal HP flow on the radiator due to high pressure drop on pipes/radiator. Accumulator tank is not usually needed.
If accumulator is needed, we usually choose the xxxx scheme.(xxxx relates to a system local to me )

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

In my opinion blu is not the radiator return, but radiator flow (hot, supply), please check the arrow on the pump.
Maybe the yellow pipe is hot because it is heated by proximity to the domestic hot water pipe...... or maybe there is a three-way valve problem? ... but in this case you have to find also the radiator hot, not only the first meter of the pipeline.

Write me if something is not clear and please keep me informed if I'm right or wrong."

As I had only sent him your comments with the pics, I then asked about the UHF/Rad system.
"UFH definetly cannot work at radiator temperatures.

Maybe there is also a room thermostat that stops the UFH when the temperature at the ground floor is reached?
This solution may be acceptable with a manual mixing valve set to 35°C for the UFH and 100l buffer tank connected to radiator system.

Unless buffer tank I can suggest:
room sensor GT5 on first floor, radiator settings and mixing valve for the UFH
HP settings:
1.1= 4,5-5
1.2= +5,0
1.10= 20°C
1.11= 8
Install mixing valve for the UFH on ground floor. It is possible to try with manual mixing valve (range 20-50°C) set to about 30-35°C and manually adjusted if/when needed, according to the ground floor temperature."

Hope you understand what he is saying in the 2nd answer.

Patrol

Thanks, much appreciated.

I'd been looking at the manual and pages 54-55 mention a bypass if the heating circuit flow can't be guaranteed. That's the only thing I can think that red valve might be for. 3 of the 10 UFH loops are thermostat controlled as are the radiators.

I hadn't realised DHW and heating functions used different amounts of electricity but from your explanation and then re-reading the final page of the manual think I see how it works. 1.4kw for heating at 35C, 1.7kw for DHW at circa 50C.

With that breakdown and additional heat at 6kw I believe the GSHP has used 26,300kwh of mains electricity since installation (29 Nov 2007) so about 4000kwh a year.

Patrol

Just seen your 2nd reply.

Blue/Yellow is heating supply. Only the first 60cm or so heats up, radiators and UFH manifolds don't heat up. The proximity heating sounds logical.

I'm regretting not having been around when the plumber installed it but I had work commitments around the country and I then made the mistake of not asking about it because I was focusing on what was left to do rather than what had been done.

UFH/radiator temperatures. The system appears to be set for UFH, i.e. the radiators run cool. The heating supply pipe goes into a pump and then into a T so I assume one side of that is UFH and the other radiators. There is no thermostat upstairs, it relies on the radiator stats and if the upstairs rooms are shut they will be colder than the rest of the house in winter, i.e. underheated.

I think I understand the second answer, I need to move the sensor, add a mixing valve and a buffer tank. Or live with a cold upstairs.

What I'm not sure about from the answer is what to do about the red valve. I think the suggestion is that I should close it, either entirely or a lot further than it currently is (about 1 turn out of 4). Edit; re-reading I think the suggestion is to have it fully open.

& pasteurisation continues to 65C - I went to bed.

lovesgshp

Patrol wrote: »

Just seen your 2nd reply.

Blue/Yellow is heating supply. Only the first 60cm or so heats up, radiators and UFH manifolds don't heat up. The proximity heating sounds logical.

I'm regretting not having been around when the plumber installed it but I had work commitments around the country and I then made the mistake of not asking about it because I was focusing on what was left to do rather than what had been done.

UFH/radiator temperatures. The system appears to be set for UFH, i.e. the radiators run cool. The heating supply pipe goes into a pump and then into a T so I assume one side of that is UFH and the other radiators. There is no thermostat upstairs, it relies on the radiator stats and if the upstairs rooms are shut they will be colder than the rest of the house in winter, i.e. underheated.
Yes, the temperature settings are for a UHF system.

I think I understand the second answer, I need to move the sensor, add a mixing valve and a buffer tank. Or live with a cold upstairs.

What I'm not sure about from the answer is what to do about the red valve. I think the suggestion is that I should close it, either entirely or a lot further than it currently is (about 1 turn out of 4).

You have the 2 options with the 2nd answer, either with the mixing valve and the buffer tank, or without the buffer and reset to the figures shown, plus the mixing valve and sensor move.
The comment on the red valve, is just that it is not needed, so just leave open.

Will check tomorrow about the peak DHW as 65 is high.

Patrol

Cheers.

Don't think 65C is configurable, at least not that I can see. Software version is 3.06.

beardymarrow

lovesgshp wrote: »

Good to hear that everything is running smoothly.
Have not used the H10, but looked at their video, unfortunately in Swedish and it appears to be a very good information unit. Very detailed and at least you can change settings from the PC as well. Keep me updated, plus a few more users would probably like to hear of the "tweaks" that you have managed with it once installed.

I've had the H10 connected for a couple of weeks now, and I've got to say, it's a brilliant bit of kit.

I've managed to tweak my curve lower without sacrificing any comfort, as I've spotted that the CH was kicking in to bump the rad return up by a degree or two fairly frequently, when actually the room temp was fine. Also been able to better fine tune the DHW Off times.

Also, spotted that my P2 pump is permanently on, so I have changed that on the HP to only switch on when the compressor is on (I have a bypass pipe, so no need for this to be on constantly). It's only a small amount of electricity saved, but it all helps.

Since these tweaks I've managed a sub 24kWh day for the first time, and that was on a day when the outside temps were comparable to previous 30kWH days.

For anyone that likes to have all the data available to them, I'd say the H10 is essential!

If anybody needs any help with an H10, give me a shout, and I'll be glad to help.

Cheers

Beardy

beardymarrow

Patrol wrote: »

Cheers.

Don't think 65C is configurable, at least not that I can see. Software version is 3.06.

I think you're right. The manual for my system says that it just adds 5c to the DHW temperature. It doesn't say if that's to the GT3 target or to the GT3 off value though, so if set to 50c, not sure if that means 55, or actually 58c. Of course temp is measured fairly low down the cylinder anyway, so max temp will be higher, and min will be lower in any case.

I have just noticed something though, while going back through my H10 stats. The DHW never gets above 54c (it's set at 51c), so that's just the normal 50-54c hysteresis.

I wonder if this is because the hot water peak is set to come on overnight, and I have my DHW set to not be on overnight (menu 4.3), so when it is supposed to pasteurise it's actually switched off, and instead of doing it next time it's on it just doesn't do it at all?

Having said all that, this info - http://www.accepta.com/environmental-water-wastewater-knowledge/legionella-legionnaires-disease-knowledge/281-legionnaires-disease-domestic-hot-water-systems says "This latest research, combined with earlier studies, now suggests the responsible bacteria often grow in the biological slime lining residential hot water pipes and domestic central heating systems", so unless the hot water is run whilst the tank is at the high temperature, it's not going to kill the bacteria anyway.

lovesgshp

With reference to the 65C and the manual. I was caught out on this as well, as the manual is actually incorrect. The cut-off is 65C and have had that confirmed today.
With regard to the time it activates, then will have to check, as in many cases the DHW is turned off overnight.
I must say that I have never monitored it and my activation is every 30 days.
Beardy. Glad the H10 unit is working well and you are able to make more adjustments.
Am emailing you both a PDF of the actual operation of the Peak setting.
HTH

Patrol

Thanks.

The diagram more or less works as I expect, I didn't realise the unit switched from ground loop to additional at a specific temperature though so it is helpful to see a diagram and will have a look to see if the other values are configurable.

I feel safer leaving my interval at 7 days. Have read a fair bit about legionella over the last week and given the amount of iron and suspended material in my water don't want to compromise. My filters don't seem to pick up much, the last check being the only one where more than 5% of the gauze was blocked but both materials seem fine enough to pass through them

(if I wash a car the suspended material is left as a fine residue. At one stage we had slightly brown/orange cold water and noticably more discoloured hot water to the point where you couldn't see through bathwater. The borehole service company figured out the filter media was OK and the compressor needed replacing but only when their 3rd person came out to look so it had gone on for quite some time. Hence my thought about whether I could check the cylinder. Our water runs clear now so I'd guess it has either settled or flushed through, hadn't really considered if it had a longer term impact before as it was 2-3 years back)

Beardy, how does the H10 work. It looks like it needs a serial port or an additional USB adaptor and you periodically upload data to their website where it can be viewed and I guess expanded into more detail but that might be on a subscription basis.

beardymarrow

lovesgshp wrote: »

With reference to the 65C and the manual. I was caught out on this as well, as the manual is actually incorrect. The cut-off is 65C and have had that confirmed today.
With regard to the time it activates, then will have to check, as in many cases the DHW is turned off overnight.
I must say that I have never monitored it and my activation is every 30 days.
Beardy. Glad the H10 unit is working well and you are able to make more adjustments.
Am emailing you both a PDF of the actual operation of the Peak setting.
HTH

Thanks, yes that helps a lot. I'll let you know what the stats say after Sundays peak setting run. If the diagram holds true for my Rego 637W, then I expect the DHW to kick in at 07:00, and then run until it hits 65. I guess the add heat only kicks in if required, and it doesn't use the add heat if it can hit that temp from the HP only? I'll let you know though.