Ground Source Heat Pumps

beardymarrow

Cardew wrote: »

As I have said on more than one occasion, the posts above demonstrate one of the biggest flaws of heat pumps; namely the degree of technical expertise required of the end user to enable the system to operate properly - or even detect a fault.


How do manufacturers/installers expect people used to gas/oil CH to cope? My wife 'ain't thick'(as her MA might demonstrate) but she would have neither the knowledge or inclination to operate such a system.

Hi Cardew,
I sort of agree. Yes, they are more complex, but they need to be to be efficient.

In my limited experience and knowledge, it's not the fact that its a GSHP that means it's complex, it's the weather compensation, and a gas/oil boiler with weather compensation would be just as complex.

If I had oil or gas I also wouldn't know there was a problem, as I'd have no data to go on. A standard thermostat only boiler would be less efficient and less comfortable/stable as all they are doing is reacting to the internal temp (unless they are more complex and have weather compensation, in which case you're back to the GSHP complexity, as I say).

In my particular case I think I've actually not got a GSHP problem at all, it's more a plumbing one and an oil/gas boiler would have the same issue (mix of rads and UFH with no differentiation between the two).

This is my first winter in the house with a GSHP, so this is all set-up work for me. Hopefully (fingers crossed), once it's all set-up, it's leave it and forget about it.

However, having said all that, without lovesgshp, Patrol and others, I'd be royally screwed as I'd have to wait a couple of weeks to get an expert out (due to lack of experience of the systems by plumbers). So, the real problem (for me) is lack of experienced knowledgeable plumbers in GSHP.

lovesgshp

Hi Beardy.
Have a look at P55 of the manual, this gives you all the info required, re connections etc.
Buffer tank, I would say 200 ltr.

beardymarrow

lovesgshp wrote: »

Hi Beardy.
Have a look at P55 of the manual, this gives you all the info required, re connections etc.
Buffer tank, I would say 200 ltr.

Thanks mate, buffer tank may be a no go due to physical space left (the GSHP and my 300l DHW tank take up pretty much all the space in my boiler room ). I'll measure tonight, but I can't see how it would fit in.

No reason why I can't do the mixer valve though, at least that will enable me to send curve 4 to the UFH and Curve 6 or 7 to the Rads. I don't suppose you have a certain make of valve that you normally use for that do you? I'm guessing it's the same type of valve as the 3-way that split the DHW and CH water? and then I need the GT4 from IVT and the cable to connect the valve to the GSHP. All seems easy enough.

lovesgshp

You will need to talk to ICE re the valve, as we have different makes here and they would be best to advise on that. They should also be able to supply the GT4 connection cable, etc. for you.
I honestly do not know why this was not specified in the initial planning. If you can fit the buffer tank in as well you will be much better off and cut down operating times.

beardymarrow

lovesgshp wrote: »

You will need to talk to ICE re the valve, as we have different makes here and they would be best to advise on that. They should also be able to supply the GT4 connection cable, etc. for you.
I honestly do not know why this was not specified in the initial planning. If you can fit the buffer tank in as well you will be much better off and cut down operating times.

Cool. Will do. I agree, from all I've read (including the instruction manual where both the mixing valve and buffer tanlk are explicitly recommended by IVT).

Whilst I'm on I did read this last night which was really interesting - https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/198850/hot_water_cylinders_buffer_tanks_heat_pumps.pdf

lovesgshp

beardymarrow wrote: »

Cool. Will do. I agree, from all I've read (including the instruction manual where both the mixing valve and buffer tanlk are explicitly recommended by IVT).

Whilst I'm on I did read this last night which was really interesting - https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/198850/hot_water_cylinders_buffer_tanks_heat_pumps.pdf

Thanks for that link Beardy, which I have read through and now my brain hurts, as it was so confusing.:think:
It went from condensing boilers to heat pumps, DHW tanks which it did not specify whether double skinned or not. With the buffer tanks they only seemed to concentrate on rad type supply and seeing how the rads were stacked above each other in one picture, the test would be very difficult to support in a normal household enviroment. Also, they were not even using a heat pump, just a electric heater to simulate.
Just poured a glass of wine to get over it:beer:

Patrol

So if I understand correctly a GSHP, UFH & radiators with no mixer valve or buffer tank is not ideal;
- The heating circuit will run at circa 35c, ideal for UFH but not optimal for radiators even if oversized (Long response time, costs and potentially never reaches desired temperature).
- The GSHP will cycle more than necessary as the small quantity of water in the heating circuit cools rapidly as it does it's job of transferring heat to the property (Increased wear & running costs).

Adding a buffer tank and mixer valve allows a store of water at a higher temperature (in the 40's?). Benefits;
- Radiators run closer to their optimal temperature efficiency.
- GSHP has a longer heating cycle but more than offset by reduced recycle time. Slightly reduced COP?
- UFH unaffected. Small amounts of this higher temperature water are mixed in on a more frequent basis than GSHP recycle times to maintain close to 35c.

Is that about right?

lovesgshp

Yes , Patrol, you are right and a excellent explanation of the situation.

Silent_Dancer

beardymarrow wrote: »

Hi Cardew,
I sort of agree. Yes, they are more complex, but they need to be to be efficient.

In my limited experience and knowledge, it's not the fact that its a GSHP that means it's complex, it's the weather compensation, and a gas/oil boiler with weather compensation would be just as complex.

If I had oil or gas I also wouldn't know there was a problem, as I'd have no data to go on. A standard thermostat only boiler would be less efficient and less comfortable/stable as all they are doing is reacting to the internal temp (unless they are more complex and have weather compensation, in which case you're back to the GSHP complexity, as I say).

In my particular case I think I've actually not got a GSHP problem at all, it's more a plumbing one and an oil/gas boiler would have the same issue (mix of rads and UFH with no differentiation between the two).

This is my first winter in the house with a GSHP, so this is all set-up work for me. Hopefully (fingers crossed), once it's all set-up, it's leave it and forget about it.

However, having said all that, without lovesgshp, Patrol and others, I'd be royally screwed as I'd have to wait a couple of weeks to get an expert out (due to lack of experience of the systems by plumbers). So, the real problem (for me) is lack of experienced knowledgeable plumbers in GSHP.

I have weather comp on a gas boiler. Apart from adjusting the bottom end of the heat curve up to -3°C to suit UK heating design parameters. I have had to do nothing to it.

The issue is not weather compensation it is to do with the fundamentals of running a low temperature heating system. With low flow temperatures you can not respond quickly to changes in demand either due to the weather or from the occupants. The theory behind heat pumps is fine but the reality is different.

lovesgshp

Silent Dancer.
You are operating a gas system, as against a GSHP.
You can in no way compare the 2, as your system is completely different.
The thread is GSHP, not gas.