Ground Source Heat Pumps

beardymarrow

lovesgshp wrote: »

OK the pumps seem to be clear of air, so that is eliminated.
Your problem, from how I see it at the moment is the heat curve is far too low for the radiators. The pump is only trying to supply 31.9C @ 0C outside. This is why it is probably operating so much, as the rads are losing the heat faster than the UFH.
Are the rooms with the UFH at a reasonable temperature? If so, shut down the UHF system and turn the curve up to 5. The pump should run to the new flow temp. May take a while to settle for running time, but the rads should increase temperature.

Yes, the room that has the UFH is at a nice warm temperature. I have shut the inlet and outlet valves and switched off the pump on the UFH, and set the curve to 5 now. Will keep you up dated.

If that fixes it, then I guess I need a mixing valve on the UFH?

beardymarrow

Picture of the UFH set-up.

The two pipes along the top of the picture are the common feed from the external pump fed by the GSHP (which is on the right of this picture).
First vertical pipe on the right is obviously the feed into the UFH pump and then the top UFH manifold.
Second is the return from the bottom UFH manifold.
Third is the Central heating feed to one of the 3 rad zones
Fourth is the return from that same zone.
The top horizontal pipes then go on to the other 2 rad zones.
I know zones is not quite the right term as that suggest that they are individually controlled. They aren't they just have the ability to be isolated separately.

lovesgshp

Thanks.
Your return temps should now be at about 43C @0C outside, if you can confirm.
My honest opinion, would be to put in a 200ltr buffer tank to operate at a higher temperature, with the mixing valve to cool the flow to the UHF. It is a normal system we use here with a combination set-up.
Keep me updated, as your UHF will probably take about 24 hrs to need re-opening.

beardymarrow

lovesgshp wrote: »

Thanks.
Your return temps should now be at about 43C @0C outside, if you can confirm.
My honest opinion, would be to put in a 200ltr buffer tank to operate at a higher temperature, with the mixing valve to cool the flow to the UHF. It is a normal system we use here with a combination set-up.
Keep me updated, as your UHF will probably take about 24 hrs to need re-opening.

Return is at 36 for 0. It's actually 35.1degC target with the room temp influence taken into account and the current external temp of 3degC.

It doesn't see to have made a huge difference to the temperature plummet :-( on one cycle, but I'll leave it and see what happens and report back with a graph.

lovesgshp

What is the room sensor influence and where is it located?

beardymarrow

lovesgshp wrote: »

What is the room sensor influence and where is it located?

Room temp is set at 17.8, influence 5. It's in the hallway, which is currently at 17.5, so it's adding 1.5deg to the rad return target.

lovesgshp

My apologies Beardy. I had a temperature fine tune in my simulator of +7C so therefore it was reading the 43C. Change to 6 for the moment, with no room sensor influence.

beardymarrow

lovesgshp wrote: »

My apologies Beardy. I had a temperature fine tune in my simulator of +7C so therefore it was reading the 43C. Change to 6 for the moment, with no room sensor influence.

No worries. I've changed the slope to 6 (I've left the room sensor as it is for now as it's only adding 1degC at the moment). GT1 target is 37.5.

What I might do tomorrow is leave it at the settings as I've got it now, but turn off each of the 3 rad zones one at a time to see if any particular one is having more influence on the temp drop than the others (or if it's just overall load). I'll also work out which rads are on which zone (it sort of obvious from where they leave the boiler room, but not completely).

Cheers

Beardy

Xander_Sim

Beardy,

Our houses are similar in size, mine is a two storey and was built 4 years ago so this should help us a lot. You will have a EPC for the house so provided you are C or better your heat pump should be a lot cheaper to run than you mentioned a while ago.
I think it's all about your settings and you should be on the right track now with lovesgshp's great advice.

My heatpump is set at curve 5 with thermostat influence at 3 and set to 19.8degrees. This works a dream for me and I have no doubt will do for you.

One thing to note is that you have just made significant changes to the settings so your pump will work like the clappers for a day or two until the temperatures in the UFH screed stabilises.

I have some learnings I gained from my system for your upcoming investigations; I would hope if you follow this through you should save some serious pennies..
But your system is much more complex than mine which is going to be difficult to figure out.
I have one central thermostat in the ground floor hallway, when I first switched on the house I kept the doors closed and adjusted the valves on the manifold loops individually until everything was stable and I was happy with the temperature in the rooms even though they are different (bathrooms, bedrooms etc).
There are huge benefits to this and keeps it all simple.
One other major item is that while I was doing this I kept the upstair manifold off, I then found that the heat transferred and very little heat is required upstairs and is shut for a large part of the year which greatly reduces the water circulating in the system and therefore reduces the work done by the pump.

Lovesgshp's comment on a buffer tank sounds like a bloody good idea if you still continue to struggle with the rads. Or an option woul be to explore these fan assisted rads which work better with a UFH flow temp.
But to be honest it should work as is.

Oh a final note, I would remove the lower overnight set point temperatures as this may also confuse things and asks the heatpump to do quite a bit more work each morning rather than ticking over during the night.

All the best!
Xander

lovesgshp

Thanks Xander Sim for the input. It is always good to hear what other users think and have changed on their setups.
Are you UFH/rads combination/fan coils?