@derek-m cheers man, im probably missing something but i dont get what you mean by running continuously, the stats turn off the pump when at 21. hours later if it drops to20 it will start again so dont understand how i can keep rooms at constant temp.

Posted by: @newhouse87

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@derek-m cheers man, im probably missing something but i dont get what you mean by running continuously, the stats turn off the pump when at 21. hours later if it drops to20 it will start again so dont understand how i can keep rooms at constant temp.

To keep the rooms at a reasonably constant 21C, you would need to set all the thermostats to 22C, except for rooms like bedrooms that you may wish to have a lower temperature. Then lower the WC curve setting at the lower outside temperature end of the curve, until the rooms are at 21C, with the heat pump operating almost continuously.

Try the following WC curve settings and see how your system operates. Set the WC curve to 30C LWT at -5C outside temperature, and 25C LWT at 20C outside temperature. If the rooms do not reach 21C, then increase the -5C end to 31C. The system response will be slow, so allow quite a long period of time before making any further adjustments.

@derek-m ok thanks, ill attempt that for all living areas which is half the house essentially during the week. Dont fancy heatpump running longer then normal however as surely that is going to more costly then heating from 20-21 intermittently.

sun room calling for heat now, getting that pump revving and up and down sound again, happens intermittently, flow rate from sensor going from 19 back down to 10, first time i have checked flow rate in operation. any reason for this, that cant be right. Jumping massively every 2 seconds in conjunction with revving derevving, would it be airlock on a loop? 

Posted by: @newhouse87

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@derek-m ok thanks, ill attempt that for all living areas which is half the house essentially during the week. Dont fancy heatpump running longer then normal however as surely that is going to more costly then heating from 20-21 intermittently.

Do you remember the story about the Hare and the Tortoise? At the moment you would appear to be running your heat pump like the Hare, when it is more efficient to run it like the Tortoise in colder weather.

Posted by: @newhouse87

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sun room calling for heat now, getting that pump revving and up and down sound again, happens intermittently, flow rate from sensor going from 19 back down to 10, first time i have checked flow rate in operation. any reason for this, that cant be right.

It is probably occurring because your heat pump is only supplying one room, and this is causing the speed of the water pump to keep being varied. Try turning up more thermostats and see what happens to the flow rate.

@derek-m Jesus you're a hp whisperer. That worked flow steady at 32l/min now. Thought hp would adapt to number of loops open. some defrost/oilactive mode pooped up and then went off after adding loops. going opening all living areas now for good.

Edit, steady at14.7 now which means all loop flow rates have reduced below 2, dont think i have copped that before. anything to do with flow temp and rates will increase when delta t near 5 again, currently lwt35 and return at25. 10loops open with that flow rate not ideal im thinking.

my head hurts. Back up near 30 and flows fine, must have been to do with return temps being so low initially.

@derek-m, we might have to add Heat Pump Whisperer to your signature – I love that – that's quite an accolade.

Posted by: @newhouse87

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Dont fancy heatpump running longer then normal however as surely that is going to more costly then heating from 20-21 intermittently.

Normal for a heat-pump is running continuously.
That's what it's designed to do, and you'll achieve a COP of 3 or above.

Heating intermittently, on demand, is achieved with a different device:

You can buy a 3kW electric fan heater for as little as £100

It has a COP of 1.0

@transparent had one of them at warehouse job years ago. cop of 3.05 at moment i think, including dhw. I know im missing something, i know i have to find lowest lwp to get house to temp, but i dont get the continous running thing, When i reach temp of room stats cut it off or are ye suggesting i find lowest lwt that will give me 21deg in each room and have stats calling for 22 so pump is continually supplying just enough heat to maintain21. Pump quite loud so dont fancy it running all night.

Posted by: @editor

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@derek-m, we might have to add Heat Pump Whisperer to your signature – I love that – that's quite an accolade.

Yes, the comment was much appreciated, but wait until he gets the bill. 😋 

There's already a bill attached to my forum avatar 😉