Heat Pumps - post here.

So i found the setting for fixed temp, on mine it is based off the "fixed return temp". I set 30 for now, will see what happens, I think this might be too high, as to get a return of 30 it would need to be delivering flow temps at start of around 38 to 40.

Johndoe, I followed a process similar to what you describe when setting with weather comp. trying to set curve end point between 28 and 32 at a typical outside temp, then adjusting when that temp changed. i.e setting 30 degrees when its 12 degrees outside, if house holds same temp at zero then the curve i regarded as correct, if the temp the house was holding was too high i then moved the curve "down". I cant set the bottom of my curve.

My IVT uses the return temp to calculate the heating setpoint on the curve as well. I believe most other uses supply temperature and degree-minutes. I'd say your return is high at 30, here is my current figures at less than zero outside. Once my underfloor "radiator forward" temp meets the setpoint the compressor slows and maintains it in or around that.

Weather compensating. The heating setpoint moves up and down with the weather or if you change the room temperature on the heat pump.

I'm on night rate so I setback by 1 degree during the day. The setback offsets the whole curve so even 1 degree drops my setpoint by 2 degrees. Depending on the weather it could be more or less.

It can run 24 hrs, i havent disabled it. It depends on the weather.

Lowering it by 1 degree today won't turn it off as it is cold and not expected to get above 4 all day. It does lower the compressor speed though. It really depends on the weather. Lowering it by 2 probably would turn it off.

Weird...i had found that website 5 minutes before you posted! Will take a look.

I know my heat loss is 1.98w/m, basically need 14.1KW pump. Design temps i dont know (didnt live here when installed). But are they not all more or less 35?!

Buffer is at the end of the line ! Research tells me they can go either end. Personally intuition says it's illogical to have it at the end in a large house !?

do you have "components tab" on heatpunk? (as per their videos?) cant seem to see this tab to add UFH

I define at the end as the colder pipe out of it enters the heat pump! So yes a volumiser, typically used for pumps that might be oversized to prevent cycling! Mine is anything but oversized!

Yes and the buffer has an immersion on it too which should kick in if the pump is struggling down at minus 2 or 3 outside air temp.

One option I have considered is joining the two pipes into the buffer, to setup a buffer. On paper the pump is just about the right size for house, buffer tank could be pushing it over the edge. This still doesn't really explain high KW usage on mild days though, I think.

On the subject of buffer tanks

https://renewableheatinghub.co.uk/how-to-correctly-install-heat-pumps-so-that-they-work-properly-and-efficiently

IMO if you have to use an immersion something is wrong. once immersion kicks in you are getting a cop of 1:1 and makes having a heat pump pointless. I dont even know why they exist on heat pumps.

When I first got my heat pump the immertsion was coming on for my heating (not hot water) due to a setting. Basiucally it was panicking it wasnt heating fast enough so it kicks the immersion in, when in fact it just needed more time because underfloor pipes take longer to heat up.

Id investigate the conditions of when the immersion kicks in for you and adjust it. that should give you a massive increase in COP.

Slight tangent; I wonder how many KW per day are lost up an open chimney (no fire ever put on in it)