NEW Air Source Heat Pump - house is cold :(

[simondyntDBeK]

I live in an old property. I've had internal wall and loft insulation installed. I've had a new ASHP installed last week and my biggest fear seems to be coming true. The house is just really cold. The radiators are warm at the bottom but mostly cold. The temperature in the house won't get above 17.8 degrees and the ASHP is running constantly to achieve that. It's about 8-10 degrees outside currently.

Any tips? (other than putting the old oil boiler back!)

 

[monkeysballs]

Get the installer back it's their job to get it right

 

[simondyntDBeK]

Get the installer back it's their job to get it right

Yep they were really good to be fair. I'll give it a few more days then have a chat with them.

 

[monkeysballs]

Were heat loss calcs done for the property? We're rads changed?

What temp are you asking for? Any idea what the flow temp is?

 

[simondyntDBeK]

Were heat loss calcs done for the property? We're rads changed?

What temp are you asking for? Any idea what the flow temp is?

Yes they did a thorough survey. All new rads too. Temp is currently 17 and it’s so cold. I’ll be happy with early 20’s! Flow temp is 36.

 

[Johntheo5]

What is the rating of the ASHP? and what is the current flow/return temperatures?.

 

[fixitflav]

Yes they did a thorough survey. All new rads too. Temp is currently 17 and it’s so cold. I’ll be happy with early 20’s! Flow temp is 36.

Something's gone wrong. Heat pumps give lower water temperature than boilers, so need rads with your required output at that temperature (more area/different design).

 

[Johntheo5]

At a flowtemp of 36C and assuming retur of 30C then then the rad(s) output is only 23% of a 50deg rad at a room temp of 17C and only 17% with room temp of 20C, so should be oversized theoreticall y by a factor of 4.3!!, a factor of 2 to 2.5 is generally used.

 

[simondyntDBeK]

At a flowtemp of 36C and assuming retur of 30C then then the rad(s) output is only 23% of a 50deg rad at a room temp of 17C and only 17% with room temp of 20C, so should be oversized theoreticall y by a factor of 4.3!!, a factor of 2 to 2.5 is generally used.

Is this good or bad?!

 

[Rodders53]

Don't wait. Call em back in. If the system / design can't manage with the current outside temps what hope do you have on a -10C outside day.

You have checked for air in the radiators making them cold at the top compared to the bottom? To be frank though 36 C doesn't feel all that warm anyway (human blood temperature is around that figure).

ASHPs need a knowledgeable user and a degree of fettling. Read up all you can about how to use the one you have most effectively.

Make and model of HP, and info on the controls (weather compensation, zones thermostats, night setbacks, hot water cylinder etc.,.) will all be needed for them wot know more than I {I just glean stuff off this and MSE forums about HPs for my own possible future use} to advise on adjustments... But that's not a thing to any new user should need to do on a brand new install.

I think your flow temperature is possibly a bit too low for a radiator ASHP system and needs increasing a little; but will defer to those who install the systems for a living.

At least this cooler weather means you've found there's an issue now and not in November/December!

 

[monkeysballs]

I'm running less than 36c on my boiler yet heating to 20 ish

 

[gas112]

rads warm at the bottom . will ask the obvious Have you bled them

 

[simondyntDBeK]

rads warm at the bottom . will ask the obvious Have you bled them

Yep.

 

[fixitflav]

I'm running less than 36c on my boiler yet heating to 20 ish

I assume you have plenty of rad area relative to the boiler output, and anyway the weather's probably not too cold at the moment (depending on where you live)

 

[monkeysballs]

I assume you have plenty of rad area relative to the boiler output, and anyway the weather's probably not too cold at the moment (depending on where you live)

Indeed I'm correctly sized I was running 36 at like -2 today highs of 30 lows of 25 rads aren't silly sized though