Air Source Heat Pump Freezing

AuntyPolly

Flow temp was down to 30.5, it is currently 36.8 as outside temp slightly warmer. Are these reasonable. Like I said previously this results in the low room temperatures.

Reed_Richards

In December my heat pump developed a refrigerant leak.  The symptom was that the flow temperature kept dropping, even though it was quite mild out outside then.  

curlylegend

Thank you all so much for your helpful replies and comments. 
Despite getting quotes from seemingly respectable outfits it looks, as I suspected, we've been sold something that doesn't work very well.
The big problem I see in this area is that there are no genuinely knowledgeable installers. Engie, a big national organisation came in to see if they could do something, took one look and confessed that they knew nothing about that make and couldn't help. Apart from ripping it out and installing theirs. 
I wasn't exactly filled with confidence so declined the offer. And the original suppliers are just fobbing us off. Who do you complain to ?  Don't forget, we're in France where they invented and have perfected Bureaucracy ! 
For a couple of months we were compelled to use portable electrical fan heaters. If you could stand the noise they certainly got the room warm enough but cooled down rapidly as soon as they were turned off. And they gobbled electricity !  
We did at one point consider removing all the radiators and replacing them with ceramic cored electrical ones and just having the house centrally heated by electricity. All the estimates we were getting were telling us that it would be much more expensive to install and run than having a heat pump fitted.
So we'll soldier on, it won't kill us. We might even see Global Warming and all this will be redundant.

QrizB

curlylegend said:

... it looks, as though we've been sold something that doesn't work very well.

Engie ... took one look and confessed that they knew nothing about that make and couldn't help.

This surprises me a bit. Carrier are a huge multinational manufacturer of heat pumps, air conditioning and refrigeration equipment. Perhaps they just aren't big in France?

I hope you can get through the rest of the winter without too much discomfort. Maybe you'll have more luck finding a Carrier agent this year.

MultiFuelBurner

curlylegend said:

Thank you all so much for your helpful replies and comments. 
Despite getting quotes from seemingly respectable outfits it looks, as I suspected, we've been sold something that doesn't work very well.
The big problem I see in this area is that there are no genuinely knowledgeable installers. Engie, a big national organisation came in to see if they could do something, took one look and confessed that they knew nothing about that make and couldn't help. Apart from ripping it out and installing theirs. 
I wasn't exactly filled with confidence so declined the offer. And the original suppliers are just fobbing us off. Who do you complain to ?  Don't forget, we're in France where they invented and have perfected Bureaucracy ! 
For a couple of months we were compelled to use portable electrical fan heaters. If you could stand the noise they certainly got the room warm enough but cooled down rapidly as soon as they were turned off. And they gobbled electricity !  
We did at one point consider removing all the radiators and replacing them with ceramic cored electrical ones and just having the house centrally heated by electricity. All the estimates we were getting were telling us that it would be much more expensive to install and run than having a heat pump fitted.
So we'll soldier on, it won't kill us. We might even see Global Warming and all this will be redundant.

As the manufacturer makes much more powerful units it would be worth your while finding a specialist in Carrier heat pumps and getting their opinion and it could be as simple as an outside unit swap and maybe some larger radiators.


Personally I would contact the manufacturer directly and get them to advise of the nearest certified installer

https://www.carrier.com/commercial/en/uk/about/carrier-europe/

Swipe

Spoonie_Turtle said:

MikeJXE said:

LOL 

First I read EVs are freezing up and can't be charged

Now heat pumps are freezing up and won't keep you warm 

 Oh and trouble with some smart meters 

What next ? 

I'm glad I stuck to my ICE car and gas boiler 

This is only because it's clearly underpowered and possibly badly installed.  Have any of the owners of heat pumps in Britain on this forum complained of their pumps freezing?

Doesn't Matt_Drummer have freezing issues too?

matt_drummer

Swipe said:

Spoonie_Turtle said:

MikeJXE said:

LOL 

First I read EVs are freezing up and can't be charged

Now heat pumps are freezing up and won't keep you warm 

 Oh and trouble with some smart meters 

What next ? 

I'm glad I stuck to my ICE car and gas boiler 

This is only because it's clearly underpowered and possibly badly installed.  Have any of the owners of heat pumps in Britain on this forum complained of their pumps freezing?

Doesn't Matt_Drummer have freezing issues too?

I did have freezing issues but not any more.

It still has to defrost from time to time but they all do at these temperatures with high humidity, it is practically unavoidable.

As designed by my installer my system would never had worked, 50c flow at -3c was never going to be possible. The heat pump would never run for long enough to get the water to 50c before it needed to defrost.

I changed all my radiators for what I should have had, what I originally worked out they needed to be, they are nearly three times the size of what I started with.

Today, at -4c my flow temperature is 33c and the defrosting is about once every 90 minutes and much less severe than it was, it is over much more quickly.

The heat pump isn't working so hard so less air is passing over the evaporator so the ice takes longer to form and longer before the heat pump needs to defrost.

Even at -4c and 23c in the house my COP is just under 3, pretty good.

We used 36kWh yesterday to heat our 100m2 house and 15m2 all glass conservatory to 23c downstairs and 21c upstairs. I am quite happy with this.

My heat pump is grossly oversized and I actually turn down the flow temperature as it has got colder, I am still running at the minimum output.

Now that we have established that my heat loss at the design temperatures is about half of what the installer calculated (as I have always maintained) the heat pump is going to be swapped for a more suitable model.

In the cases here, it is not necessarily that the heat pumps are too small, it is almost certainly that the emitters are too small requiring too a high a flow temperature to get the house warm enough, it will always be a struggle to get high flow temperatures in freezing conditions.

MultiFuelBurner

As @matt_drummer says they all freeze up and that's normal operation which of course will be foreign for those without a heat pump and only used to gas.

As we have discussed in this thread on the information available the heat pump is undersized and the OP needs to take steps to rectify this is.

Our 8.5kwh heat pump 170m2 house (designed with heat pump and high EPC insulation in mind) yesterday sat at a flow of 35oC for 24 hours and used 28.5kwh. Toasty explains the temp 21-23oC all over the house 24/7. It ran defrost cycles as required. Because we have a smart meter our price was 16.92p kWh yesterday so the heating cost £4.82 (excluding SC but including VAT) from the local weather station 1 mile away we dropped to -6oC overnight and maxed out at 2oC during the day dropping to -3oC before midnight. (We record the weather as well)

Strummer22

@matt_drummer sorry to hijack the thread somewhat, but I take it your system doesn't have a buffer tank? Do you have room for one?

I ask because, to my mind at least, it would solve your problem, not that it needs it now you've resized the radiators. The heat pump could operate at or near minimum load to heat your buffer tank and radiators, then when buffer tank reaches temperature the heat pump would turn off and the heated water circulate in the central heating until the temp in the buffer tank decreases by some preset delta T (6°C, say), which given how efficient your house is might be several hours, then repeat. No short cycling, and no loss of COP due to nowhere for the heat to go, given that it would be going to the buffer tank. Just curious if you considered this option or you have it already and it didn't work for some reason.

matt_drummer

Strummer22 said:

@matt_drummer sorry to hijack the thread somewhat, but I take it your system doesn't have a buffer tank? Do you have room for one?

I ask because, to my mind at least, it would solve your problem, not that it needs it now you've resized the radiators. The heat pump could operate at or near minimum load to heat your buffer tank and radiators, then when buffer tank reaches temperature the heat pump would turn off and the heated water circulate in the central heating until the temp in the buffer tank decreases by some preset delta T (6°C, say), which given how efficient your house is might be several hours, then repeat. No short cycling, and no loss of COP due to nowhere for the heat to go, given that it would be going to the buffer tank. Just curious if you considered this option or you have it already and it didn't work for some reason.

Hi,

I think to some extant a buffer tank would make the oversized heat pump easier and better to live with.

It is something I had thought of briefly but my heat pump is grossly oversized and it is just simpler to replace it with something smaller and keep it simple.

The heat pump I have now puts out around 4.5kW of heat at it's minimum electrical input even though it is only a 9kW heat pump. This is because the heat pump is really a 16kW heat pump that is software limited in maximum output.

I often get three or four times the heat the house needs and it's difficult to live with.

The heat pump I have now has to go, it is just way too much for the house, the reality is that it is -4c here today and I I only need 4.5kW of heat to keep the house at 23c, the same amount of heat I get when it is +14c outside.


Thank you for the suggestion though, it's a decent idea.