Frozen Heat Pump

the_lunatic_is_in_my_head

Our first winter with a heat pump and it is very cold here (around minus 10 last night).

The back of the pump has frozen over:






One side has rather a thick covering of ice.



Is this normal? 

Online reading suggests it should run a defrost and low refrigerant could be an issue? 

It's a 12kw 6th Gen Samsung. 

Thank you in advance for any advice. 

Reed_Richards

It most definitely should run a defrost cycle, although at -10 C the air should hold so little moisture that there shouldn't be much frost forming.

If it's a monobloc then defrosting works by drawing heated water from inside the house.  Does your system have a buffer or volumiser tank?

the_lunatic_is_in_my_head

Reed_Richards said:

It most definitely should run a defrost cycle, although at -10 C the air should hold so little moisture that there shouldn't be much frost forming.

If it's a monobloc then defrosting works by drawing heated water from inside the house.  Does your system have a buffer or volumiser tank?

Thanks for replying, there is two expansion tanks and the hot water cylinder so unless it's incorporated into the hot water cylinder I don't think we have a buffer or volumiser tank.

Tends to be on the damper side where we are, lack of moisture in the air is often a rarity. 

QrizB

Is the heat pump still working & supplying heat to your home? Or is your home now getting cold?

Any error codes on the heat pump controller?

the_lunatic_is_in_my_head

QrizB said:

Is the heat pump still working & supplying heat to your home? Or is your home now getting cold?

Any error codes on the heat pump controller?

Thanks QuizB, there's no error codes on the display and the pump is working, just not as efficiently as it should as the air isn't flowing well due to the ice.

I only noticed as the hot water wasn't up to temp after it had been on for an hour (we turn the HW on as we need rather than all time), heating has dropped 0.5 below the thermostat (again due to the lack of efficiency), main issue is electricity consumption yesterday was very high.

I've simply turned it off for now as I don't want to over stress the pump, not worried about the heating or HW, we have a wood burning stove to keep warm, just wanted to make sure the pump wasn't suffering from a problem or whether this can be expected in such temperatures. 

FlorayG

Is it Normal For My Heat Pump To Ice Up in Winter? - Davis Heating & AC

QrizB

As R-R says, the heat pump should run a defrost cycle when it gets like this. That makes me wonder if something isn't quite right with it, despite the lack of error codes.

I don't know enough about your specific heat pump to give any pointers, sorry.

matelodave

Turning it off is probably not the best idea, they fare a lot better when they are left to do their own thing rather than keep faffing around with the controls or turning it on an off. TBH the worst thing you can do is turn it off, let it get stone cold and then try and fire a slug of frozen refrigerant through it when you try and restart it - that could easily damage the compressor.

Of course it going to be less efficient when its everso cold, so is a gas boiler as they have to put a lot more effort in heating the place.

My 11kw Daikin unit is now over 14 years old, and when its cold and damp it frosts up and then every now and then there's a great gout of almost steam as it defrosts. It was around -6 here last night but we have had instances where its dropped to -14 in previous years and, yes it can look a bit scary when it's frosted up, but leave it alone and it should sort itself out.

We chewed through around 47kwh yesterday for all our electricity (about 37kwh for heating) and it ran for 24 hours and we still woke up with a warm cozy house and a tank full of hot water

We have the hot water timed for two hours a day although it usually takes an hour or less to reheat but a bit longer at this time of the year when the incoming supply is colder than normal and the heatpump has to work a bit harder.

Once it's got up to temp, it reverts to heating and wont reheat until the next day. It then it stays warm enough for all our need right through to the next morning. Is your system set to hot water or heating priority? as that can affect whether you get enough hot water before the heating kicks back it.  

Mine looks exactly like yours when it's frosted and I've seen it look like a winter wonderland when it been ever so damp and foggy as well. Wait till you get several inches of snow on top or blown into it as well - it still works and still produces heat  although probably not quite as much as on a sunny warmer day.

.

the_lunatic_is_in_my_head

Thanks both, yes the lack of defrost was what concerned me, just wasn't sure if it was too cold and expecting a defrost was unrealistic (or this model doesn't have that feature although I think generally modern models do). 

Manual says there is an error code for faulty outside temp sensor so without that error code being displayed I can only assume the outside temp sensor is working (the heap pump does generally run at a higher Kw when it's colder anyway). 

I'll pop the photos over to the installers on Monday and see what they come back with. 

QrizB

the_lunatic_is_in_my_head said:

I'll pop the photos over to the installers on Monday and see what they come back with. 

It's due to warm up from Sunday, so with a bit of luck it'll have thawed itself by then!

matelodave

It would probably thaw itself if you stopped fiddling with the controls  .

Have you got TRV's on your rads as well. If so they'll reduce the volume of water going round the system which will reduce the system capacity to defrost.