LG Therma V R32 Split - Frost build up

[DustyBin]

Hello,

 

I have recently had a 12kW heat pump installed, and it has been running for around a month or so now. However, this morning, I was surprised to see a large build up of frost over all the fins of the outside unit, despite the outside temperature being around 5 deg C (minimum). I would have expected the defrost cycle to kick in to remove this ice build up, but so far it has not done so. Does anyone know the conditions it uses for triggering the defrost cycle, and whether this can be managed in the settings?  If it is triggered purely on temperature then I am not too surprised that it has not kicked in yet, but I guess it must also be related to humidity.

 

For the moment, I have just knocked the thermostat down to let it defrost naturally, but I am worried that may be a malfunction somewhere.

 

Thanks for any insight any of you may have on this matter.

 

 

 

 

[ProDave]

The worst time for icing is when the air is a few degrees above freezing, the heat exchanger will be colder and in this case below 0.

 

Once the air gets below 0 for any length of time there is little moisture left in it, so almost counter intuitive, there is much less chance of icing.

 

I have an older version of the monoblock ASHP and there are no user adjustable parameters relating to defrosting.  And nothing published about how it decides when to defrost.  I would be inclined to just let yours get on with it if nothing else to see if the defrost function works.

[JohnMo]

3 minutes ago, ProDave said:

have an older version of the monoblock ASHP and there are no user adjustable parameters relating to defrosting.  And nothing published about how it decides when to

I just looked at my technical manual (different make) it also say nothing much, it says there is a defrost and does stuff, but nothing you can adjust. Mine was defrosting last night, and the fins on the condenser looked completely blocked before it defrosts. A good even later of frost.

 

What mine does say is it doesn't defrost in DHW heating mode, it waits until the end of the heating cycle. 

 

Could yours have been in DHW mode?

[ProDave]

If anything I would say mine defrosts more in DHW mode as it is generally working harder then.

[DustyBin]

Hey all,

Thanks a lot for your replies (I just noticed them  )

My heatpump is not used for DWH, only for central heating, so not related.

It was running in Manual mode (where I set the water temp), and I switched it to Auto mode, and it did go ahead and run a defrost cycle. I am not sure if they are connected, but having said that there is an issue with Auto mode so I went back to Manual. The icing has not occurred since.

I will keep an eye on it, but it does seem to be ok.

Thanks again

 

[ReedRichards]

On 16/11/2023 at 12:18, DustyBin said:

there is an issue with Auto mode

Auto mode gives you Weather Compensation.  If there is an issue it may be that the parameters that set the Weather Compensation line are not correct.  You can change these in the installer settings.

[JohnMo]

On 16/11/2023 at 12:18, DustyBin said:

having said that there is an issue with Auto mode so I went back to Manual. The icing has not occurred since.

The amount of frosting is directly related to the flow temp of the water and outside temperature. The more work you ask the heat pump to do (i.e. hotter flow temperature) for a given outside temperature the more likelihood of frosting up.

 

So as @ReedRichards says perhaps the WC is just set wrong.