LG Therma V - Help

[jkh2022]

Morning, 

 

Right strange one unit has been installed and working fine for the last couple of months but recently when the unit shuts off we've noticed a loud bang which I could only describe as a plastic bottle when it pops.

 

That has got slightly louder but yesterday evening I noted the UFH calling but not getting warm. 

 

It is a 300 LTR preplumbed cylinder so the zone valve opens when DHW is calling which is working as it should but what I've found even when the DHW is calling there is slight heat leak through the buffer tank and this then starts rising up the ufh supply pipe it doesn't get to any of the manifolds due to the ufh pump not kicking it but it's extremely warm but when I ask for the ufh to be on nothing changes apart from the ufh pump kicks in and all the heat goes around the DHW side. 

 

Also I noticed yesterday it was calling for UFH but when I went outside the fans where completely still not moving at all.

 

I turned the unit completely off at the main isolation switch for 30 min turned it back on and the fans started again but with all the above issues still. 

 

As I say its been working absolutely fine and impressed with it but last week it's become a nightmare as no heating in the house at all. 

 

Anyone any ideas. 

 

Thanks

Edited May 1, 2023 by jkh2022

[ProDave]

Do you have a plumbing diagram?  What motorised valves(s) are there on the heating side?  Post some photos of the pre plumbed tank and UFH manifolds.

 

It sounds like the heating 2 port valve (assuming there is one) is not working.

 

Mine is an older version of the therma V and the heat pump controls the motorised valves. If the more recent ones are the same you need to determine if the heat pump is trying to turn the valves on?

 

If it is this recent, what does the installer say?

[ReedRichards]

I have a third party controller for my LG Therma V.  This restricts the number of cycles per hour (to 3 cycles).  It can happen (although not very often) that my room thermostat is calling for heat but the controller is waiting for the allotted time to start another cycle so the fans and the heat pump internal water pump are off.

 

I never get bangs or pops.