UPDATE - LG Attended Yesterday:

Very friendly and knowledgeable chap... arrived at 8am.

The man connected a laptop, checked all sensors and found that 2 of the indoor units had loose connections on the board where the sensors connect. This could cause the unit to throw up an error code showing that the sensor was missing/shorted (never happened) or it would raise the resistance and give false readings back to the outdoor unit. He is to arrange replacement sensors to fix this.

Checking over the outdoor unit all sensors were ok on here... the outdoor air temp sensor had a plastic sheath round it and he said this will cause the sensor to be out as the air wont get to it (I disagree it may slow down reaction time by a few mins, nowt major though). So he cut that back so the sensor itself was in the air directly. The laptop showed that valves were operating etc and nothing stood out as not working properly but what the laptop doesnt show is if a valve is stuck as the system doesnt have sensors to show that a valve isnt operating correctly. I queried this but he said that it would stick out like a sore thumb on the readings. (dont think it would if it was a fraction not closing properly) EG laptop would show valve at 30pulses but what if it was at 20 or 40 pulses this would let too much or too little through.

He then did a calculation of the pipework and he says the unit is short of 220grams of gas. Strange as defrost cycles are few and far betweena and when it does the timed 5 hr oil return cycle there is never any ice built up on the outdoor unit. I queried if this would make much difference he was adament that it would cause an issue of poor heating. What I dont understand is that when the unit does a defrost or a oil return cycle and goes back into heating the heating performance and air offs are very good until the next cycle when they are back to being poor at 32C or so. Even putting it upto 30C they go up a by a few degrees but not much.

As soon as I turn another unit on the performance is good, we get good air off temps.

My engineer is going to come back and reclaim refrigerant through a drier and weigh it out to see whats in it as possibly short of refrigerant (why no freezing up of outdoor unit though?) if its short will need new refrigerant as I understand the gas is made up of different components.

Is there any logic in this email I sent to him this morning: What do you think:

"Very poor heating again this morning, only 32C air off in lounge (unit drawing 1.2kw), then the unit went into oil return mode (not defrost as its 6C outside and no frost on the coils) and 5 minutes later it is blowing air out at 40C and compressor drawing 1.6kw, is this a sign of it being undercharged such poor heating till it does oil return? Just funny how as soon as its done oil return I get good output. Also the fact that when two units are running means compressor is pumping harder to so if it is short of refrigerant how do I get better output when two are running as there is still the same amount of refrigerant isn’t there."

Let me know guys... hoping that it just a gas issue as its going to be an expensive winter when it gets really cold again (fan heaters etc)