LG Smart Load Control feature

Hey everyone, over the last 3 years possibly even longer you have been aware of the issues with my LG multi system (FM25AH UE1). Well I am pleased to say that LG have now fitted and supplied FOC a new outdoor unit (MU4M25 U43). Its taken me a long long time and a massive battle to get a resolution with me going really high up within the air con section to get a result. They kept saying that there was no fault despite me spending a fortune on visits and carrying out various diagnostics. In the end it came to light after much testing at their end that my indoor units were not compatible with the outdoor unit due to age. Even though this was fully checked out at install that the new indoor units would be fine with the FM25.

Anyway a question as this new outdoor unit is working fine and seems packed full of energy features, what is this smart load control that is on the outdoor unit dipswitch and why would I need to set it, shouldnt this be in operation automatically as part of the control strategy? The install engineer from LG enabled this mode and it seems to ensure that the air off does not go above about 44C and seems to maintain closer to the set point rather than the unit wanting to cycle off. I might try it without it on to see what we get. Mitsi and all the others dont promote this feature as I assume its already built into the logic and isnt selectable. The LG units now have a pressure sensor that detect the system pressure to respond faster etc. See picture below:

Attachment 13927

LG say:

"The logic is quite simple: The built in micro processor monitors the coil temperatures and room temperature, and it knows the room temperature set-point.
As set point is approached, the capacity of the unit is reduced by reducing the temperature difference between the indoor coil and the air. This is done by adjusting the compressor speed and the electronic expansion valve. Our systems now have a pressure sensor located to measure suction pressure in cooling, and discharge pressure in heating, which facilitates a faster response to changing conditions."

Let me know your thoughts. Smart Load control is now apparently on all the 2015 models.

Kind Regards
Richard.

Hi Richard,

Great news, took a while and a bit of a hard one for anyone but LG to diagnose without taking a punt so glad you got there.

Seem to recall software problems on their VRF and central remote back in the day. Cost contractors, wholesalers and LG a fortune and a legacy which still sticks. Even the VRF design program would spill out different wiring depending on which update you had. Net result could be that a system was installed but comms wired up star instead of daisy chain (or something like that) and needed to be rewired to work. Let's not LG bash too much though as every manufacturer has skeletons they'd rather best keep hidden.

LG Smart Control looks like a gimmick to me. For true energy saving you need to stick the air on probe in an endocube! Seriously, all manufacturers sales blurb has the same blocky charts claiming great energy saving compared to the last model. Inverters I guess are pretty efficient, bit hard to squeeze anymore major out of them. This is all just fine tweaking the control which I doubt would have much financial impact and unless you if intend to temperature map a room for accurate control then a split really isn't the man for the job.
Better temperature control for the room? Well for some maybe but then we've all heard the story of the fussy office worker always moaning about the AC, thermostat screwed to the wall and they're told this now works the AC and all theirs to control. Worker well chuffed but in reality thermostat isn't even wired in. Placebo. Ha, or am I too cynical?

Generally inverter speed is defined difference between set temp and air on. EEV generally set to control discharge temp (for a split). Sure, a manufacturer can muck about to fine tune this by taking into account other temp probes, fan speeds but really, is anyone really going to notice? Stick a pressure sensor on to make the measurements a bit more accurate still, that's progress for you! Cynical me says more to go wrong!


Still, I'm going off track a bit. Why not try it with or without and see if you notice any difference. Not with a thermometer but just in day to day use.

Hope you get on well with the AC, hope it behaves!

Andy. :-)

Ok with it off it seems to achieve set point a lot quicker with an air off of approx 50-55c. With it on it seems to have an air off of about 40-45C modulating up and down so whilst it takes longer to reach the set point it seems to keep the temp smoother rather than cycling off or getting blasts of really hot air. Deffo uses less power as well.

Happy new year to you all. The system has worked well and cheap on electric but I've a couple of queries that have come up over how the system behaves when compared to the previous one. Hopefully someone can help.

1. When units are first turned on from being off overnight. The outdoor unit doesn't start up for best 4/5 minutes, it's then further 3/4 minutes before starts blowing warm air. Is this normal? The previous outdoor unit started up as soon as an indoor was turned on within 20 seconds. LG advertise that it is just 3 minutes before the air starts blowing so you assume this from the point you turn an indoor unit on, the reality at the moment is nearlly 10 minutes.

2. Unit heats to 4c above the set point then thermostat off which is well known in heating. Eg 19c on controller room will heat to 23c then go off. If OD unit is not already running room then has to drop to 21c before it comes back on so a 2c drop. If OD unit already running because another room or rooms are at thermostat on then room only drops 1c to 22c and indoor will kick back in again at thermo on so wondering why 2c drop when outdoor off but why only 1c when outdoor already running? As I say just need to understand the logic as the 2c drop is quite a large drop to feel in the room before it comes back on. Just need to understand though why when the outdoor unit is already running this changes to -1c of set point and only becomes -2c when the outdoor is fully off. The outdoor is very efficient but unsure as to why thermo on sometimes occurs at -1c and other times -2c leading to you feeling chilly if it's the -2c one. If outdoor already running then it's 1c but you say this should be -2c? Maybe the new outdoor realises the -1c and provides heating to maintain the temp better and to reduce on/off cycles for efficiency. This is last nights example: The units all reached set point last night and cycled off as expected. Because the outdoor was off for some time the system would not come back in until at least one room had dropped by 2c. 3 rooms apart from one all had a 1c drop, when the 4th room dropped by 2c the outdoor fired up and all 4 indoors came on at thermo on even though only a 1c drop in room temp in those rooms. Need to understand this as there could be a fault still maybe with the sub boards.

Kind Regards
Richard.