Re: How much power should it be using in heating?
The cheap kit from Korea like LG is cheaper than other eqipment for a number of reasons.
They can easily copy metal & plastic parts & make the unit look any other but its more difficult to copy the control stratagy & control circuit boards. So you will tend to find that the control circuit boards are simplified & control stratagy is basic.
This helps to make the kit cheaper to manufacture.
They tend to sell most volume in very hot parts of the world. So the design department at the factory are not so focused on heating performance & heating control stratagy.
The product is basically a cheap cooling system with heating as a bonus.
The koreans brand the product very well but its never going to be as energy efficient as other brands unless they develop the product with more advanced contol. But that would make it more expensive & they would loose sales.
Look on the Eurovent web site & compare the data of this product with others & you will see that its not the most energy efficient kit in the world.
Hendra will give another spin on this but then his job depends on maximising sales of the product.
Re: How much power should it be using in heating?
So for instance
Quite a few split systems have a minimum compressor run time of say ,,, 3 mins. This is programed into the system control stratagy.
On older fixed speed compressor units that had no oil seperator at the outdoor unit the manufacturers opted to make a minimum compressor run time to ensure oil return as the oil had to go all the way arround the system & back to the compressor.
Unfortunately if the unit was oversized which is common for heating mode when the system has been selected for max cooling duty, then the unit could overshoot the set temp before completeing the min comp run time.
Ofcourse this is not an issue on larger VRF systems which have oil seperators which are 99% efficient. But manufacturers of budget split systems need to keep cost as low as possible so the compulsary min run time is an easy option rather than install oil seperator.
I did overcome this problem a few times by fitting a time delay relay to the compressor contractor.
The min compressor run time is based on the max allowable pipe lenght & so if you have short pipe lenght then you can risk a shorter min comp run time by fitting the time delay relay so the comp will only run for 2 mins instead of 3 mins.
Ofcourse this makes the warrantee invalid & you risk stuffing the compressor.
You might find that your unit will run the compressor for a fixed speed for a number of mins. At the end of this period the circuit board then looks at the return air temp & the indoor coil temp & makes a decision what to do next. If the temp is near to set point then it may ramp down the comp. But if its has already reached set temp or overshoot then it will stop the comp.
So in this part load situation the compressor never gets to ramp down.
I dont have detailed info on LG units control stratagy so this might or might not be whats happening on your system but it is something I have seen a number of times before on a number of different types of split system.
Unfortunately with inverter systems it would be difficult to overcome this unless the manufacturer has some dip switch or function setting options & with budget a/c kit thats not very likely.
Re: How much power should it be using in heating?
And for instance
Multi split systems tend to incorporate a safety feature which prevents the accumulation of liquid refrigerant & oil in any indoor unit not heating.
It works like this.
Any indoor unit which is off or thermostat off at set point will not completely shut the liquid line LEV valve. So a small volume of hot gas passes through the indoor coil.
This makes the indoor unit produce a small amount of heat & in a small room this can provide some heat to the room even though the unit is off.
This control stratagy prevents hot gas from condensing in the indoor coil which would make the system seem short of gas & trap some oil also.
This might seem to be incorrect operation to the end user but it is the control stratagy programmed into the electronic control to prevent compressor failure from trapped liquid & oil at any indoor unit at off.
Re: How much power should it be using in heating?
Thermatech I have read all your comments and it seems that it is possible that its not getting chance to ramp down. Average compressor run times per cycle is about 10-15mins so its deffo not the min run time thing kicking in. It doesnt short cycle in the sense of starting then shutting off straight away, it actually has to work to bring the room temp back upto set point. The concern is that it surely winds up to the capacity it needs to be at based on room temp. If thats just one degree below set point does it really need to run at full speed to get the temp back up. I was sent something from LG that said that if the temp is 3 degrees lower than set point then it runs at full speed and as it comes to set point starts slowing down. There is no way the room temp is going over the set point in 3minutes it takes about 10mins in this weather before it reaches the set point then carries on going at full speed for another 5minutes until it runs over the set point.
Re: How much power should it be using in heating?
For most inverter split systems once near set point the compressor will ramp down & hold room temp within 1 deg of set temp.
It should only switch off compressor if at minimum speed the heat input to the room still makes the return air reach set point.
If the compressor carries on at high speed until it hits set temp & stops then its working more like a fixed speed compressor unit.
If it overshoots then perhaps the return air sensor is reading a bit low the manufactuing tolerance for the sensors will only be + or - 1 deg C at best.
The remote sensor option with sensible sensor location might help.
Dont expect too much from this type of equipment.
Keep the fan heater ready as backup.;)
Re: How much power should it be using in heating?
Really is it not that reliable. I am told by the installer and some other people that LG isnt that bad equipment and has vastly improved.
Do you think the remote sensor will communicate with the outdoor unit better?
The return air sensor has been checked in both units, one of them was faulty originally and we tested it and it was about 1C out so if the set point was 20, it was cutting out at 22.
Now they are both accurate to 1C so if set point is 20 its cutting out at 21 which is correct. Surely the 3C margin that is giving for compressor to start ramping down should start when the return air is climbing past 18C on a set point of 20C, Or does it only start ramping down when it gets to 20C to try hold thte 20C? As its currently shutting off at 21C with no evidence on the meter to show its ramping down at 20C, as it is continuing to stay on for another 5minutes at 20C until it reaches 21C.
Re: How much power should it be using in heating?
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Notwithstanding all the posts, why are you on a pre-payment meter?
You are paying far more for your power that way.
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Re: How much power should it be using in heating?
Because the flat is rented from a private landlord and he has them on a coin meter. I know we will be paying more but the wattage still goes through the energy meter the same, im not really looking at the cost im looking at the actual wattage consumption.