First post, please be nice, prob with heat mode

[back2space]

Not sure really I wouldnt be able to do this anyway if it was possible.

I think the best thing to do is get the sensor mounted further away from the unit.

Question is how can i get this done!

[Tradewinds]

Hi Back 2 Space,
Please bare with me as I don't work on splits (much) and haven't posted here for quite a while, so you could say I'm a bit rusty. Personally speaking, I would definitely look to relocate the sensor. I would have thought that LG have a remote sensor available for this unit or failing that any electrician could extend the cable for you. It's interesting though that it doesn't vary the compressor speed on heating as well. I would have looked for a DIP switch to correct this as well. Is it the same problem on both indoor units? You could also try putting the sensor in ice to see if it runs for more than 4 minutes. This would indicate whether it is stopping on temperature or fault (if no fault indication is present).
Hope this helps,
Regards,
Stuart

[back2space]

When i touch the sensor with warm fingers the unit will switch off. We have measured the intake temp and this is always about 1c lower than the actual room temp, i assume because of the high ceilings the floor is always going to be cooler.

The sensor is therefore working correctly. The unit varys comppressor speed in cooling and i assume it is doing so in heating although maybe because it is oversized it cant slow down enough.

LG say there is no remote sensor for this model and that they would charge for an extension of the sensor! Hardly fair!!!!

[nike123]

When i touch the sensor with warm fingers the unit will switch off. We have measured the intake temp and this is always about 1c lower than the actual room temp, i assume because of the high ceilings the floor is always going to be cooler.

The sensor is therefore working correctly. The unit varys comppressor speed in cooling and i assume it is doing so in heating although maybe because it is oversized it cant slow down enough.

LG say there is no remote sensor for this model and that they would charge for an extension of the sensor! Hardly fair!!!!

Who has made decision for indoor unit position? You or them?
If you insisted that it must be there, then I don't see how is that not fair!
If they are insisted with placement of unit there and did not tell you about possible difficulties with room temperature control, then they are responsible.

[back2space]

They told me where they were putting the unit as this was really the only place to put it with the outside wall, its a victorian house and it kept pipe runs to a minimum as well. If it had been mounted anywhere else in the room on another wall i think it would have been the same problems. There a no draughts from the windows at all and the unit behaves fine in cooling but it seems that the hot air is taking longer to fill the room due to stratification so taking longer to circulate to the lower floor area. if the louvre is set to move up and down itself then the unit reaches set point very quick but the actual room temp is lower than the unit thinks then due to warm air cycling back into the unit.

[Brian_UK]

I assume being a Victorian house that you therefore have quite high ceilings.

If this is the case then there might be a valid argument for installed a ceiling fan the destratify the air.

If the fan is used to draw the air upwards then the warm air is circulated without draughts.

[airefresco]

I was just going to suggest the exact same thing as Brian.

[back2space]

I assume being a Victorian house that you therefore have quite high ceilings.

If this is the case then there might be a valid argument for installed a ceiling fan the destratify the air.

If the fan is used to draw the air upwards then the warm air is circulated without draughts.

Yes we have the high ceilings and we also have a ceiling fan in the said rooms, the bedroom unit seems to reach temperature better but this is mounted about another foot higher from the floor than the lounge one (problem one)

The bedroom one is fine even without the ceiling fan on.

If the lounge one is operated with the ceiling fan in reverse then we end up with an even worse a situation as the air is sucked upwards and thrown down the sides of the walls thus cooling it at the same time.

[Brian_UK]

I really do get the impression that that unit is well oversized.

The hot/warm air being lifted by a ceiling fan should not really create a major change of effective temperature. Unless, the air is being heated in chunks (wrong word but can't think of a better one).

This is always the drawback of blown warm air heating, as soon as the temperature of the supply air changes everybody notices.

[back2space]

The unit behaves perfectly in cooling however still cycles on and off, i dont think it can ramp down enough.

We had various quotes, most quotes said we needed 12000btu unit for cooling, however one firm said a 10000btu unit???

Obviously in cooling the indoor unit (MV12AH outputs 3.52kw of max cooling, however in heating it seems the max output increases to 3.87kw so slightly higher. See link and scroll to specs.

http://mylg.co.uk/data%20for%20site/...onvertible.pdf

Now when you compare this to the min/max outputs of the the outdoor unit, the max rated capacity of the outdoor in cooling is 8.5kw and the min capacity in cooling is 1.85kw whereas in heating the max is 9.38kw and the min is 2.22kw.

Now it does say that the unit should be able to ramp down to 2.22kw which is 6300btu. Surely if the one guy said 10000btu was needed for cooling then similar capacity is needed for heating.

Starting to get confused with the figures but i know the unit is oversized but we need this extra capacity as when we have friends over we have a full room then the unit doesnt tend to cycle it will ramp right down in cooling.

HMMMMM me confused you all now i bet!

[back2space]

the above details are for the multisplit system that I have. The indoor units are the same as the type I would have if it was just a standard back to back split.

Now what I have also looked into is the min/max ratings of standad back to back 3.5kw inverter split condenser unit. (1 indoor 1 outdoor)

I notice straight away that the standard 1 on 1 split can ramp its capacity down lower than my multi split condenser.

Cooling min = 1.40kw
Heating min = 1.62kw

So if on my multisplit condenser it has ramped right down to 2.22kw in heating and this is still too much for the room its going to cycle off isnt it. In cooling its cycle on is longer than a cycle in heating.

Another worry is how do inverters handle short cycling issues? i know standard fixed speed ones wear out.

In heating the unit cycles on for 6 minutes and then its off for about 20minutes.

In cooling it will be perhaps 10 mins on and then 10 mins off.

[murran]

Hi, I am new to the forum.
I do not have a lot of experience with multi splits as ive worked mostly with larger industrial airconds.
Ive read through all the info and what I can add is the fact that the aircond is at ground level will influance the heating capacity in particular due to the fact that heat rises.
The temp at celing will be easily 3C higher than floor level. This means that by the time setpoint is reached at floor level where the sensor is situated the room temp will be a few degrees higher.
To compensate for this you could set your thermostat at least 2 degrees lower than what you want instead of moving the sensor.
The fact that it is running at full capacity for a short period suggests undersized unit.?
The other factor in heating cycle is the outside temp.
If it is very cold,the unit will ice up(this is normal) and goes into defrost cycle shutting down the heating for short periods.
The best solution in my opinon is to relocate the aircond to ceiling level & to make sure you have sufficent capacity condensor.

Hope this helps.

[back2space]

Hi Murran

Welcome to the forum, thanks for your input, everything so far is leading to the unit being oversized as it does not struggle whatsoever with heating the room at all in fact it is overheating the room, cooling likewise however precision temp control on cooling mode probably due to the way cool air circulates back to the unit.

THe unit has never gone into defrost mode yet hasnt been cold enough does a oil recovery thing every 6 hrs though kind of like defrost operation but theres no icing up.

We think the unit is operating at high speed when it kicks back in at thermostat on but the room is heating up quicker than the inverter can adjust to conditions so ends up cycling off.

We tried compensating with lower set point (20) and found that whilst the temp at cycling off was more suitable (22). The unit would then not kick back in till the room temp had actually dropped to 19C so there was a big diff in temp, not ideal for a lounge.

[SteinarN]

They told me where they were putting the unit as this was really the only place to put it with the outside wall, its a victorian house and it kept pipe runs to a minimum as well. If it had been mounted anywhere else in the room on another wall i think it would have been the same problems. There a no draughts from the windows at all and the unit behaves fine in cooling but it seems that the hot air is taking longer to fill the room due to stratification so taking longer to circulate to the lower floor area. if the louvre is set to move up and down itself then the unit reaches set point very quick but the actual room temp is lower than the unit thinks then due to warm air cycling back into the unit.

What you want is the unit to cycle off quicker. Iow a shorter heating cycle. You mention the solution yourselv in the quote. If the overall room temperature then gets to low you have to increase the set point until you acheive the correct room temperature.

Generally speaking it is impossible to acheive an even heat distribution in the room without the direction of the air flow be either horisontal or downvard say 45 degrees. Downvard 45 degrees for ceiling or high wall inndor units and as close to horisontal as possible for low wall units. It is however important that no furnitures is in front near the inndor unit as this will cause excessive short cycling.

[back2space]

By short cycling what sort of lengths of time do we consider a short cycle?

My units cycle on for about 5-7minutes and then off for 20 or longer on the heat operation

In cooling its 7mins on and then off for ten minutes or a little less.

Do inverters wear out this way, is it bad for them?

[SteinarN]

With short cycling I ment the warm air returning back to the indoor innlet. I didn't have in mind the lenght of each heat cycle.

I dont think inverters wear out as as a result of frequent start-stop operations. There is no electric relays to wear out. Inverters starts very gently.

Try to adjust the louver to as close to horisontal as possible and remove the furniture away from the warm airflow.

[back2space]

We shall have to look into this as the airflap is already horizonatal at a 50 degree angle.

We shall see over the coming days or so.

[nike123]

We shall have to look into this as the airflap is already horizonatal at a 50 degree angle.

We shall see over the coming days or so.

What you mean by 50° angle?
From picture of that unit, its flaps can easily be parallel with floor. That is 90° angle with wall or 0° angle with floor.
What is your case? Could you post picture with flap position you usually use?

[back2space]

OK the unit is in heatnig at present and the flap is set as it automatically sets in heating mode. From the point of switching it on.

If the flap points any closer to the floor it short cycles even more as the floor area warms up too quick so this seeems the best angle.

U can see from "Untitled 3" the flap position in heating, automatically set, this seems to be the best position we have tried them all.

"Untitled" is a view of the room lengthways.

"Untitled 1" is a room widthways, the a/c blows widthways.

"Untitled 2" another view of the a/c.

[nike123]

From what you just said it is more likely that your AC is grossly over sized! Now it is important to find out your real heat loss in that (and other) spaces.

Ok, more questions!

Do you use only one of these two indoor units when you experience these problems, or you use both units simultaneously?
What is your typical outdoor temperature/humidity these days, and what is set indoor temperature?
What kind of windows 8describe construction of windows) in that lodge you have, and what is actual height of your room? What material is that curtain and how thick it is?
Do you have knowledge of walls construction details and do you have any drawing of conditioned spaces?
Does other three walls of room looking to conditioned (heated) places?
Do you have any additional (significant) heat source in that rooms?

[back2space]

The problems are experienced whether I use one or both units. We find though that 1 unit is sufficient enough to heat the entire flat up!

We tend to use both units when on cooling mode and no problems when on heating we can have problems when they are both running, the units are separated by another 2 rooms and are not fighting against each other in anysort of way.

The construction of windows are double glazed pvc windows (no draughts)

The height of the room is standard height for victorian house, not sure of exact height dont have measure but if i jump up i can reach it just! Im 6ft 2.

The curtains are thick blackout curtains to retain the heat, these problems happen whether the curtains are drawn or not.

The only outside walls are the side of the fireplace and either side of the window.

The other unit is installed in a similar room but is a little bigger (bedroom).


No significant heat sources in the rooms unless we have a party and have disco lights going and people dancing most of the time there are 2 or 3 people in there.

Thank you.

[SteinarN]

From what you just said it is more likely that your AC is grossly over sized!

This is probably the main problem asuming the outdoor unit is actually running at lowest possibly capasity in heat mode.

[back2space]

Yeh this seems to be the case!!! Thing is we leave all the internal doors open to the hallway and the unit heats the whole hallway and the other rooms perfectly and stil cycles on and off!

SUppose thats good really aint it!!! Id rather have it overperforming than underperforming.

[nike123]

The problems are experienced whether I use one or both units. We find though that 1 unit is sufficient enough to heat the entire flat up!

We tend to use both units when on cooling mode and no problems when on heating we can have problems when they are both running, the units are separated by another 2 rooms and are not fighting against each other in anysort of way.

The construction of windows are double glazed pvc windows (no draughts)

The height of the room is standard height for victorian house, not sure of exact height dont have measure but if i jump up i can reach it just! Im 6ft 2.

The curtains are thick blackout curtains to retain the heat, these problems happen whether the curtains are drawn or not.

The only outside walls are the side of the fireplace and either side of the window.

The other unit is installed in a similar room but is a little bigger (bedroom).


No significant heat sources in the rooms unless we have a party and have disco lights going and people dancing most of the time there are 2 or 3 people in there.

Thank you.

In my practice, I was been in situations like your now, but on opposite side. I am pretty sure that calculation of required capacity is not done scientifically , it is probably done by rule of thumb. Therefore such high discrepancy in really needed and installed capacity.
There is very, very slim chance that installer will consider that as his error.
My advice is, to do as I already suggested, and install sensor on appropriate place (described earlier).

[back2space]

Does the inverter run faster when it is in heating mode as apposed to cooling mode.

It seems considerably louder when in heating mode (sounds to run faster) even when it is only maintaining a setpoint of 22C and outdoor ambient of 13C.

Wheares in cooling it can hardly be heard, we thought this was fan noise as the fan runs faster in heating but its not it is the compressor is noisier and faster. When the engineer set it up he put multimeter on and it was drawing more current in heating than cooling?

[back2space]

Reason i ask is when I check the panel at work (Mitsi Elec) you can check the Hertz of the compressor. ANd when its in heating or cooling and maintainting setpoint happily the comp hertz are about 59-60hertz. Is

[Thermatech]

LG twin split system

Ebay item 230349810459

Looks familiar

[sinewave]

If in doubt, flog it to some other Sucker!


It's doing well at £32!

[back2space]

If in doubt, flog it to some other Sucker!


It's doing well at £32!

Its not like that at all.

The system works fine according to LG Technical, however the installer and myself does not believe that the control strategy is working as it should, yes it heats and cools aplenty but not as efficient and per the specifications that they sell the system on.

Would be fine for conservatories, shops or retail premises, however if its for houses/ I think you will have probs with temp control, either too warm, too cold and the system not ramping down as designed to leadiing to the system cycling off due to lowering the room temp too far below the 1C above or below set point.

Cheap tat I think the fact its at that ammount says what sort of influence they have on the market. No one wants them.

One chance and they messed up.

[Yuri B.]

Hello.

P 60. Now when you compare this to the min/max outputs of the the outdoor unit, the max rated capacity of the outdoor in cooling is 8.5kw and the min capacity in cooling is 1.85kw whereas in heating the max is 9.38kw and the min is 2.22kw.Capacities stated of systems are in the long run the product of ambients. Thus, the heating one of 9.38kW is reached by the system at the maximal outside temp (let's say +18C), 2.22kW at the minimal (allowable) outside temp (let's say - 20C). For cooling otherwise direction.


P 71. We find though that 1 unit is sufficient enough to heat the entire flat up!....... have problems when they are both running,As you have mild winters in Britain, heatpumps should work with maximal productivities.
Considered "oversized" at +13C outside (value mentioned by you, I think, not once), I bet you (would) have another point of view about the AC at -13C outside.

P 61. Another worry is how do inverters handle short cycling issues? I know standard fixed speed ones wear out.
In heating the unit cycles on for 6 minutes and then its off for about 20minutes.I think you are unduly worried about this issue. First, if it is invertor, no problem at all, secondly, agree, we do not change compressors very often at freezers working this way.

P 55. the unit reaches set point very quick but the actual room temp is lower than the unit thinks then due to warm air cycling back into the unitAs the coil's residual warmth keeps warming up the sensor, many here advised You to bring it some meters away. Having it "black-scotched" to an opposite wall - for an experiment - for a week would not give you more inconvenience than struggling with temp-s across the whole place. (then You would have redone it properly, of course).

What is left to do if the control may turn out to be far imperfect, if the position of the units seems to have been a bit better? Probably, experimencing with the sensor(s) and air flows (maybe even blocking air flows - depending on temp-s outside).

Best regards.

[Yuri B.]

Every quote is actually followed by my comment, however smth went wrong when posted.

[back2space]

Hello.

P 60. Now when you compare this to the min/max outputs of the the outdoor unit, the max rated capacity of the outdoor in cooling is 8.5kw and the min capacity in cooling is 1.85kw whereas in heating the max is 9.38kw and the min is 2.22kw.

Capacities stated of systems are in the long run the product of ambients. Thus, the heating one of 9.38kW is reached by the system at the maximal outside temp (let's say +18C), 2.22kW at the minimal (allowable) outside temp (let's say - 20C). For cooling otherwise direction.


P 71. We find though that 1 unit is sufficient enough to heat the entire flat up!....... have problems when they are both running,

As you have mild winters in Britain, heatpumps should work with maximal productivities.
Considered "oversized" at +13C outside (value mentioned by you, I think, not once), I bet you (would) have another point of view about the AC at -13C outside.

P 61. Another worry is how do inverters handle short cycling issues? I know standard fixed speed ones wear out.
In heating the unit cycles on for 6 minutes and then its off for about 20minutes.

I think you are unduly worried about this issue. First, if it is invertor, no problem at all, secondly, agree, we do not change compressors very often at freezers working this way.

P 55. the unit reaches set point very quick but the actual room temp is lower than the unit thinks then due to warm air cycling back into the unit
As the coil's residual warmth keeps warming up the sensor, many here advised You to bring it some meters away. Having it "black-scotched" to an opposite wall - for an experiment - for a week would not give you more inconvenience than struggling with temp-s across the whole place. (then You would have redone it properly, of course).

What is left to do if the control may turn out to be far imperfect, if the position of the units seems to have been a bit better? Probably, experimencing with the sensor(s) and air flows (maybe even blocking air flows - depending on temp-s outside).

Best regards.

THanks for the replys and advice, believe me when I say we have tried everything. The outdoor PCB was replaced, remote sensors were brought in and placed in several places in the room to get better temperature measurement. This improved the temperature at which the unit was cutting out and meant the whole room was equal temperature, however a 1C increase in temperature takes approx 10minutes to register on the digital thermometres and approx the same on the units remote sensors, however this 10minutes the compressor will still run at the same capacity as it did 10minutes ago, it doesnt seem to ramp down.

[Yuri B.]

Outdoor PCB was most probably "unguilty". Its job is to only comply to the orders from the inside init's PCB, so my common sense says.

Did you mean set point achieved, compressor continues to run - always? How you know it runs with the "same capacity"? And what you call "capacity" here?

[Yuri B.]

I am not an expert, does anybody know whether the controls of such systems (with varying refrigerant flow) have the set point offset at the outside ambient temp? My comm sense says they should have.

[back2space]

The compressor was running at the same hertz whether it was 1C off set point or equal to set point. It only seemed to run faster when it was 3C off set point but then only seemed to step the compressor down 1 step despite having plenty of time per 1C increase to adjust the hertz = output.

When set point achieved compressor continued to run which is normal until theres a diff of 1C over the set point at which point it would cycle off. That diff between set point and 1C over the set point the compressor would not change its hertz.

Several engineers checked this over, the last one said it was the O/D PCB that was at fault.

Other engineers checked the compressor by connecting to see what voltage etc it was drawing.

I did not diagnose the PCB fault, but I do know and agree with the engineers that the control strategy is not right at all.

[back2space]

I am not an expert, does anybody know whether the controls of such systems (with varying refrigerant flow) have the set point offset at the outside ambient temp? My comm sense says they should have.

Not sure what you mean? The systems do not compare the outdoor temp to indoor temp to decide the set point indoors.

WHatever the set point on the controller is what the system will aim for inside.

Is this what you mean?

[AbsoluteWDJ]

Well, well, well....Richard....You'll make a good salesman....I'm interested in buying them....You say they've run well through the winter....Is this correct!!!

[back2space]

They have yes, despite the control strategy above as long as you dont need fine control of temps then you would be fine, would suit conservatories or larger heat gain rooms where there is less chance of them needing to cycle off.

Plenty of cool/heat output.

THe only reason selling is because want better temp control from Mitsis which im prepared to pay for.

[Yuri B.]

WHatever the set point on the controller is what the system will aim for inside.

(At last succeded with quoting.) I find it reasonable to suggest that such a (more precise) system should take into calculation the rate at which a conditioned space (might) lose /acquire heat - depending on temp difference between inside and outside - factoring this value into the room control. (But this might be not the case with A/Cs altogether, however, so forget it).

[AbsoluteWDJ]

They have yes, despite the control strategy above as long as you dont need fine control of temps then you would be fine, would suit conservatories or larger heat gain rooms where there is less chance of them needing to cycle off.

Plenty of cool/heat output.

THe only reason selling is because want better temp control from Mitsis which im prepared to pay for.

I'm only pulling your leg my friend....

Peace

[back2space]

I'm only pulling your leg my friend....

Peace

Oh dont lol, ive had so much messing around with this system its unbelievable!

[back2space]

(At last succeded with quoting.) I find it reasonable to suggest that such a (more precise) system should take into calculation the rate at which a conditioned space (might) lose /acquire heat - depending on temp difference between inside and outside - factoring this value into the room control. (But this might be not the case with A/Cs altogether, however, so forget it).

Maybe very expensive systems certainly not LG.

However I know it has a fan control on the outdoor unit but purely for fan speed on o/d unit.

[headgasket]

my dad brought a new fridge once, after two weeks he told me the fridge runs for 10 mins, then off for 6 mins, the point. its only effecting you, you do not have a close control a/c system installed, and you said it is over sized, there you have it i am afraid.a/c works well in a square box, or office, or work shop

[back2space]

my dad brought a new fridge once, after two weeks he told me the fridge runs for 10 mins, then off for 6 mins, the point. its only effecting you, you do not have a close control a/c system installed, and you said it is over sized, there you have it i am afraid.a/c works well in a square box, or office, or work shop

Im not saying its short cycling, it will run for about 20 mins at thermo on, but in that time its not RAMPING DOWN far enough!

The control strategy is poor.