Multisplit fault

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UPDATE:

Email received from installing contractor last week 21st March saying he was going to speak to LG and ring me back on the 23rd with update.

Still nothing from him but have heard from Graham Hendra via email on Thurs 26th who advised the following:

Today I spoke with the installing contractor

He will be in contact about your machine together some resolution will be found

regards

Graham Hendra
General Manager Airconditioning LGEUK

Still waiting to hear from the installer yet though.

[Mr Memory]

Has been fine all day then when I go back in the bedroom tonight room temp is 23C and fan is just constantly blowing luke warm air. Set point is 20C.

Living room unit is at 20C and seems to be struggling to heat.

Notice hendrag hasnt been in touch again and also I have emailed LG and no response from them!

WIsh I had never got this equipment a bloody fan heater would have been better control

As Frank mentioned, quit slagging off manufacturers and maybe someone will want to help you.

Firstly in your OP you provided not one model number! If you try to contact LG (or one of their distributors), you will be required to provided this as a minimum, or it is unlikely that you will get any help.

LG make very good equipment now (compared to the bad old days), and any AC system can and will need some sort of attention during it's lifetime!

Try e-mailing your question (WITH model numbers) to airconhelpuk@lge.com or call their technical helpline, and they WILL help you out - don't be telling anyone otherwise, because it is simply not true!

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As Frank mentioned, quit slagging off manufacturers and maybe someone will want to help you.

Firstly in your OP you provided not one model number! If you try to contact LG (or one of their distributors), you will be required to provided this as a minimum, or it is unlikely that you will get any help.

LG make very good equipment now (compared to the bad old days), and any AC system can and will need some sort of attention during it's lifetime!

Try e-mailing your question (WITH model numbers) to airconhelpuk@lge.com or call their technical helpline, and they WILL help you out - don't be telling anyone otherwise, because it is simply not true!

Revival of old post or what... feb 09!

yes no model numbers were given but anyone who looks at my postings or regular on the forums will probably know the model numbers.

Emailing LG... done this many times, over many different problems... (currently failing to start when the timer is used) but no resolution in place... just passed back to the installer (who now is bankrupt and no longer in business but apparently owes lots of monies!)

I would say a single lg split might be ok, but a multisplit is just asking too much for the lg equipment to work... control strategy is shoddy and all over the place.

Because I have spent a small fortune on engineer visits all agreeing it is not operating properly lg still dont want to know.

I since email them myself now as cannot afford any more call outs!

The point about slagging off manufacturers. Im sure you would be doing the same if your new plasma tv wasnt working and u was getting no where with customer services etc. Its freedom of speech and the view of most engineers is that LG is cheap tat and they would avoid.

My experience probably just backs that up. If LG wants a good reputation then they need to build on that and sort the issues out with their equipment.

[cadillackid]

back2space: if you are still having these issues with your system you might look into seeing if LG will replace the PCB's in that system for you..

that Multi-split had not been out for a real long time when you purchased it.. they have likely since upgraded the software in the indoor and outdoor boards and that may just fix the issue..

since you are in a facilities helpdesk i think you are more than qualified to R&R the PCB's in the outdoor and indoor units...

the other thing that crossed my mind is that the LEV for the bedroom unit could possibly be bad.. causing an invalid position signal sent back to the PCB.. basically the vale would report its open at 10% when the physicval valve might be at say 20%.. allowing more refrigerant flow through the bedroom unit.. and either warming the coil up too much or causing condensation in the liquid line which might cauyse a warmer than normal liquid line reported back to the main PCB telling the system to ramp down on the compressor....

I know this an old post but it sounds like the issue was never resolved...

the other thing I find with many of the chinese made multi-splits is that the outdoor unit does not have the capacity to handle all of the indoor units operating at the same time..

to avoid excessive defrost calls or the possibility of condensed refrigerant in the outdoor coil during cold outside temps these units will ramp down the compressor even when multiple indoor units are calling.. this is done to keep the outdoor coil temperature up a bit..

in my opinion thats not right.. if I buy a 12+12 system I should be able to run both indoor units and expect the outdoor to run flat out but many do not have the outdoor coil area to support both indoor units in heat esp at lower ambient temperatures...

-Christopher

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back2space: if you are still having these issues with your system you might look into seeing if LG will replace the PCB's in that system for you..

that Multi-split had not been out for a real long time when you purchased it.. they have likely since upgraded the software in the indoor and outdoor boards and that may just fix the issue..

since you are in a facilities helpdesk i think you are more than qualified to R&R the PCB's in the outdoor and indoor units...

the other thing that crossed my mind is that the LEV for the bedroom unit could possibly be bad.. causing an invalid position signal sent back to the PCB.. basically the vale would report its open at 10% when the physicval valve might be at say 20%.. allowing more refrigerant flow through the bedroom unit.. and either warming the coil up too much or causing condensation in the liquid line which might cauyse a warmer than normal liquid line reported back to the main PCB telling the system to ramp down on the compressor....

I know this an old post but it sounds like the issue was never resolved...

the other thing I find with many of the chinese made multi-splits is that the outdoor unit does not have the capacity to handle all of the indoor units operating at the same time..

to avoid excessive defrost calls or the possibility of condensed refrigerant in the outdoor coil during cold outside temps these units will ramp down the compressor even when multiple indoor units are calling.. this is done to keep the outdoor coil temperature up a bit..

in my opinion thats not right.. if I buy a 12+12 system I should be able to run both indoor units and expect the outdoor to run flat out but many do not have the outdoor coil area to support both indoor units in heat esp at lower ambient temperatures...

-Christopher

Hi Christopher

The indoor units are MV12AH x 2 and the outdoor is an FM25AH. So perfectly matched with both units running.

If only one indoor is calling for heat then full output should be achieved by that unit that is switched on. Instead it drops off unless both indoors are calling for heat we then see good output with air offs off 45C or so.

The issue was never resolved... about a year ago the outdoor PCB was replaced with a new one, this never corrected the issue and it still behaved the same.

You mention the issue of the LEV on the bedroom unit. We observed the same issues if it was the lounge unit at thermostat off and the bedroom unit calling for heat. It does exactly the same, so it could be coincidence that both LEV's are bad? I think not... read on lol...

In October 09, we had a 3rd unit fitted onto the outdoor... a wall mounted unit for our spare bedroom which we rent out. This is also a 3.5kw unit... so of course I understand that if all 3 units are calling for heat this then puts the total of indoor units over capacity for the size of the outdoor unit... and thus it shares its capacity out across all three.

However when all three are calling for heat we get fantastic air off of about 42-44C, if 2 are calling for heat, again good air offs, if only 1 is calling for heat (the new wall mount in the back room) we get air off of 32C. This is if the other two are switched on but at thermo off. In summary when all indoors are calling for heat they work great when only one is, performance is terrible.

Switch all other units off and leave the wall mount on... air off 44C within 5minutes and compressor ramped up further than it would if the other 2 were left on at thermo off. When units are physically switched off I do believe the EEV's shut down to 10% as the coils go noticeably cooler, however they dont seem to follow suite at thermo off.

The wall mount also will not go onto high fan speed, unless the other 2 units are turned off or at least one is calling for heat as the coil never gets above 38C.

Pipe and coil sensors were replaced on the indoor to see if the coil sensors were at fault... they were fine but unit will still not go onto high fan speed under the above conditions... this results in a room that never gets warm because we cant increase fan speed unless the other units are turned off.

So it seems that too much refrigerant is sent to the units that are at thermo off when this refrigerant should be going to the unit that is calling for heat.

So yes to me the eev stays open the same % on all units that are turned on whether at thermo on or thermo off as when the fan comes on periodically to clear the heat build up the air off is the same as on the unit that is thermo on 32/33C.

LG state that it should be 10% on units that are thermo off/off state, however I think if they are turned on or thermo off they remain open the same value they were when they were thermo on/calling for heat. (they dont close down)

Meaning outdoor unit is ramped down to match the load conditions on the system (1 unit operating) but the eev positions do not match.

Obviously I have put a lot of thought into this, a lot of engineer visits who agree, 1 member off the forum visited also. Yet LG still dont want to listen... and try pushing it back onto the installer or the engineer.

As I say the PCB was replaced early last year, the system was installed the year before that so unless they have changed the software on the PCBS since I suspect that things will still be the same.

Really not sure what to do next... you guys agree it isnt controlling right... we all do in fact yet trying to get LG to listen without kicking off is another thing.

I agree LG should be coming out to look at this problem but £300 for an engineer visit and they may just say... its how it was designed to work... im then out of pocket.

There are different versions of this outdoor unit. Mine is the FM25AH UE1 there are version that go upto UE3. If I was to get a UE3 PCB I dont know if the software would be any different or whether it would even work.

There is even a long pipe mode setting which LG advised to switch on yet this does absolutly nothing, engineers have said the pressures dont even increase and the compressor does not step up when this mode is turned on? LG say it increases the frequency for longer pipework which my wall mount is on.

By all means if someone wants to come visit or try to take this up with LG then it would be much appreciated. LG view me as not being an engineer and will not entertain me. Engineers who visit, do not rate LG so when they speak to them they just feel fobbed off by LG.

All in all a pile of $hite! With no ends of problems. The multisplit method is best for me due to outside space and living in a flat etc but NOT LG's multisplit!!! They dont work very well at all.

I await your comments...

Regards
Richard.

[cadillackid]

I totally agree that this is a controls issue.. esp since you can demonstrate that an indoor unit turned completely off does allow the EEV to close correctly... my guess is LG must have some sort of "hot keepalive" feature and that is why the valve stays open more than 10% for units in a thermo-off state....

like others have said 10% is normal for oil return on these... (why they dont just do a periodic oil return cycle I dont know)..

trouble is im across the pond in the USA so im not going to be of much help in this regard....

sure seems to me this is not the way a system would be designed to operate.. in fact the CHigo based multis I have worked on were the opposite of yours.. when all the indoors were calling the system would give mediocre air-off temps....

in your case my guess is that they only allow a certain compressor frequency for a single indoor unit.. not the way I would run a control.. as personally if it were my design I would allow the compressor to run as much as it needed for a single indoor unit to maintain the desired middle pipe temperature on the indoor coil...

when you have just one indoor unit running what is the difference in temp from inlet to outlet (suction to liquid) on the indoor unit?

trouble is if we are fighting a controls issue the only way to fix that is different software.. and I have yet on any of these LG or chigo units to be able to kipe the software from the micro in such a way that I could edit it and burn it back in....and trust me Ive tried as I really hate the control algorithms used on many of these.....

-Christopher

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I totally agree that this is a controls issue.. esp since you can demonstrate that an indoor unit turned completely off does allow the EEV to close correctly... my guess is LG must have some sort of "hot keepalive" feature and that is why the valve stays open more than 10% for units in a thermo-off state....

like others have said 10% is normal for oil return on these... (why they dont just do a periodic oil return cycle I dont know)..

trouble is im across the pond in the USA so im not going to be of much help in this regard....

sure seems to me this is not the way a system would be designed to operate.. in fact the CHigo based multis I have worked on were the opposite of yours.. when all the indoors were calling the system would give mediocre air-off temps....

in your case my guess is that they only allow a certain compressor frequency for a single indoor unit.. not the way I would run a control.. as personally if it were my design I would allow the compressor to run as much as it needed for a single indoor unit to maintain the desired middle pipe temperature on the indoor coil...

when you have just one indoor unit running what is the difference in temp from inlet to outlet (suction to liquid) on the indoor unit?

trouble is if we are fighting a controls issue the only way to fix that is different software.. and I have yet on any of these LG or chigo units to be able to kipe the software from the micro in such a way that I could edit it and burn it back in....and trust me Ive tried as I really hate the control algorithms used on many of these.....

-Christopher

Hi Chris

Thanks for your response. The unit also does an oil return cycle every five hours in heating mode, (reverse cycle with compressor at full pelt) for 5 minutes then reverts back to heating.

Not sure of the difference in temperature from inlet to outlet but engineers have assured me it is in range.

The inlet temp is usually the same as those at thermo on as those that are thermo off. But units that are physically off have a lower inlet temp... or whichever way you look at it.

[lomb]

Ive gone for 6 single MHI splits to heat and cool a building with 6 condensors outside (probably a seventh soon). From everything from compressor burnout taking out all the indoor units and pipework to leaks , oil return, control, fault finding, expense with downtime if anything goes wrong i chose this option and im glad i did.
Bsck2Space could you not have just stacked the oudoor units one on top of another? There is generally plenty of space on buildings if gets over the boxy look of the machines and they dont actually look too bad kind of cool actually!

[back2space]

Ive gone for 6 single MHI splits to heat and cool a building with 6 condensors outside (probably a seventh soon). From everything from compressor burnout taking out all the indoor units and pipework to leaks , oil return, control, fault finding, expense with downtime if anything goes wrong i chose this option and im glad i did.
Bsck2Space could you not have just stacked the oudoor units one on top of another? There is generally plenty of space on buildings if gets over the boxy look of the machines and they dont actually look too bad kind of cool actually!

Yeh that could have been an option and yes I would have had better control of the system but the whole thing was done on a budget so installation costs would have been higher if I had gone for 3 separate units.

The system has never broken down touch wood its just the control strategy that seems to be so poor.

Have you any pictures of your installation?

[cadillackid]

I also have installed multiple units.. I originally thought of a multi-split but had also didnt want to lose the whole system if i had issues.. (and i have had issues).. plus in effect i can ramp my house all the way from 5000 BTU all the way up to 51,000 BTU... (on a humid day)... so i can have my quick cool downs AND still keep control of the humidity....

I know ive shown pics of the indoor installs as i was prototyping out my system but i can post a pic of my outdoor units if you like....

of course in my case since I customized the indoor system and have it all integrated into my basement and through the ducts i do not even have the "wall warts" on the inside of the house and no "linehide" going up the outside walls for the high wall mount units...

I know in europe its unusual to have ducted air systems in homes and is normal for people to have splits on the walls.. but it hasnt quite caught on in the USA yet as many people here seem to consider wall mounts or cassettes as "ugly"...

my guess is also that running a Multi-split may be more economical on the budget as each inverter does have some Loss in it so perhaps running 1 compressor might be better than running 3 or 4 even at low speed.. albeit my compressors rarely ever ramp up very high... although yesterday was an exception... it was 86 outside and the dewpoint was 73.. the house was open windows all day and then i got warm and decided to run the air-cond.. for a short while i could hear all 3 compressors whirring away unti it started to bring down the indoor temp and humidity...

I honestly think it is a design fault on the part of LG as it seems all of the OP's hardware is functioning properly.. or it may be an unforeseen fault in the way oil returns to the compressor so they leave the EEV open to keep a flow going...

one of the things im finding out about all of these chinese units is that the manufacturer in china does not typically also make their board-sets.. it is out-sourced... and to keep the costs down low they order thousands and thousands of board-sets from the board-house..

so if there is a software change mid-stream they do not stop the lines, update the software and go, they run out current stock on boards and then go...

they are also very aware of the volatility of the situation as well... say a board house named "FTL" sells 50 thousand boards to Chigo who makes splits for 15 different name plates... first the customers begin complaining to their installer that a unit is wacky... the installer calls the brand name (not chigo).. the brand name tries to shoot the trouble and cant nail it, send new boards, replace parts, etc... finally they contact Chigo about the issue.. the barrier of western-world to china is a bit tough to deal with...

langauge barriers.. an overall fact that china doesnt hold quality to as high standards as western world...

Chigo is not likely going to ever admit that there is a design flaw in their software... why?? because they produce these things so cheaply already there is no $$ left in the deal to open up the flood-gates to all kinds of people that want new board-sets for free.. so they quietly nudge the board maker.. the changes are made, the issue fixed in future production....

my point by thius long boring post?? unloess its a huge MAJOR flaw that makes the unit fail to operate or allows springs and spragues to fly.. you will likely never hear about the fix and it takes a LONG time to make it into the stream.. and thats only if they get enough complaints to warrant getting the board-house to make changes...

that said.. I *am* finding that china is not very good with their software security and that they leave the JTAG port on their ATMEL micros Wide open so chances are the code could be disassembled, reverse engineered and the issue fixed... but I dont guess you or anyone else on this board would want to buy me a unit and then pay my hourly rate to reverse engineer and fix the code... by that time you could fit a mitsi...

-Christopher

[lomb]

Yeh that could have been an option and yes I would have had better control of the system but the whole thing was done on a budget so installation costs would have been higher if I had gone for 3 separate units.

The system has never broken down touch wood its just the control strategy that seems to be so poor.

Have you any pictures of your installation?

Sure, il post when i get a chance. To be honest i think installers prefer multisplits as thats what customers demand and they demand that becase they dont know better and want as few condensers as possible. Efficency wise ive worked out the single splits are cheaper to run. Even vrf units arent as efficient as single splits except when all internal units are running which is rare in the real world. Part of the reason is the compressor is oversized for full load and is thus operating less efficently at part load. Just look at the COPs and how they go down when less internal units are connected(or switched on!)

[back2space]

Efficency wise ive worked out the single splits are cheaper to run. Even vrf units arent as efficient as single splits except when all internal units are running which is rare in the real world. Part of the reason is the compressor is oversized for full load and is thus operating less efficently at part load. Just look at the COPs and how they go down when less internal units are connected(or switched on!)

Really... when I did my sums I worked out that if only one indoor was operating then separate splits was cheaper to run but as soon as you run more than one indoor unit the multi then becomes the more efficient.

As there are certain margin's that each units can ramp down/up to.

If the multi is ramped right down and all indoors are running at minimum duty then you will save more with the multi as you are only running one compressor but if your only running one indoor and the outdoor is ramped right down the larger compressor cannot ramp down as far as a single 1-1 split.

For me separate splits would probably have been the better option as very often I only have one indoor running. Only in the depth of winter do all 3 indoors run at the same time or in the state of thermostat on.

[cadillackid]

here is how I have my units set up outside the back of my house.. they look closer to the house in the pics than they really are.. the spec in the docs for them was 8".. I have them 20" from the back of the house and have killed all the vegetation behind them.. there is plenty of room to work on them...

one of the things I would say against stacking them, is that to service them you usually have to remover the top panel before you can take the front or back off.. and also the electrical box inside often as screws on top that need removed to access the circuit boards...

-Christopher

[lomb]

Really... when I did my sums I worked out that if only one indoor was operating then separate splits was cheaper to run but as soon as you run more than one indoor unit the multi then becomes the more efficient.

As there are certain margin's that each units can ramp down/up to.

If the multi is ramped right down and all indoors are running at minimum duty then you will save more with the multi as you are only running one compressor but if your only running one indoor and the outdoor is ramped right down the larger compressor cannot ramp down as far as a single 1-1 split.

For me separate splits would probably have been the better option as very often I only have one indoor running. Only in the depth of winter do all 3 indoors run at the same time or in the state of thermostat on.

exactly.. but my figures show that if one has a four unit split then the efficency is low even if three internals are running. single splits are definately more efficent than the best VRF systems never mind the day to day multisplits. Also take into account that unless one has a true vrf then one cant heat and cool in seperate rooms at the same time.
Here are some links to COPS on multis as an example
http://www.airconwarehouse.com/acata...-Multizone.pdf
page 30ish. Additionally note hitachis basic single split gives a cop of nearly 4. I remember looking at a daikin multi 5MXS90E and the difference was even more stark.What was A efficency with all the inners running turned out to be D or E with 1 connected .

[lomb]

The only efficency disadvantage of seperate splits is the standby current and crankcase heaters but this is only about 50 or so quid a year versus say 20 with 2 multis on 6 splits a small price to pay for the advantages.

[cadillackid]

I also like having multiple units because of the true 'variable speed" i can get in my house... in the setup I showed above.. I have 5000 BTU all the way to 51,000 BTU at my disposal all inclusive...

oh and the fact if one dies my whole house is not down.. i still have 2 others that can really make up the difference... with my systems being centrally ducted I can tell the computer to re-direct the electronic dampers such that it pushes conditioned air from one room to the other in the event of a failure....

the only thing I cannot d is close the supply damper of an operating unit.. thats a very bad thing....
-Christopher

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sorry ive ben a bit busy, changed my name im no longer hendrag but still doing the blogs

hope you like em

graham

Hope we like what? LG no!

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I know this is an old post but just to highlight how long these problems have been going on for as I am sending an email to LG requesting that they send one of their engineers.

I cant believe this has gone on for nearlly 3 yrs.