LG heat pump problem

[back2space]

When the compressor ramps down does the EEV valve also close down a few steps also???

[Thermatech]

For the last year or two LG have been providing training for air conditioning engineers in the UK at a new training centre.
Some engineers have been & then posted comments on this forum about it.

So here we are 99 posts on this thread & not one single post from any a/c engineer who is prepaired to try & defend the product.

Yet we know that some of the 25000 members have been to LG training.
We know that some who post on this forum carry out installation & service of LG split systems.

Listen to the sound of silence
it tells a story.

[nike123]

When the compressor ramps down does the EEV valve also close down a few steps also???

Jes! .......

The expansion valve is controlled as a function of the speed of the compressor as the compressor speeds up then the expansion valve opens.

[back2space]

I hope you guys are not getting fed up with me. Its a shame that the guys who install this kit are not speaking? Either they dont know how it works properly or as you say Thermatech, the sound of silence paints a picture!

[nike123]

I do feel that it is working better today though its 2C outside and the unit is only cycling off once every hour (twice max) as apposed to every 10minutes.

As I already said here, that is probably because this units are to big for your heat loss.

[back2space]

So I think its going to cost me less to run it when its cold as its going to stay on for longer but ramped down as it should. Whereas when it cycles back on again and theres a 1c difference it runs at full pelt to get to the setpoint.

[nike123]

I hope you guys are not getting fed up with me.

Not at all, for me. In fact, what could service engineer could do when is not on work, except talk about work or beer or girls. Since there is not much active girls here, and Frank keeps his beer wisdom for himself, only what is left is to talk about work.

Its a shame that the guys who install this kit are not speaking? Either they dont know how it works properly or as you say Thermatech, the sound of silence paints a picture!

You are maybe expecting to much from installers. They dont need to know all details to be able to install AC-s.
Details are only required for service engineers and technical support personnel.

[back2space]

What do they teach you on the LG training though? The operation of the system or just how to install it?

[back2space]

Were just deciding what to do tonight... thinking were going to have a party tonight so we will end up having it in cooling mode!

[nike123]

So I think its going to cost me less to run it when its cold as its going to stay on for longer but ramped down as it should. Whereas when it cycles back on again and theres a 1c difference it runs at full pelt to get to the setpoint.

Nope.
If it is cold, then your space heat loss is higher and that mean that totally produced heat (for keeping indoor temperature at set point) from AC is going to be higher and therefore costs will be also higher.
It is not your AC who consumes energy, it is your space who do that and AC could produce that energy with higher or lower efficiency.
Highest power consumption is when outdoor temperature is lowest (low COP) and AC still produces enough heat to maintain set point. Lowest consumption is when outdoor temperature is high enough that COP is highest and heat loss of space is lowest.

You could compare that with barrel of water with opening of x cm at bottom, filled with buckets of water
Water leaks constantly and you need to fill it with certain tempo to replenish spilled water. If you have too big bucket you will need to fill it rarely. If you have small bucket you will need to fill it more often or without pauses at all. If opening is big enough you cannot replenish water even with big bucket.
But amount of replenished water will be always same as leaked water as long as you could keep up with leaks.
Now imagine that level of water is set temperature and
fluctuations of level of water between two bucket pouring are your variations in return temperature.
Also imagine that bottom opening is heat loss of space.
Now play little in your head with variating these tings in analogy with your AC and you should have pretty plastic picture what is happening there.

If you replace bucket (as on-of compressor analogy) with hose from water supply with valve with 4 flow rates and closed position you are now have analogy for your inverter compressor.

[back2space]

Yes I understand that analogy. Surely though that when the ac isnt cycling and is happy maintainging setpoint at lower compressor Hertz the energy meter shows lower power consumption. But when its constantly cycling and starting up at 100% this is usnign more energy. I was told by installer that inverter ramping down avoids the cycling issues cos it operates slower thus stopping it having to operate at 100% to regain the temp.

I understand the heat loss, but Ive also found leeaving the system on all night but at a lower temp means it works less harder to regain the setpoint when i increase it again.

[nike123]

What do they teach you on the LG training though? The operation of the system or just how to install it?

I suppose that installers learns how to install properly, and service engineers learns how units works and how to diagnose and service them.

That is why on larger systems, after instalation work is done, startup usually makes service engineer to establish that everything works as it should be.

[Thermatech]

B2S

I would encourage you to look at the Eurovent web site & check the energy rating for the system combination you have.

There is listed an FM25AH UE1 with 2 MS12AH N50 indoor units.
Not exactly the same as your combination but look at the ratings.

Heating COP = D rating
Cooling EER = B rating

This tells us that the system is better at cooling efficiency than heating.
But also tells us that its not very good efficiency in heating or cooling as the best rating is AA & some other more expensive cost manufactures have AA ratings for most multi split combinations.

The system would seem to be optimized for cooling performance not heating performance.

The standard test conditions for Eurovent is for max load & even at that the system performance is not so good.
The performance at low load is not tested & so if the system is not optimized for low load performance by factory design engineers then that does not affect the energy rating.

[back2space]

OK thermatech Have you a link to these statistics, i will make my way over.

[Thermatech]

The system performance evaluation procedure which you are carrying out on this system does confirm some things which some of us have come to expect from experiance of trouble shooting split / multi split / VRF systems.

1/ Just because it has the word INVERTER on the box does not mean that the system has excellent efficiency. That all depends on the control stratagy & how well the manufacturer has optamised the system control stratagy for high & low load operating conditions.

2/ Just because the outdoor unit has an energy lable on it that does not mean that the system will be energy efficient in all operating conditions.

3/ You get what you pay for.
The premium brands cost more but have much better control stratagy programed into the more expensive chips on the more expensive circuit boards which take much more R&D to develop.

[back2space]

I guess I know for next time dont I know. Either way ive got a better system than a standard on off compressor. Plus im getting a lot more better value heating and more for my money than using electric fan heaters.

To be fair the A/C system with only one unit on heats the entire flat. So it has no probs outputting heat even in cold weather!

[Thermatech]

www.eurovent-certification.com

[Gary]

I guess my perspective is a little different than some. As a service tech it is not my job to select the equipment. It is my job to make the existing system perform to the best of its abilities.

With this in mind, I find a comparison of different brands/ratings... uninteresting.

I was hoping that someone would jump in here with a definitive description of what this system is supposed to do so we could learn something, but apparently that just isn't happening.

[nike123]

I was hoping that someone would jump in here with a definitive description of what this system is supposed to do so we could learn something, but apparently that just isn't happening.

I think that posted document explains control strategy prety much transparently except part of how exactly looks calculation of outdoor unit capacity in relation to indoors required capacity, and how is EEV steps related to that. Rest of control process is pretty much clear.

[nike123]

I guess I know for next time dont I know. Either way ive got a better system than a standard on off compressor.

I would not say that is generally always the case or even in your case, maybe.

[back2space]

I would not say that is generally always a case.

Why is this?

[nike123]

Why is this?

Because only thing what is matter is is how comfortable you are, and on what efficiency that comfort is delivered. If you don't feel any difference in comfort with on-off system and that on-off system deliver heat more efficiently, than you could say that there is not necessary inverter system better than on-off system. Especially when its poor control nulls its gain in performance on other points.

[nike123]

But when its constantly cycling and starting up at 100% this is usnign more energy. I was told by installer that inverter ramping down avoids the cycling issues cos it operates slower thus stopping it having to operate at 100% to regain the temp.

From power consumption stand point, it doesn't matter if 2kWh are consumed in intervals or as steady or varying current draw.
It is same 2kWh of power consumed.
However, it is important at what COP is outdoor heat transfered to heated space.

Only real comparison in real life conditions could tell you if your inverter system is more efficient and comfortable than on-off system.
That real comparison is when you, in two identical places, put two different systems at identical conditions for one season and then compare total power consumption of each and feel of comfort.
I personally don't like feeling when indoor unit of inverter is at minimum.
From what I know, there is no such comparisons documented.

[Gary]

I think that posted document explains control strategy prety much transparently except part of how exactly looks calculation of outdoor unit capacity in relation to indoors required capacity, and how is EEV steps related to that. Rest of control process is pretty much clear.

I found it fairly ambiguous and confusing.

In particular, the specs are for a dual compressor system. Having one compressor changes things.

As to the min/nominal/max ratings: No two systems are truly identical. I would assume that a number of systems were tested under tightly controlled conditions and some performed at min while others performed at max, the nominal rating being the average performance. Therefore, given the specified conditions, anywhere in that range should be considered normal... but then, this assumes a dual compressor system, for which we do not have the specs.

[nike123]

I found it fairly ambiguous and confusing.

In particular, the specs are for a dual compressor system. Having one compressor changes things.

As to the min/nominal/max ratings: No two systems are truly identical. I would assume that a number of systems were tested under tightly controlled conditions and some performed at min while others performed at max, the nominal rating being the average performance. Therefore, given the specified conditions, anywhere in that range should be considered normal... but then, this assumes a dual compressor system, for which we do not have the specs.

I would say that spec are for that particular AC, as you could see from model# on header of specifications.
Also, I would say that description of control logic is maybe not for this particular model and I would love to see this model service manual for that reason.

Regarding min/nominal/max ratings: Maximum rating is when compressor speed is highest at that particular temperatures of return air and outdoor air, and that is usually "120-130%" of nominal capacity. That speed compressor could hold only relatively short time period, when there is need for capacity high, like after power up.
Then, min rating is when compressor is on his last power step before shut down (and at same return and outdoor temperature as above) , and that is usually around 30-40% of nominal capacity.


Nominal capacity is "100%" capacity.

[back2space]

I found it fairly ambiguous and confusing.

In particular, the specs are for a dual compressor system. Having one compressor changes things.

As to the min/nominal/max ratings: No two systems are truly identical. I would assume that a number of systems were tested under tightly controlled conditions and some performed at min while others performed at max, the nominal rating being the average performance. Therefore, given the specified conditions, anywhere in that range should be considered normal... but then, this assumes a dual compressor system, for which we do not have the specs.

Gary page 210 of http://mylg.co.uk/data%20for%20site/...%20outdoor.pdf shows that the FM25AH UE3 has just the inverter compressor. My model is the UE1 version, which also has just the inverter compressor. Mine is the European Model however the specs book doesnt show the UE1 so I have been told to go by the UE3 specs which is the same as mine apart from a few cosmetic changes.

So gary the specs on page 218 are indeed for one inverter compressor. Can you eleborate on this now?

[back2space]

Regarding min/nominal/max ratings: Maximum rating is when compressor speed is highest at that particular temperatures of return air and outdoor air, and that is usually "120-130%" of nominal capacity. That speed compressor could hold only relatively short time period, when there is need for capacity high, like after power up.
Then, min rating is when compressor is on his last power step before shut down (and at same return and outdoor temperature as above) , and that is usually around 30-40% of nominal capacity.


Nominal capacity is "100%" capacity.

Ok so its never reaching the last step down it prefers to shut off totally so I thought that it wasnt reaching this because the outoor ambient wasnt high enough. I thought that the min, rated & max were based on a max for the highest comp output in very cold weather and the rated is what the indoor and outdoor temps were based on

[back2space]

Right guys, despite the problems and confusion above the outdoor temp ambient has been hovering at 0.2 and is now -0.5 now. I got in the flat at 3pm and the indoor temp was 10C!!! It was cold!

[back2space]

UPDATE:

Remote sensors arrived today, what a mess around trying to fit them as the plugs on the end that connects to the board are designed for cassette/ducted unit. SO had to take the plugs off and fit to the existing return air plug.

Have mounted them at 1.5mtr from the floor on a wall where warm air flow from the unit will not affect it.

Couple of things: The lounge sensor had to move several times as it appeared that the sensor was being affected by the temperature of the outside wall which is very cold to the touch, this was making the outdoor unit run at full speed However moving it so it wasnt touching an outside wall means that temperature control in this room is no longer an issue.

2nd point is on the bedroom unit... now seems to be the problem unit. Have mounted it on a non external wall however (but fitted on wall opposite the external wall) temperature control in this room is even worse now. Before warm air was cycling back to the unit and shutting off too soon but now the temperature is way overshooting the set point temperature. For instance set point of 19C the room temp reaches 22C before shutting off. If I try to compensate by putting down to 18C doesnt make any difference unit still seems to be a couple of degrees over. Tried connecting the old temp sensor to the end of the new long cable and same results. COuld the wire be damaged or something? I have measured temps with an accurate digital thermometer right next to the remote sensor, is it still sensing wall temperature despite not being on an external wall? I dont understand as the digital thermometer is small yet manages to pick up the air temp being 22C when 19C is wanted. I appreciate a 1C differential either side of set point but not 3C.

MODS: Any chance of moving this to the Main Air Con forum and out of Heat pumps as I feel will get more attention and if possible could post be renamed to LG Air Con Problem as I did not start the original post someone did it for me.

Thanking you all.

[Brian_UK]

I think that it has been receiving enough attention not to need moving and as it is about a heat pump seems to be in the right place.

[back2space]

Sensors arrived,

After being quoted £40 by several distributers for each sensor I ended up dealing with LG comfort cooling who have been helpful from the start to finish they quoted £18 per sensor... much more reasonable!

After receiving these and arranging for them to be fitted, they didnt fit, wasnt just simple unplug existing sensor! had to remove the plug at the end and mess around with existing plug to get it fitted as the plug was too big on sensor. But then this didnt work so have had to just extend the existing sensor using the cable provided with the remote sensor. So I have paid for a posh box and cable for nothing really.

[nike123]

Sensors arrived,

After being quoted £40 by several distributers for each sensor I ended up dealing with LG comfort cooling who have been helpful from the start to finish they quoted £18 per sensor... much more reasonable!

After receiving these and arranging for them to be fitted, they didnt fit, wasnt just simple unplug existing sensor! had to remove the plug at the end and mess around with existing plug to get it fitted as the plug was too big on sensor. But then this didnt work so have had to just extend the existing sensor using the cable provided with the remote sensor. So I have paid for a posh box and cable for nothing really.

If you listened my advice than you will be now richer for that 36 pounds and you will be having hot home from day one of your posting! Don't forget, this is first response on your problem.
http://www.refrigeration-engineer.co...51&postcount=2

Sorry, but I just cannot resit to tell you "I told you so!".

[back2space]

Yes nike but I paid £18 per sensor from LG comfort cooling not the quoted £40 from other installers.

So I have done ok. An electrician would have charged same ammount. Plus electrician would have had to mess with the control board to get it wired in.

Sensors now put 1.5metres above floor level.