Air Source Heat Pumps

richardc1983

Well it doesnt seem to be drawing any more power, its hooked up to an electric monitoring thing and its drawing about the same before if not slightly less.

Surely if the unit had 2000grm to start with then its got a receiver?

I worked out that on 39metres we should be adding: 330gram.

I thought the correction factor (450) was how many grams were already in it.

This is how he read it also.

When I rang LG tech support they said that the units are not charged to 70metres and they also came out with a similar figure of him to add about 300grams, however I had only estimated the total pipe run.

They said that the 2000gram it quotes in the book is how much refrigerant the system can hold at its max "combined" pipe run of 70mtr.

Not sure where your getting the basecharge from as surely the correction factor is the base charge?

Im confused...

thechippy

Gimme a few mins to double check. I need a glass of wine and a fag........:rotfl:

thechippy

Ok had wine and a smoke.

Pretty sure I'm correct. Yours has a base charge of 2150g @ combined pipe length of 7.5m

Why they use a correction factor I don't know, most don't but I'm sure my calculations are correct.

Yours does not have a reciever, but the unit can still hold the base charge in it's non running pre commissioned state.

If yours is the FM25, I think they are twin compressor as well. One fixed and one inverter!

richardc1983

Ok mate!

its so confusing isnt it, why cant they make things straightforward.

The 2 units that heated fine before seem to be running for longer now rather than reaching set point so quick whilst the other room has reached set point (this was the problem unit if running on its own with the other 2 at thermo off)

AIr off temps of these units dont seem as high but its still maintaining ok and the temp is 23C in my lounge and 22 in the bedrooms.

We would also have the issue of the units that were thermo off would still be blowing warm air as the coil temp would rise sufficienty enough for the cold air prevention to let the fans start, now the fans are not running for as long on units that are thermo off? Not sure if thats a good thing but means we dont get overheating in the other rooms as much.

HMMM????

richardc1983

thechippy wrote: »

Ok had wine and a smoke.

Pretty sure I'm correct. Yours has a base charge of 2150g @ combined pipe length of 7.5m

Why they use a correction factor I don't know, most don't but I'm sure my calculations are correct.

Yours does not have a reciever, but the unit can still hold the base charge in it's non running pre commissioned state.

If yours is the FM25, I think they are twin compressor as well. One fixed and one inverter!

Nope not the new one this is model number FM25AH UE1 which is the first one that only have one compressor.

Check here:

http://mylg.co.uk/data%20for%20site/multi%20f%202008%20outdoor.pdf

Thats the UE3 but its the same underneath as mine.

Gives full tech details too as to what the unit is and refrigerant.

It does quote 2000g but not what your saying.

LG are saying diff so really not sure what there on about.

This is copied from the email from them:

Garry said the following will help you:- 20 gsm per mtr x total liquid line length – 450 gsm correction factor = ammount to add

thechippy

Strange,

If you measure air on and air off the ahu's, as long as the air off is 15c or more than air on, then they are working "ok"

I'm still convinced that the eev's should not be open at all when the system is off.

I know this is a pain, but I really would have the refrigerant charge weighed out, so we can check the system has the correct charge. This is fundemental to the operation and we can't delve into other areas until this is sorted....;)

richardc1983

The EEVS are open on all units in heating mode 10% that are either thermo off or switched off as long as one other unit is turned on.

Seriously though i had a document somewhere that showed the reason for the eevs being slightly open.

A few people have advised this is normal also.

I think perhaps at the mo should see how it runs and stuff if we are struggling to heat or cool then we need to look at other steps dont we.

Its certainly keeping the place warm tonight.

Just done its first defrost of the night since 7pm.

thechippy

Ok mate,

See how it runs for a bit, but if not happy get the charge pulled and weighed to determine if it's correct.

See if you can find the documentation re the eev's, as at first thought (to me) it seems to serve little purpose.

richardc1983

its something to do with allowing oil return to the compressor they said.

Im just measuring air off temp on one of the units thats demanding heat will let it run for a 10 minutes and see what it is and report back.

Keep tuned for the next update!

richardc1983

On the other forums, someone also mentioned that if its undercharged cycles will be shorter:

"Over charge over works the compressor and shortens life time, under charge system cycles are shorter over working thermistat contacts and stressing compressor yet again shortening its life."

Does this mean air off temps would have been higher meaning the unit was reaching set points quicker and cycling off.

Seems to be running a lot longer now and comfort is better as its not cycling off and the room temp aint dropping off as much.