mini splits how to check charge level?

[capthummel]

I have a LG mini split freezing up on the inside unit and the high side valve on the outside unit. Also not cooling up to par. LG told me their is no way to tell charge level. Is their any way to tell from the access port on the low side at all?

[cadillackid]

im finding with minisplits the BEST way is to evacuate completely and recharge by weight esp if its an inverter... SOME inverter units have a diagnostic mode where it will force the compressor to max and the EEV to Max and you can use standard charging practices and get close.... but if its a 410a unit I would recover, evacuate and recharge with a scale....
-Christopher

[Thermatech]

The best method is recover , vac & recharge by weight.

On some split systems there is a discharge service port so you can monitor discharge pressure.
In this case you can run the system in test mode & monitor the discharge pressure & discharge temperature with electronic temperature meter.
This will give you the 'discharge super heat'
Generally I find on R410a that if the DSH is over 45 deg C then that is good indication of SOG.
You can also take suction pressure , suction SH & compressor shell temp.
If the suction pressure is lower than you would normally expect but the SSH & compressor shell temp is higher than you would normally expect then that would also be an indication of SOG.

However all these readings can also indicate SOG if there is a slight blockage at some location in the system although the system is found to have a correct charge.

As LG make budget cost systems many features you would normally expect to find on a split system have been removed to make it as cheap as possible.
So while more expensive split systems are precharged for extended interconnect pipe lenght & have a large suction accumulator which tends to make the system less charge critical for LG the suction accumulator may not exist or is very small to save cost.
This make the LG split systems much more charge critical than many other split systems & just a few hundred grams can have an impact on cooling performance so geat care needs to be taken when charging the correct weight of charge.

[Thermatech]

If the system is running in cooling & the HP service valve at the outdoor unit is frosted then that might indicate poor refrigerant flow through the outdoor unit expansion device.
The HP liquid is usually pre expanded at the outdoor unit on this type of split system so would expect cold HP service valve but not frosted & this could indicate a blockage or incorrect operation of any electronic expansion valve if one is fitted.
This would then make the system look SOG as the refrigerant could be backed up in the outdoor condenser coil.

[cadillackid]

gotta Love the lower cost units.. the Grunaire units are sold from several internet outlets with a 25 foot lineset - yet the manufacturer from china (Chigo) has repeatedly told me in emails that the units are shipped for a charge of 15 feet of Lineset...

that in and of itself sets up installers for failure.. however the real story is that the manufacturer isnt real careful about how much charge they put in the unit so often the units will seemingly run fine when installed...

scary huh... china still lives in the R-22 world of approximate charge is Ok.. even when dealing with 410a units...

-Christopher

[capthummel]

The best method is recover , vac & recharge by weight.

On some split systems there is a discharge service port so you can monitor discharge pressure.
In this case you can run the system in test mode & monitor the discharge pressure & discharge temperature with electronic temperature meter.
This will give you the 'discharge super heat'
Generally I find on R410a that if the DSH is over 45 deg C then that is good indication of SOG.
You can also take suction pressure , suction SH & compressor shell temp.
If the suction pressure is lower than you would normally expect but the SSH & compressor shell temp is higher than you would normally expect then that would also be an indication of SOG.

However all these readings can also indicate SOG if there is a slight blockage at some location in the system although the system is found to have a correct charge.

As LG make budget cost systems many features you would normally expect to find on a split system have been removed to make it as cheap as possible.
So while more expensive split systems are precharged for extended interconnect pipe lenght & have a large suction accumulator which tends to make the system less charge critical for LG the suction accumulator may not exist or is very small to save cost.
This make the LG split systems much more charge critical than many other split systems & just a few hundred grams can have an impact on cooling performance so geat care needs to be taken when charging the correct weight of charge.

If the charge weight is that critical how come it is charge with fifty feet of refrigerant and has a 25 ft line set instructions stated none need be removed unless you go under 15 ft or add if over 50. These spits are new to me as are the inverter tech. I come from a maritime background semi retired from it and I am amazed at the difference in standards for land vs sea. Seems to me they engineer these splits to install fast but neglect to think of leakage and maintenance issues it is very frustrating lol. I kind of miss that big ass crap I used to work on. At first I thought these splits where great but I have had many issues with flare nuts a stupid idea for refrigeration. Thank you for your info I will check for an high side access in the unit I just cant believe they only have access to the suction side on the service valve's another stupid idea.

[Thermatech]

I have never worked at sea as maintenance engineer
but
I have worked with some enginners who have spent years at sea.

The desigin of ac systems for use at sea is completely different from domestic ac mini split systems.

The ac of ships has to cope with any ambient conditions at any location on the globe.
The ac for domestic application is fixed for life in some front room or bedroom.
The ac for ships have to be maintained by engineer with limited resorces & spare parts.
The domestic ac can be maintained by specialist maintenance engineer with manufacturer backup technical support & next day delivery of any replacement spare part.
So the ship ac system needs to be able to cope with any extreem condition in the world & force 8 gale & no engineer working the engine unloaders every time the ship runs into the next wave otherwise the engine is going to blow the cylinder head off.

[eggs]

Yehhhhh! what he said......:D

Eggs

[capthummel]

I have never worked at sea as maintenance engineer
but
I have worked with some enginners who have spent years at sea.

The desigin of ac systems for use at sea is completely different from domestic ac mini split systems.

The ac of ships has to cope with any ambient conditions at any location on the globe.
The ac for domestic application is fixed for life in some front room or bedroom.
The ac for ships have to be maintained by engineer with limited resorces & spare parts.
The domestic ac can be maintained by specialist maintenance engineer with manufacturer backup technical support & next day delivery of any replacement spare part.
So the ship ac system needs to be able to cope with any extreem condition in the world & force 8 gale & no engineer working the engine unloaders every time the ship runs into the next wave otherwise the engine is going to blow the cylinder head off.

For sure we have to cope with allot more on the ocean especially big jumps in water temp in the tropic and marine growth make life difficult at times I guess I miss having complete control of my refrigeration systems at all times. And these poorly designed mini split systems just are pissing me off. But I do thank all of you for everyone's incite and help.

[Makanic]

[quote=capthummel;161402] Seems to me they engineer these splits to install fast but neglect to think of leakage and maintenance issues . I have had many issues with flare nuts a stupid idea for refrigeration.

neglect to think of leakage???
R410A and a Vapour leak !!
Its a Blend Refrigerant Vapour leak & its no longer R410A
wont be working efficaint
There is no Room for Leakage or bad flare's

[Yuri B.]

R410A and a Vapour leak !!
Its a Blend Refrigerant Vapour leak & its no longer R410A

It may be incorrect, but it's considered by some people that on a working system the leaking vapour contains, fortunately, the same proportion of the components the liquid has. So, a refrigerants blend does not degrade.