Dual Zone Mini Split - Vacuum/Charge Lines

SWBriscoe · Oct 23, 2023

Building a new shop and purchased a Cooper & Hunter Dual Zone Mini Split. I have set up several Mini Splits in the past in a field setting (Iraq) and all seemed to work fine (considering the environment). These were all single zone units so I have never vacuumed and charged a dual zone unit. Provided instructions are sufficient but I cannot find any clear indication about vacuuming and charging the lines (pre-charged unit). I believe both lines are vacuumed, tested and charged separately as if two single zone units. Can someone clarify that for me? I don’t want to charge one line, then vacuum the second only to suck out all the refrigerant from the 1st line.

Thanks

in advance for any assistance And advice.

roughneck · Oct 23, 2023

You forgot the part about the nitrogen pressure test. Are you planning to do that?

SWBriscoe · Oct 23, 2023

Yes, again, separately?

roughneck · Oct 23, 2023

Probably.
I’ve honestly never heard of that brand name and some of these are set up differently then others.

user_12345a · Oct 23, 2023

roughneck said:
Probably.
I’ve honestly never heard of that brand name and some of these are set up differently then others.

I think those units are made by midea.

SWBriscoe · Oct 23, 2023

Cooper & Hunter seem to have good reviews, not the cheapest model but not the most expensive either… all the ones I set up in Iraq were Mitsubishi. Pretty easy to set up and gave me something to do between requirements. I’m 98% certain the lines are set up separate but it’s the 2% that always get me in trouble. Could hire an HVAC guy to do it but, to be honest, not interested in paying hundreds of dollars to a guy to hook up a vacuum pump, gauges and nitration bottle then stand around for 2 hours when I stand around just as easily and not have to pay outrageous amounts.

roughneck · Oct 23, 2023

What’s your target test pressure with nitrogen?

SWBriscoe · Oct 23, 2023

I’d have to look at the book again to verify, recall vacuum pressure at -30 give or take.

SW Dweller · Oct 23, 2023

I would get ALL the lines done and tested and vacuumed to >100 microns before I opened the valve where the charge is. Make darned sure that the total length of piping is less than the charge in the compressor.

roughneck · Oct 23, 2023

SWBriscoe said:
I’d have to look at the book again to verify, recall vacuum pressure at -30 give or take.

You should be using a micron gauge for evacuation. Not an analog gauge. 30” isn’t sufficient.
Nitrogen test pressure should be a minimum of 450-500 PSI.

Dual Zone Mini Split - Vacuum/Charge Lines

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