Just installed ductless A/C 18000 btu .... Runs perfect Line temp question ?


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Old 05-13-14, 06:00 PM
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Just installed ductless A/C 18000 btu .... Runs perfect Line temp question ?

So I have more experience with aircraft and cars 134A . This got a proper install and extra length line weighed in charge ( 25ft to 36ft ). Super cold inside down to 35 F max R410a .

My question is the vapor and liquid line seem cool . high side is 70 f the low is 45 f , 90 f outside .

Most of my work has a large difference a real hot and cold when running hard . My condenser has a good 10 degree air temp difference from inlet fan to discharge .

I feel like burping an ounce into the recovery machine , Now fall into don't fix it , if it aint busted . Compressor current is normal . Whats your call ? Should the high side be hotter ?

Thanks Heli
 

Last edited by Heli-tech; 05-13-14 at 08:51 PM.
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Old 05-13-14, 09:16 PM
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I'm not an expert on mini splits. But I believe both copper lines are are actually low side.
 
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Old 05-14-14, 01:49 AM
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I'm not an expert on mini splits. But I believe both copper lines are are actually low side.
Depends upon the particular machine I suspect but my Chinese unit has capillary tubes for both heating and cooling cycles located in the condensing unit. That means that both tubes of the lineset are downstream of the expansion device whether in heat or cool mode. It sounds like a poor method to me but then I have been away from all things in the refrigeration world for several decades. I DO know that there is a very real pressure differential at the service valves in either mode, probably due to different lengths of cap tube for the different modes.
 
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Old 05-14-14, 04:42 AM
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Well , according to the paperwork it shows a low and high side . I haven't done a mini split install of this type before . It shows good numbers for temp and pressures for the indoor and outdoor unit . The asian or euro units need a 5/16 to 1/4 adapter to use R410 gauges / hoses , that can be found on eBay / some locals. That R410 can run 300 + psi on the high side .

Just seems odd not to have a hotter high side . I was going to post a video for others to see the how to . I think the easiest DIY would be the stock line set , with only a vacuum pump needed on a smaller 110 volt unit 9000 - 12000 BTU . Keep the power bill low just cooling an office or bedroom .

You could pull down a vacuum and opening the charge valves ( pre charge unit ). While these smaller units use aprox. 1000 watts or under .You could use an outdoor 110 V plug . Its better to have circuit just for the unit a low use circuit to a patio or garage would handle it .
 
 

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