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Discussion Starter · #1 ·
I just ordered a 24000 BTU 3 zone Minisplit with 2x 12000 and 1x 9000 BTU mirror cool wall units.
I'm doing a second story addition. It is going to feed about 800 sqft but one of the units will feed into the rest of the house down the stairs.. I have a 2.5ton heatpum system on the first story (1500 sq/ft)..

Got a great deal on the new equipment. I was going to do the Mitsubishi units but decided on the LG for cost reasons. I was considering some other off brands, but didn't like the efficiency numbers. Ultimately cost vs efficiency is what made me choose LG..
 

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Put in some wood and/or sheet metal before you close it up with drywall. I'd put a strip of sheet metal down both sides of the piping just for protection and warning. It's not so necessary if you will remember where everything is after you seal it up, but it's nice to the next guy if you move out.

Cheers!
 

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Discussion Starter · #12 ·
Yaa.. I was also thinking of printing out some labels too. I put the nailing plates Around it, l will do the metal and plywood thing.. On the upper floor it routes right next to the toilet and it is 2x6 walls. The lower story wall is more likely to get nails, or the Comcast guy..the plywood and sheet metal and little plaque label should help..

Warning! Concealed floor to ceiling refrigerant lines in this area. Do not puncture!
 

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Discussion Starter · #14 ·
How much pressure do you choose for the nitrogen pressure test? The unit says ~550 psi max or so, the LG YouTube video said test to 150psi.. Is there a benefit to press it to the limit? If you over torque the flare or have a poor flare connection, will the pressure test reveal it? I feel good about getting the torque to spec but I'm a little worried that some of my 1/4 flares are not as good as they could have been..

My nitrogen regulator will go to 600psi..
 

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Not sure if you have installed the drain line(s) yet. That corrugated drain from them seems to be a problem with algae growing in them and plugging later. Ideally you want a large smooth solid drain line after them and make sure it has no sags. Sags collect scuzz and algae later especially in the off season. Try keep the one from the unit sloped down with NO sags.

With refrigeration flares a old rerig. Journeyman I worked with as a apprentice told me a trick. You tighten them and loosen them 3X as it stretches and works the copper and seats it to the brass seat. I use 250 psig for leak checking and NuCalgon gas leak detector soap. Can find even the smallest of leak as long as you watch it for 1-2 mins. No need to go higher IMO.

Use a mirror and magnifying glass and good light and it works great. The flare should be large enough that the nut just barely passes by it. You can also look at it on the brass seat with the nut pulled back to make sure it covers it properly.

http://www.nucalgon.com/products/gas-leak-detectors/gas-leak-detector
 

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CSA b52 wants at least 232psig for r410A. It "shall" hold that pressure for 2hrs, unless overruled.
(5.10.4.2 and table 4)

In a larger system where the high and low side can be isolated, they would want at least 444psig to the high side only, but I don't recommend it on a ductless split. I personally test to 250-300 psig on those.

Cheers!
 

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Just a small note, I've seen many a leak show up at 400+ PSI that wasn't detectable at a lower pressure.
When we do a startup, the installer is required to put a minimum of 590 PSI on the system for a minimum of 24 hours. Then we do a 200 micron evacuation.
I've also seen joints start leaking when they heat up but with a 590 psi test charge the chance of having further leaks is very low.
 

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Just a small note, I've seen many a leak show up at 400+ PSI that wasn't detectable at a lower pressure.
When we do a startup, the installer is required to put a minimum of 590 PSI on the system for a minimum of 24 hours. Then we do a 200 micron evacuation.
I've also seen joints start leaking when they heat up but with a 590 psi test charge the chance of having further leaks is very low.
The evaporator on a straight cooling unit may not be rated for such pressure. You do have to look at the rating plate before pressurizing. Otherwise, your right, some leaks are painfully slow even at higher pressures.

Cheers!
 
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