Final mini-split install Qs

[Scottmcll]

Hello All,

The info I've found in other threads regarding DIY mini-split installations has been invaluable, and I am very appreciative.

I am now at the stage in my own, 3 zone, install that it's time to pressure test, evacuate, and release the 410a. I purchased pro equipment to do the job and I just have a few lingering questions I'd like answers to, along with any advice, before proceeding.

First, the manufacture and seller of my unit, Thermocore, does not recommend pressure testing the system with nitrogen. They say pulling and holding a deep vacuum is check enough. It just seems to me that applying pressure is a better way to check those flare connections. Opinions/advice?

Next, if I do test with nitrogen and there are no leaks, I assume that I evacuate the nitrogen with the vacuum pump in the same operation as pulling the deep vacuum ahead of releasing the 410a, correct? Does pulling the vacuum assure there is no nitrogen left in the system to contaminate the refrigerant?

I will begin with fresh oil in the pump. Will I need to change the oil between each zone vacuum operation?

Next, I am using a core removal tool on my hose setup. After pulling the deep vacuum on a zone, do I reinsert the valve before I release the refrigerant, or after?

And lastly, am I correct that I proceed one zone at a time? Meaning, beginning with zone A, pressure test, evacuate, release refrigerant, power test, then on to zone B, according, then zone C?

Thank you, Scott

 

[WyrTwister]

Maybe I can help with a few of your questions . I have done 2 MS installs , but they both had single indoor units .

If you pressure test with nitrogen , you have to have a regulator . Now , if it is 100 F outside and you have a jug of R410a , the inside pressure , in the jug is going to be 317 - 318 PSI .

So , if you set the regulator at about 300 PSI , I can not see how you are going to damage the MS ? Just build the pressure up very slowly .

The MS'a do not contain a whole lot of air ( or nitrogen ) in the inside coil + line set . I am not sure it is necessary to remove the Schrader valve , to vacuum the system down .

I have read to use fresh oil , every time . I honestly do not know if this is really correct ?

Do you have service valves & Schrader valve ports for each " loop " ? If so , I would purge each loop , pressure test each loop , vacuum each loop and lastly release the refrigerant for each look . But , as I said , I have not done systems with multiple loops .

God bless
Wyr

 

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[Scottmcll]

Thank you Wyr. I appreciate the feedback from someone who's done this before. Cheers.