HVAC Mini Split Question

[Scra99tch]

Hi I had a quick question about a multi zone heat pump install. When you pull a vacuum on several installed heads is the whole plumbing liquid and gas line under vacuum? Or should you pull vacuum on each service port? Reason I ask is I've seen pictures of the interior and the all the gas lines are all plumbed together. But the individual zones liquid lines are all actuated through valves so can't be under vacuum?? If I have this correct.

I'd like to put these under pressure with nitrogen to check for leaks for <3 hours. Then pull vacuum for possibly even much longer say overnight but can't be there for 2-3 days to do both zones.

 

[Pevehouse]

On a typical a/c system you can pull a complete vacuum with only one port. High or low. Now the mini splits, I have no knowledge of but I figure a system is a system

 

[MikeInOr]

I installed a 3 zone mini split in each of my bedrooms. All zones are tied together. If you pull a vacuum on one you pull a vacuum on all of them.

Before installing the 3 zone mini split I did not know that you can shut off the entire high side port then put the outdoor compressor into a mode that compresses all the freon into the coils draining the lines... essentially putting the compressor back into the state it came in, containing all the freon in the compressor.

 

[Jim F]

Hi I had a quick question about a multi zone heat pump install. When you pull a vacuum on several installed heads is the whole plumbing liquid and gas line under vacuum? Or should you pull vacuum on each service port? Reason I ask is I've seen pictures of the interior and the all the gas lines are all plumbed together. But the individual zones liquid lines are all actuated through valves so can't be under vacuum?? If I have this correct.

I'd like to put these under pressure with nitrogen to check for leaks for <3 hours. Then pull vacuum for possibly even much longer say overnight but can't be there for 2-3 days to do both zones.

Vacuum checks for leaks.

 

[Scra99tch]

I installed a 3 zone mini split in each of my bedrooms. All zones are tied together. If you pull a vacuum on one you pull a vacuum on all of them.

Before installing the 3 zone mini split I did not know that you can shut off the entire high side port then put the outdoor compressor into a mode that compresses all the freon into the coils draining the lines... essentially putting the compressor back into the state it came in, containing all the freon in the compressor.

That’s good to know I’ll have to look into that because

Vacuum checks for leaks.

I’d like to test the connections for leaks by pressure first but have also been told not really necessary.

I keep running across mention of actually pushing it to 500-600psi as those are some of the extreme pressures that the unit will see.

 

[Scra99tch]

That’s good to know I’ll have to look into that because

I’d like to test the connections for leaks by pressure first but have also been told not really necessary.

I keep running across mention of actually pushing it to 500-600psi as those are some of the extreme pressures that the unit will see.

But yeah I’ll do the triple Evan with nitrogen.

 

[MikeInOr]

I had a hell of a time with my Mitsubishi 3 zone. I finally realized that the electrical connections on the compressor were:
1 - 2 - 3
but the line ports were
3
2
1
So I had wires for 3 crossed with the lines for 1 and vice versa. That is when I learned I could use the compressor to pump the freon out of the line set back into the compressor coils. There is a solenoid for every port on the compressor manifold which syncs with which interior unit is on... and getting freon.

I vacuumed the lines then pressurized them with Nitrogen and let them sit for a day. Of course after that I vacuumed again and released the refrigerant. I forget the nitrogen pressure I used for testing... but, yeah, it was up there. There is some "nyloc" or something sealant that I used on the flares... just the flared surfaces, not the flare nuts and not the outside of the flare that touches the nut.

The quality/expensive yellow jacket flaring tool was worth every penny!

I just used a quality set of Yellow Jacket gauges. I didn't buy the expensive electronic micron vacuum gauge. I think I ran the vacuum pump for a couple of hours just to be sure.

 

[MikeInOr]

One downside of the multizone mini split is sometimes my daughter wants heat in her downstairs bedroom while I want cooling in my upstairs bedroom. This can't be done. All units are heating or all units are cooling... it can't be some of each.

 

[Jim F]

That’s good to know I’ll have to look into that because

I’d like to test the connections for leaks by pressure first but have also been told not really necessary.

I keep running across mention of actually pushing it to 500-600psi as those are some of the extreme pressures that the unit will see.

A leak can hold pressure and not a vacuum.

 

[talvare]

A leak can hold pressure and not a vacuum.

Or vice versa. I've run into both situations several times.

Ted