DIY Install of Mitsubishi Mr Slim Heat pump

bonzgirlSeptember 14, 2011


We bought a used Mitsubishi Mr. Slim and uninstalled it from another home in Seattle and have mostly installed it in our own home. It was fully functional when we removed it and we followed the pump-down procedure in the manual to pump the R410a down to the outside unit and store it there.

Now we've got it all hooked up at our new house... concrete slab is poured,

outside unit is bolted to it, the 220v single-phase electrical is run,

inside unit is hung, hole drilled on outside wall, gas and liquid lines are all connected. Drain line and electrical connect are active. The system powers on and appears ready to go.

We sweated the copper lines together - we had to cut them out of the old house. Got lucky and the refrigerant lines were a little longer than we needed so we kept some extra but removed about 6 inches of each. No right angle bends anywhere.

Now it is time to pump the air out of the lines and release the coolant.

We dont have a vacuum pump/gauge set up and they are expensive to

buy for a one-time deal... plus, we feel like it would make sense to have

a professional do this for us. We're not keen on releasing R410a in to

the atmosphere... its environmentally bad and expensive to replace.

So finally, the questions:

1) What should we expect to pay for a service call to visit our home, do a vacuum procedure and check for leaks, then release the R410a from the outside unit in to the system lines? (Seattle, WA)

2) Can the tech check to make sure that there is enough R410a? how does this work?

I realize this is a tough crowd in here, go easy on us, we're newbies, but

thanks in advance


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I would think a couple hundred bucks the most...if that. If you called me, it would be an hour labor + freon. Don't think about just opening that low side valve and letting the gas in the system without a vacuum.... air/moisture +410A oil don't mix at all.

Hope this helps

    Bookmark   September 14, 2011 at 8:55AM
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"We sweated the copper lines together..."

Refrigeration lines are normally brazed.

    Bookmark   September 14, 2011 at 12:40PM
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I think they used silver soughter. 300 bucks

    Bookmark   September 14, 2011 at 2:40PM
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I guess you download the installation manuals to get the pump-down procedure. If you have done this correctly so far, brazed the lines, I would think you could finish it with rented equipment. I would like to see the lines evacuated, purged with dry nitrogen and then evacuated again before filling. That leaves you with checking the charge. That will be the trickiest part so if you are going to hire someone for that, OTOH, you might as well have them do the rest of the stuff.

    Bookmark   September 14, 2011 at 8:36PM
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u need a real professional, you gonna have problems. the pumpdown is nice. but it should be removed, then weighed in based on the length of line-set. If you brazed the copper w/o using nitrogen you are adding carbon flakes to the inside of the tubing to mix with the oil and this is conductive, not good for compressor. 410A must have a dryer added and a sight glass, inorder to determine if U have remaining moisture. U must vacuum down to approx. 500 micron, need micron gague. and make sure the replaced 410A is weight back in. Get a real professional to do this..did U not save enough by reusing and moving the unit? Dont go cheap at this stage of the job.

    Bookmark   September 18, 2011 at 10:16AM
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Did you have this done yet? We had our exterior unit moved (in Kirkland) last year after a remodel. We chose a different contractor than who did the initial install. I liked them much better.

(Greenwood Heating/AC is who did our move).

    Bookmark   September 26, 2011 at 7:42PM
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