Does anyone have a Mitsubishi ductless minisplit commissioning procedure?
Is anyone very familiar with the commissioning process of a Mitsubishi Ductless Mini-split? I am a stones throw away from zone 6 and had a Mitsubishi diamond contractor install what was supposed to be a hyper heating condenser unit. Instead the contractor installed the MXZ-3C30NA2 which is a non hyper heat unit.
We had a couple days that we were down just below zero F and it seamed the unit was just maintaining. On the coldest day we had the remote thermostat set at 69F and the unit only was maintaining 66F. I have a well insulated 2100Sq ft. home that on paper should need 16,500BTU/H at -5F (With a lot of help from GBA).
When it warmed up I went outside to check out the condenser. I noted that the line set insulation terminated about 3″ from the flared fitting on the condenser. After closer inspection I noticed that the flared fittings have been leaking oil/refrigerant that is collecting in the pan of the unit. I have been having a lot of other problems with this Mitsubishi Diamond dealer/installer so I began looking more at the unit and realized it was not the unit they sold me.
After a conversation with the owner and them having to contact Mitsubishi to verify the unit they sold me was not a hyper heat unit. They are sending me the MXZ-3C30NAHZ that they sold me. I am pretty upset by now. I specifically questioned the tech as to whether the unit was a hyper heat unit because it did not have the H2i decal. He said not all hyper heat units had it.
Since I was working my regular job and building my home I had a lot of other things to do and figured maybe he knew what he was talking about. I really don’t have much confidence in this company but they are already paid and are coming back to try and do the job right.
Does any one have a Mitsubishi procedure for commissioning a ductless mini split? I have a JLC article with a Mitsubishi rep stating to pull a vacuum three times and replace with nitrogen before filling with the 410. I don’t want to but feel I have no choice but to bird dog this company. Oh yeah, funny thing they have 5 of 5 Stars on their google reviews, even though one of their employees told me every job customers are furious with one of their employees.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Dillon,
All the manuals you could need are on the http://www.mylinkdrive.com website. I would be extremely unhappy, they are different units for sure. I am having similar dealings with their "Diamond" contractors not leaving me confident or never responding at all.
Dillon,
I also just double checked the manuals for the 42NAHZ and 30NAHZ (I have the 42). Unless I missed something, in the 36/42/48 NAHZ call for the triple vacuum, first to 4000 micron, break with nitrogen, then 1500 micron, break with nitrogen, and finally down to below 500 micron. This is also after pressure testing the system up to 601 psig with nitrogen.
For the 30 the only thing I found in the manual shows pulling a vacuum once down to -14.7 psig and leaving for a few minutes before opening the valves on the outdoor unit.
I'm not sure why there is such a difference, but I don't think the extra steps to ensure the system is dry and free of air pulling the three vacuums is an issue, other than they don't want to spend the time doing it or use the nitrogen to break it.
Thanks Mike. Of course the manual tells you how to do it. Who knew? Does seem weird that the larger units have the vacuum followed with nitrogen three times (as described in the Journal of Light Construction Article) and the smaller multi head units only have a full vacuum pulled once. I also noticed a pump down section for lowering the refrigerant pressure when removing the unit, that should be helpful. Lot of good stuff on my link drive. That was how I realized I had the wrong unit. I also like the engineering manual for the M-series. That really describes the difference in the units performance across different conditions.
Dillon,
It looks like the information you need is on the mylinkdrive.com site, as Mike M. explained.
I hope that you report back in a few days and let us know what happens.
The hvac company installed the correct unit the other day. The air handling units seem to have a lot better delta T now even in the twenties. Thanks for everyone's help.