installing minisplit heat pump- questions

Mitsubishi's are very good, daikin and others are not bad either.

Size it with loadcalc.net. Other sites work too. For the attic, you'd use either a separate system, or a multi head version" (look at Mitsubishi's r2 systems)

It's very possible to do the job yourself. Do a search on here, it's been talked about several times. That will get you started on the right path, then ask more questions here.

Mitsubishi, daikin, LG, york, etc all do a fantastic job during both sides of the heat pump cycle. "making heat" or rejecting it for a/c, are both very adequate. Even in places much further north, like Alberta or Ontario, etc. I've seen Mitsubishi air source HPs used for primary heat for whole buildings here. (No backup heat)

Cheers!

Minis do a fantastic job. Whoever told you they are useless below 40 doesn't know the facts.
Mitsubishi will not warranty DIY work.

http://www.mitsubishicomfort.com/internet-sales

You can do the whole job with proper tools( vac pump, nitrogen, micron gauge, flaring tool to name the big ones)
You may be better off doing the bulk of the install and having an hvac tech make connections and commission.

I think mitsubishi has a sizing chart somewhere. Not sure where but just search for it.
They do heat very well. I heat almost primarily with one in Vermont. The GE models heat down to 5f. FE and FH models heat down to -18f. I have an FH-15 and 1150 sq ft ranch.

There are still lots of people who think that heat pumps don't work below 40. Technology has changed a lot in the last 30 years...

check www.loadcalc.net its free - other threads trending others are doing DIY installs. Buying the tools, equipment needed etc. You can always re-sell the tools etc if needbe. Be REAL careful with the flares (copper) buy the torque tools to tighten the flare nuts!! Diff n R410A just higher pressures.

i have one mz-fh15 Mitsubishi and it heats even at -10F in canada. so at 30F there is no problem at all

Easy installation. A DIYer should be able to handle it.