Mitsubishi Mr Slim Heat Pump

[jlghome]

We installed a 3 zone Mitsubishi unit without the Hyperheating Inverter technology in the Fall of 2012. The unit works fine as a heater down to about 7 degrees above zero. But it is not much good below that. We complained to Mitsubishi and they added a single zone exterior unit that featured the Hyperheating Inverter and it has so far functioned very well down to minus 10 degrees (it is -9 right now here in Indiana). The brochure found here:

http://www.mitsubishipro.com/media/2264 ... ochure.pdf

would seem to be an accurate description of the capabilities of the new technology. We recommend the unit with Hyperheating Inverter technology but avoid anything else if you want it to work in really cold weather!

[mjr6550]

Brand new home, R-49+ in attic, 2x6 w/ high density batts.

Marc: Don't know size of cables to inside unit, what would I look for, are you talking refrigerent lines or electric cables??

BTW this was a ducted system: There was a unit or something I thought was a duct manifold in the attic

Outside today was 40 degrees, home temp was 62, took 1/2 hour to reach 68 in home.

HVAC Guy told me they do not (normally) have auxillary heat and possibly needs to be added, so I told clients to ask installer.

How you would tell (aux heat) or test it?

That unit is rated at about 16,000 to 18,000 btuh at 17 degrees and about 26,000 to 28,000 btuh at 47 degrees (I just looked it up). How big is the house?