Friday, June 22, 2012

Done (almost)

This week's project has been to equip our main floor with air conditioning. Like most New England homes, our home was plumbed with hot water heat. When we moved here from Michigan 15 years ago, our builder convinced us it didn't get hot enough in New Hampshire to warrant forced air heat in order to accommodate central AC. I regret not challenging him on this.

Options available to us were a) use many window units (hugely inefficient, ugly, and labor intensive, b) run ducts through the house with an air handler in the basement or attic (disruptive, very expensive install), or c) install a split ductless AC system with the evaporator unit installed on a wall (some might protest aesthetics).

The ductless systems are very popular in other parts of the world. These are also among the most efficient systems.  Some people in nicer, modern homes, might not want an evaporator unit with fan mounted to an interior wall. Cathy and I are not that fussy.

We went with a Mitsubishi ductless system, a 2-ton (22,000 BTU) unit with a SEER rating of 19.  Misubishi AC systems are highly rated and thus not cheap. The compressor uses inverter drive technology. You barely can hear the compressor turn on when standing by the unit outside.  The only external wall that had enough space to mount the indoor unit on was our dining room, a room rarely used.  The dining room is open to both the kitchen and foyer, two paths for air to circulate through the rest of the main floor. The fan in the unit is whisper quiet, nothing like a window unit. You pretty much have to walk right up to the unit to feel air movement to tell it is running. With a single unit on one side of the house, I do expect some temperature gradient across the house. My study in particular, is at the opposite end and has one narrow doorway. But the room with our home theater in the middle should cool just fine.

The system came Wednesday from I wired the 220V to outdoor compressor Thursday and finished the copper and drain lines with inter-unit wiring this morning on my off-day. I had Rob Coletta swing by after I finished the install to pressure test for leaks, vacuum purge the lines and perform start-up. I was super-stoked Rob had an open slot at the end of the day and could get me going before the weekend closed out.  By the time Rob left, our main floor was cooling down. Would have been nice if I had started this project a few days earlier with recent heat...

Compressor unit. Stands about 3ft high but only a foot or so wide.
Three cement blocks and two patio pavers form pedastal.

Evaporator unit.

The system was quite easy to install. As an electrical engineer and having built an entire house in Michigan, I have good familiarity with electrical code. The most challenging part was drilling the 3" hole through the wall and then getting four items (liquid line, suction line, drain line and electrical conduit) through that hole while holding up a 60 lb unit. The compressor is pre-charged with R410A refrigerant. My line length did not require any additional charge.

Still a couple loose ends to finish. The inter-unit lines finishing kit did not make it with the shipment. On back-order. So exposed lines will have to hang on the side of our house another week or two. Also need to anchor the compressor unit to the base. It weighs over 130 lbs, so it won't be going anywhere in the mean time.  Might have to move the bike stand upstairs now...


Naoki Dieter said...

Same as you, I prefer the ductless AC. It is space-saving, and if you choose the correct horsepower, it certainly is more energy-efficient. Plus, it is quieter and much easier to install. Have fun using your newly installed mini-split!

Darryl Iorio said...

My family just recently bought a ductless AC and even if not one of us has any background on electrical codes, still, we were able to set it up! It is quite easy, actually. We just followed all the instructions written on the manual, and voila, our new AC successfully installed! :D

Unknown said...

Good thing I followed our contractor's advice to get a ductless AC! Like what Naoki said, one big advantage of is it is that it is energy efficient. Don’t forget to clean your filters once in a while and have your AC checked for regular maintenance.

-Georgia Fuller