Friday, September 12, 2014

Dual Hose Portable Heat Pumps Don't Work Well in Practice

For years I've wondered if a dual-hose portable heat pump/air conditioner would work as a poor man's ductless minisplit heat pump. The advantage, as my logic went, was that I didn't have to drill any holes or charge any refrigerant.
I bought a 14kbtu portable heat pump (Edgestar AP14001HS Portable Air Conditioner)
I did some primitive temperature and airflow measurements.
I was impressed by the overall quality and the 11.2 EER, but what I found was very disturbing.
There is so much internal leakage, that the heat pump blows almost twice as much air out of the house that it pulls in. That difference in air volume gets sucked from outside into the house. The net effect of that is to reduce the COP in heating mode from the advertised 3.3 to roughly 1.4.
For heating, that makes it hardly worth the extra money over a resistance heater. I might as well have purchased an electric resistance heater with a COP of 1.0. In the air conditioning mode, this problem makes the unit worthless except for spot cooling. A window unit would work three times better at a lower first cost.
Has anyone seen a dual hose unit that actually works well?

Monday, September 8, 2014

Pretty Good Duplex HERS Scores

We just finished and sold both units of a spec duplex in SW Denver.  The HERS scores were "pretty good" at 59 and 62.

One of the more important components of the HERS score is the infiltration measurement.  Building Joe Lstiburek identifies 3.0 ACH50 as a pretty good goal.  We scored a 3ACH50 without trying very hard.  The main reason for the good score was the "flash and fill" insulation strategy.  About 3 inches of polyurethane spray foam was sprayed on the inside of the sheathing, and the rest of the cavity was filled with cellulose.

Did the HERS score even come up during the sales or marketing process? Not at all.   Was it good experience for our building professionals in anticipation of the IECC 2012 requirement of 3.0 ACH50?  Absolutely.

Heat Pump Dryer Update

Apparently production of the LG heat pump dryer for the US has been stalled.  A call to customer service yielded no knowledge of it.

But now there is a report that Whirlpool will have one available Q4:

Friday, September 5, 2014

LED lighting update 2014

The LED bulb market is still changing quickly, but IKEA has a 600 lumen dimmable bulb for half the price of the 60 watt equivalent Cree:
The Cree bulb is on the shelf at HD for $9.97:
The Cree is 84 lumens/watt and the IKEA is only 60 lumens/watt, so the Cree pays for itself in 3yrs, assuming 3 hours usage per day @ $0.13/kwh
My wife also thinks that the Cree can go dimmer.