On Aug 31, 10:32*am, Mac Cool wrote:
I'm in North Carolina so the weather is relatively mild. I would like to
switch to a heat pump. According tohttp://hes.lbl.gov/hes/about.html, I
could conservatively save about $1600/year on heating alone. I was as
thorough as possible when completing the survey. Last year my hvac guy, a
friend of the family, told me I wouldn't recoup the cost of replacing the
propane but I'm spending thousands each winter on propane. My propane
company has kept the price right at the break even point with electric, or
a little higher when it gets cold. The central unit is 7-8 years old,
propane heat/electric ac.

I'm going to sit down and discuss this with him next week. What are my
concerns and what questions should I ask?


there is a core level difference between these two options..

with propane, say kept at the same exact price as electric heat per
BTU you still pay drastically less for heat with a heat pump... key
word 'pump'. with a heat pump you are *not using the electricity to
heat a resistance heater to produce heat directly. You are using
the electricity to *pump heat from outside to inside... by running the
heat pump compressor. That is vastly more efficient than burning
propane, or using electricity in an electric heater.... 'burning
electricity' so to speak.

Even if its say 40F outside, you can pump the heat out of that air...
via the refrigeration / compressor circuit in a heat pump..


When it gets much below 35 or 40F outside a heat pump begins to loose
its advantage, so are not seen as comonly in very cold climates.
These do come with electric resistance booster heat though for times
when it gets colder than the ideal range for heat pumps.. allowing you
to reap the advantages of a heat pump while, having the capabilty to
heat on the rare occasions its below 35 or 40 outside... it i not
nearly as efficient in the pure electric heat mode though. no big
deal if its only say 10% of its run time.


My guess you will save between 30 and 50% on heating costs by going to
a heat pump ...

**

If you want to really save money, go to a zoned system, Many ways to
do that. say one smaller heat pump for the bedrooms, used at
night... and one for the living areas, used in the day. then program
them to set back in hours those rooms are not in use... that will save
another 20 or 30%.

If you add an electric matress warmer you can run the bedroom system
much cooler at night saving a lot more money.


***

two systems have the advantage of redundancy... when one dies, you can
still live in the house.
.....also two smaller units will tend to run nearer 100% of capacity
when each runs.. thats more efficient.

**
to save more undersize the systems by 20% or so.. this means for
instance that in the summer it may get up to 76f in your house between
3 and 6 pm (gasp)... but you will save on first cost, and run closer
to 100% of max load when you do run. (in humid climates there are
some caveats I wont get into here).


go with 14 seer units though...highest efficiency.. for many reasons,
operating costs and what that does to vastly extend the life of the
systems. Go with an ultra simple system (not carrier for
example)...Rheem is superb... Trane is not so bad. Complex systems
cost a lot more to repair.

**

to save a whole lot more, go with ductless systems.. these have a
component that mounts on the wall or like a radiator near the floor...
eliminates duct losses.. about 10%... and can zone to operate one room
at a time.. very very efficient... saving another 20% on top of the
two unit zoning I mentioned earlier. Not cheap to install though.
Daikin Kogyo and Mitsibushi both make them. The chinese are now
making them if you can find em, for about 70% less using the japanese
compressors (superbly reliable roller compressors)... search ebay.


The quality of the installation is crucial for whatever you get. ...
unless its window type heat pumps.. one in each major room. and dirt
cheap btw... offering 100% zoneabilty... when it dies just shove
another one in the opening. yourself... no service call. Most
major motels and many hotels have gone this route for those reasons.

***

geo thermal, using ground water for a heat source... very efficient.
costly to install and service.. easy to screw up the engineering,
local ground water issues vary..can be a big problem. for a large
building maybe the complexity is worth it... not for a smaller
home ..... imo. ymmv.


Phil scott.. in da business since 1810.