[Shop-talk] Heat pump water heaters?

[David Scheidt]

On Sat, Nov 24, 2012 at 12:47 AM, Dave C <cavanadd at frontier.com> wrote:
> I must not get out enough.  I saw an ad for these in tonight's paper.  I
> never knew they existed.  I understand how they work, and I guess if natural
> gas was unavailable and your electricity was really, really expensive, they
> might pencil outr, but it looks to me like a (very complicated) solution
> looking for a problem.

Well, they're in range of 250% efficient, so for straight out
replacing a standard electric water heater the pay back period is
somewhere around 3 years. Depends on your electric rates, of course,
and your usage.  Also depends on climate: if you're somewhere like
Florida where you're likely going to be paying to air condition air
much of the year, you get a double bonus, since the heat moved into
hot water is heat the air conditioner doesn't have to deal with.  If
you're in Alaska, it probably doesn't make any sense at all.

If you're looking at replacing a gas heater with one of these, the
payback is longer.  I don't think anyone makes a residential heat-pump
with gas backing, so you go from a relatively cheap heat source to a
more expensive one.  There are add on things, and heat pump/gas
hybrids exist for commercial operations.

The management company my coop uses has told us if we replace the hot
water boilers with a heat pump system, we'd pay back the capital costs
in between two and three years, and book a savings of a few thousand
dollars a year after that.  (We have common hot water, paid for by the
association, and people use a lot of it. )  Given the expected life of
the system is a few decades (current system was installed in 1959, and
works just fine), that's a substantial amount of savings.


-- 
David Scheidt
dmscheidt at gmail.com