Just bought a house that's all electric and has a heat pump for heating.
Is that a good choice for the Midwest region? We're installing a gas line for a
fireplace and I wonder if I shouldn't replace the heat pump with a gas unit when
it dies. It's 18 years old now so I don't see many more days of life in it.
How about the water heater? Gas or electric?
It all depends on the rates you are paying. In most areas of the
Midwest you are going to save using gas over electric. In the case of home
heating/cooling it is not so clear. The total cost of heating and cooling
using a heat pump is likely to be near the same cost as gas heating and an
standard A/C unit. Heat pumps tend to be more efficient than single use air
Generally a heat-pump will use electrical strip heaters for the second stage
or for backup heat. You can also have a heat-pump use gas for the same
One more thing to think about, standard air conditioning is allot easier to
work on than an heat-pump to allot of technicians. If the company you are
using and you feel they know what there doing, no problem.
Agree w/ Joe...what are current rates and what is the outlook for NG in
your area as well as where in the midwest? The colder/longer the
winter, the less advantage of the air/air heat pump owing to the lowered
effectiveness -- once air temp gets much below freezing, the heat pump
really loses out and has to run much longer and as someone else noted,
you may be heating w/ resistance heating much of the time, anyway.
You might consider another alternative as well -- the ground loop heat
pump. More expensive to install initially because of the need for
burying the heat exchange loop, but if have sufficient area available,
can eliminate the need for resistance heating entirely and will
definitely be better efficiency than the air/air.
The switch out on water heating is almost entirely one of relative fuel
costs. The one other advantage of gas imo is if you have hard water,
the amount of tank fouling is much less w/ gas as the point-source
heating electrodes are much worse for that ime...
I plan to install a ground source heat pump when I replace my HVAC
eventually. One thing to keep in mind is that there are several ways to
install the ground loop and some installers are still pushing the
somewhat obsolete and much more expensive drilled vertical loop
installation or long loop horizontal installations. The newer trenched
vertical coil type installation is much cheaper to install and has been
proven to be equally efficient as the older methods. The trenched
vertical coil method cuts a narrow trench to a suitable depth and then
installs the loop piping like a flattened stretched out slinky.
On how much capacity you need, where you are, type used...
In most locations you'll want it at a bare minimum of 4-ft and it should
be 6-ft or so to minimize the thermal swings (winter _and_ summer).
For a ranch w/ fully furnished basement of roughly 1700 sq-ft per level,
we had about 400 lin-ft of trench in E TN. As noted, there are some
newer techniques since then that may cut down the actual size needed.
I personally recommend talk to your local Water Furnace distributor. At
the time we did ours (15 years ago now, almost!!!) Oklahoma State had
the recognized best collection information source out there along w/
TVA. I've not looked recently to see, but I'd start there.
It cut our heating/cooling costs by nearly two-thirds over the air/air
unit it replaced...
We moved in '99, but just a year or two ago another friend in the
neighborhood still mentioned via e-mail he had seen the fella' who had
bought the house and asked and the unit was still fine w/ no maintenance.
A heat pump quickly looses it's efficiency advantage over resistance
heating when the temp falls below 35F. If you live in a "cold"
climate area, unless your electric rate is very low, gas is usually
more cost effective.
Quite likely, which is why you have to specify "geothermal" or "ground
source". The air source units work ok in areas with outdoor air
temperatures that don't get too cold or hot, and are still cheaper than
ground source. Ground source have the advantage of near silent operation
in all cases since they don't have a big outdoor fan.
First, get a good crystal ball and see what the utility rates are going
to be over the next 20 years. In my area, both have increased, but gas
has increased more. You should also find out the source of your
electricity; my sister lived in upstate NY and their electricity was
from the falls; I don't see the cost of that increasing as much as in my
area, where it is virtually all from generating plants. Incidentally,
I've read that many electrical power suppliers are building new plants
that use gas; that should increase the cost of both.
If your home now is all electric, you should find out how much it will
cost you to have the gas hooked up; if that is thousands of dollars, for
example, that could eat up a lot of savings from making the switch.
My understanding is that heat pumps are more efficient, but need a
supplementary source of heat in areas where the winters are quite cold.
On the other hand, the good cooks that I know all prefer gas for
cooking, and I have never heard of the gas being knocked out by a storm
Steven Andrade wrote:
I'd revise that slightly as geothermal / ground source heat pumps _may_
not if sufficient heat source/sink capacity is available since
their coils are below frost lines and soil temps are relatively stable.
The point is that the 55F stable point is below the typical loop burial
depth as starters so the ground temperature around the loop will
rise/fall slightly w/ the seasons and it also isn't a perfect conductor.
Particularly when as a heat sink in the summer, temperatures near the
loop in the trench tend to rise.
When we installed the system in TN, it was the first buried ground loop
the installer had done (he had been working exclusively in a new
subdivision on a lake frontage area where loops were submerged in the
lake), so we instrumented the trench in several locations for the
information on how it differed as he was soon going to be in an area
that the distance to lakefront was going to make it impractical.
Even at 6-ft in a place no more extreme than E TN, the soil temperatures
were not constant.
As I said, "55 or so". The soil temp is certainly far more stable than
the air temp, and again, a properly sized and installed ground loop will
have no issues. The nice thing about the ground loop is that since it's
just plastic pipe and the trenching is an easy install method, you can
readily calculate the correct loop size and then add 25% as a safety
margin since an oversized loop doesn't cause any issues and only costs a
bit more tubing and trenching. When I do my system I intend to do just
this as well as increase the trench depth some, again with no risk of
causing any problems, only adding safety margin.
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