On Feb 20, 12:46*am, Steve Barker
wrote:
Sanity wrote:
"SteveBell" wrote in message
la.org...

The units themselves are just an air conditioner with a few extra
parts. The thermostats are a little more expensive, since heat pumps
require a 3-5 minute delay between off and on.

Your HVAC contractor can work the numbers with you for cost of
operation. Compare the costs of producing BTUs of heat for gas and heat
pump.

--
Steve Bell
New Life Home Improvement
Arlington, TX USA

You appear knowledgable concerning heat pumps. I live in Western North
Carolina. I have a combo unit. *Heat pump and gas furnace in the attic.
There is a point where the heat pump shuts down and the gas furnace comes
on. At first it was set to switch over at 30 degrees outside temp. *Since it
doesn't get too cold here, I found the heat pump running most of the time
and running excessively. They changed the setting to 40 degrees and the
house heats up almost instantly however , even though my electric bill
lowered slightly, my gas bill jumped through the ceiling. *Is there a temp
setting for the switchover that is more or less standard and economical?

the more you can run the heat pump and get heat, the better. *contrary
to what has been said here, the heat pump will almost always beat out
gas as long as there is sufficient heat being produced.

s- Hide quoted text -

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These messages about the auxiliary heat kicking in at certain
temperatures (above freezing!) seem to confirm what is being discussed
here.
With winter temperatures up and own from just above freezing to
sometimes as low 12 degrees F, or even lower overnight, the discussion
is that heat pumps that get their heat from an outside air coil are
not adequate.
Better are systems that pump the heat out of ground based coils or in
a few cases from some source of water. Although if the water source is
a well a lot of water is required.
We first heard of this during a rather cold winter some 12-15 years
ago, in brand new house, when heat pumps were relatively new.
Here we do not have natural gas and AFIK heat pumps systems using
expensive propane have not even been considered; so auxiliary heating
is electrcity.
In summary; with an air coil heat pump, during cold weather one is
heating the home primarily with electrcity. During those months the
savings are much lower.
Anyway just a comment.

On Feb 22, 10:19*am, Chris Hill wrote:
On Sat, 21 Feb 2009 14:02:22 -0800 (PST), BobR

wrote:

I measured the depth of the insulation in the attic and it was 15
inches deep which should be enough but it is a cellous insulation
instead of fiberglass and appears to be packed down. *I am not sure if
it is still doing any good and am considering adding blown in
fiberglass this spring. *I would have done it earlier except that this
stinking house has turned into a endless damn money pit and my
finances do have limits.

If the unit is as old as the house, that could explain the bills.
Also, if ducts are run in the attic, they may not have been sealed
very well.

No, the entire unit was replaced 5 years ago including all of the
ducting. I have checked the ducts and they are in great shape with no
leaks that I could find. Last night got down to about 30 degrees and
once again the only thing coming out of the vents was cold air. I am
going to call another A/C company to come and check it out yet again.
I am starting to think the best thing to do is simply burn money in
the fireplace.

"BobR" wrote in message
...
No, the entire unit was replaced 5 years ago including all of the
ducting. I have checked the ducts and they are in great shape with no
leaks that I could find. Last night got down to about 30 degrees and
once again the only thing coming out of the vents was cold air. I am
going to call another A/C company to come and check it out yet again.
I am starting to think the best thing to do is simply burn money in
the fireplace.
@@@@@@@@@@@@@@@@@@@@@@@

If it was only 30 deg outside and you are getting cold air then something is
wrong. Was this by feel or actual measurment ? Heat pump air sometimes
feel cold as the air may only be 80 to 90 deg comming out of the vents.
They will sometimes go into the defrost mode and put out cold air for a
short time.
It is time to call another company and have it checked out.

On Feb 21, 4:53*pm, BobR wrote:
On Feb 21, 9:12*am, wrote:

Bob, I think one big problem, and perhaps the only problem, is that
the backup is electrical resistance heat. *You're electricty cost, at
14.5c KWH is substantially higher than average. * Mine here in NJ is a
little higher than that.

You are right about it being the main problem.





Here's a link to two calculators from a previous thread. * The first
one was one I found, the second one Bubba provided. * Using them, you
can input the cost of electricity, cost of gas, heat pump efficiency,
furnace efficiency and find the temperature point below which it costs
less to generate heat with gas. *Whether a heat pump is cost effective
overall is going to depend on how much heat you generate above that
temp, versus how much you generate below it. * And keep in mind that
you could be generating a lot more heat below that temp, depending on
how cold it gets. * For example, it would probably take a couple days
of outside temps in the 40s to equal one day's worth of heat required
in the 20s.

http://www.shoreviewtech.com/hp_temp.aspx

I put 15c KWH and $1.50/therm gas into the above calculator and it
gives a transition point of 32F. *The $1.50 is my cost here in NJ,
don't know yours.

http://icpindexing.mqgroup.com/docum...VAC%20Equipmen...

On the above calculator, scroll to the bottom and go through the tabs
to get to dual fuel. *Using the same 15cents and $1.50 on this
calculator gives 22F. *Also, the heat pump efficiencies for either of
these calculators is for a efficient, modern unit. *IF you have an old
unit, obviously it could be different.

So, with a modern unit, and assuming your gas is $1.50/therm, a heat
pump should be efficient compared to gas down to somewhere between 22
and 32F. * I think the thing that is killing you is that the backup is
electric resistance heat. *With your high electricity cost, that
doesn't have to come on all that much to cost so much that you woulld
in fact be better of with just a gas furnace. *Also, this calculator
is figuring out when it's more cost effective to go to the alternate
fuel, not when you HAVE to go. * Meaning, below some temp, the heat
pump can no longer supply all the heat that is required. * And it
sounds like for your system, that point is close to 32F than 22F.

I'm curious. *With such huge bills, why haven't you just put in a gas
furnace? * Or a dual fuel system, where you'd switch to gas below the
transition temp? * With $700/mth winter bills, the payback would be
fast.

Simple answer is that gas is not available and city won't allow use of
LPG or propane. *I am STUCK with only one option and that is all
electric. *What makes it somewhat funny in a sick sort of way is that
we are sitting on one of the biggest gas fields in the country.- Hide quoted text -

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I'd also look into geothermal. It still is a heat pump, but with
ground water near 50F, it will be efficient in all outside temps.
While expensive upfront, with energy tax breaks and your existing $700
a month bills, it could pay for itself in a reasonable amount of time.

An energy audit, which sometimes you can get for free from the utility
company or a govt agency, would be a good idea. You might find some
missing insulation or similar that could be fixed very cost
effectively.

jumpnut30 wrote:
I live in the Dallas Ft. Worth area and I'm considering installing a
heat pump rather than a standard A/C unit. Any recommendations as to
reliability and efficiency?

You should check into a GHSP "Ground Source Heat Pump". I haven't
priced them yet but when I grow up I want one.

http://www.igshpa.okstate.edu/geothermal/faq.htm

http://tinyurl.com/bd3ha6

TDD