Using an air conditioner as a heat pump

Posted by on October 6, 2008, 7:08 pm

On Oct 6, 1:24=A0pm, .p.jm@see_my_sig_for_address.com wrote:

> >If inquiring minds *REALLY* want to know, they should be calling their
> >local, competent, licensed, insured, professionally trained, HVAC techni=

cian

> >to do the calculations, and explain the best options for a properly size=

> >and correctly installed comfort system.

I used to do the calculations for heating back in about 1973 and 74.
Can't remember if we even had a calculator then. Calculators were
pretty expensive then, but sliderules were plenty accurate for heating
calculations. As I remember the FHA booklet had good explanations of
how to do the calculations.

When I get moved I may take a tech college course. HVA Engineering
Design As an old guy, I can take it for pretty much no cost.

" Residents of the State of Delaware
who are 60 years or older may enroll
at Delaware Technical &
Community College, tuition free in
any catalog (credit) course:
technical or related studies, day or
evening"

Any of the group here from Delaware? Nearby Pennsylvania?

Dan

Posted by Steve on October 7, 2008, 8:31 am

> wrote:

>>> Do you want it cheap?? or do you want it right??

>>Actually I want to increase my knowledge in how air conditioners
>>differ from heat pumps. Could a heat pump be produced at roughly the
>>same cost of a air conditioner if it were made only to heat the
>>building? Or are there differences that require additional costs?
>>Would a capillary tube work for a heat pump or is a expansion valve
>>necessary? Does the evaporator coil need to be much bigger?
>> Inquiring minds want to know
>> Dan
>>--------------------------------
>>The difference is the reversing valve, and accumulator.... other than that
>>they are the same....

> Wrong. You forgot defrost control. Critical element.

Sheesh...minor details :p

>>. Size it for heating in your area... Do a Manual J
>>calculation to correctly size it, and a Manual D for designing the
>>ductwork
>>for correct airflow to each room.
>>FWIW, all the new equipment has expansion valves in it. Stay as far away
>>from R-22 as possible, use equipment that takes R-410a refrigerant.
>>If inquiring minds *REALLY* want to know, they should be calling their
>>local, competent, licensed, insured, professionally trained, HVAC
>>technician
>>to do the calculations, and explain the best options for a properly sized,
>>and correctly installed comfort system.

> --
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> www.theanimalrescuesite.com/
> Paul ( pjm @ pobox . com ) - remove spaces to email me
> 'Some days, it's just not worth chewing through the restraints.'
> 'With sufficient thrust, pigs fly just fine.'
> HVAC/R program for Palm PDA's
> Free demo online at www.pmilligan.net/palm/
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Posted by on October 6, 2008, 7:21 pm

> The difference is the reversing valve, and accumulator.... other than tha=

> they are the same..... Size it for heating in your area... Do a Manual J
> calculation to correctly size it, and a Manual D for designing the ductwo=

> for correct airflow to each room.
> FWIW, all the new equipment has expansion valves in it. Stay as far away
> from R-22 as possible, use equipment that takes R-410a refrigerant.

Thanks. You can easily tell that I have not done any real work.
Just read some books. The books all have lots of information on
capillary tubes and I figured that window units would use the least
expensive thing.

Dan

Posted by Stormin Mormon on October 7, 2008, 8:55 am

The window units I've seen all use cap tubes. And R-22. There may be some
window units with other gasses, but I've not yet worked on one.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
.

Thanks. You can easily tell that I have not done any real work.
Just read some books. The books all have lots of information on
capillary tubes and I figured that window units would use the least
expensive thing.

Dan

Posted by on October 6, 2008, 1:49 pm

wrote:

>>I have a friend who has a cottage that has gas fireplace for heat.
>> The cottage was built as a beach house and probably is not well
>> insulated. The gas available is propane and propane now costs more
>> than resistive electric heating in the Pacific Northwest. And that is
>> without considering the efficiency of the gas fireplace. One
>> solution for her would be to replace the gas fireplace with a wood or
>> pellet stove. And that is probably her best choice, even though it
>> would require installing a new chimney ( the gas fireplace is vented
>> through the wall and the height is considerably below the roof top).
>> But she has decided against that.
>> If anyone built a heat pump that was just intended for heating ( that
>> is no way to use it for air conditioning ) that would work well.
>> There is no great need for air conditioning for a beach house on Puget
>> Sound. But I do not know of any.
>> So the question is what are the major differences between a window
>> heat pump and a window air conditioner? Besides the obvious things as
>> the reversing valves.
>> Could one buy a used window air conditioner and installing it
>> backwards be at all feasible. One would have to short out the
>> thermostat in the air conditioner and install a thermostat inside the
>> cottage wired to an outlet. And one might have to use a timer so it
>> would not run long enough to ice up the evaporator. And it would not
>> be useful when it was really cold. But there is a large portion of
>> the year where the temperature is about 50 to 55 F. Not comfortable
>> without some heat, but not a lot of heat needed.
>> Used air conditioners in the PNW are very cheap. In the range of $30
>> to $50 for a almost new 5000 btu to 10,000 btu window unit. Almost as
>> cheap as an electric resistance heater. So there is no concern about
>> having a guarantee.
>> Dan

>Do you want it cheap?? or do you want it right??

You have to ask ?

--
Click here every day to feed an animal that needs you today !!!
www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo online at www.pmilligan.net/palm/
Free 'People finder' program now at www.pmilligan.net/finder.htm

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Using an air conditioner as a heat pump - Page 2