Re: really quiet central AC/dehumidifier?

Posted by Graven Water on June 25, 2008, 11:15 am

I get the impression, reading around, that a central AC can't dehumidify
without cooling, because the condenser, which is what would heat
the air in a dehumidifier, is outside, being cooled by outside air.

It should be possible to expose the condenser to outside air or
to the inside air, depending on whether you want just dehumidification,
which would heat the air, or air conditioning. So I don't know why a
central AC couldn't also be a dehumidifier. It would have to have a
humidity sensor of course. For my purposes it'd have to be able to reduce
the humidity to 50%.

Laura

Posted by Noon-Air on June 25, 2008, 11:44 am

>I get the impression, reading around, that a central AC can't dehumidify
> without cooling, because the condenser, which is what would heat
> the air in a dehumidifier, is outside, being cooled by outside air.
> It should be possible to expose the condenser to outside air or
> to the inside air, depending on whether you want just dehumidification,
> which would heat the air, or air conditioning. So I don't know why a
> central AC couldn't also be a dehumidifier. It would have to have a
> humidity sensor of course. For my purposes it'd have to be able to reduce
> the humidity to 50%.
> Laura

A *competent* HVAC tech would have already explained all that to you, and
would have built in humidity controls as a standard offering. Keep in mind
that on most normal resi installations, if the system is designed, sized,
and installed correctly, it will have no problem maintaining 75 degrees with
50% humidity.

Posted by Stormin Mormon on June 25, 2008, 12:17 pm

That would be a ductwork nightmare. I've heard of systems that can run AC to
get the humidity percentage, and then run the furnace as needed, to keep the
temp from being too cold. That's wasteful, of course.

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

I get the impression, reading around, that a central AC can't dehumidify
without cooling, because the condenser, which is what would heat
the air in a dehumidifier, is outside, being cooled by outside air.

It should be possible to expose the condenser to outside air or
to the inside air, depending on whether you want just dehumidification,
which would heat the air, or air conditioning. So I don't know why a
central AC couldn't also be a dehumidifier. It would have to have a
humidity sensor of course. For my purposes it'd have to be able to reduce
the humidity to 50%.

Laura

Posted by Zyp on June 27, 2008, 10:14 pm

Stormin Mormon wrote:

> That would be a ductwork nightmare. I've heard of systems that can
> run AC to get the humidity percentage, and then run the furnace as
> needed, to keep the temp from being too cold. That's wasteful, of
> course.
> --
> Christopher A. Young
> Learn more about Jesus
> www.lds.org
> .
> I get the impression, reading around, that a central AC can't
> dehumidify without cooling, because the condenser, which is what
> would heat
> the air in a dehumidifier, is outside, being cooled by outside air.
> It should be possible to expose the condenser to outside air or
> to the inside air, depending on whether you want just
> dehumidification, which would heat the air, or air conditioning. So
> I don't know why a central AC couldn't also be a dehumidifier. It
> would have to have a humidity sensor of course. For my purposes it'd
> have to be able to reduce the humidity to 50%.
> Laura

What are you talking about Stormin? What would be a duct work nightmare?

To be quite frank [honest] a reputable refrigeration tech could easily build
a add on to your system, but running a third pipe, bringing hot gas to a
indoor coil that is installed after the evaporator. The subsequent liquid
discharge from the reheat coil could be piped [using a check valve] directly
to the indoor evaporator metering device, the suction would remain going to
the outdoor condenser / compressor section with a solenoid valve that could
change the hot gas direction from the outdoor condenser coil to the indoor
reheat coil.

The only problem, is you would have more heat coming into the home than is
being removed, but the result is dehumidified air. Using a P/E chart, the
difference would be the heat of compression [and added electrical heat from
the compressor] would be added to the air as it left the system. Eventually
the system would have to change over to nominal air conditioning to 'remove'
the added heat, and then could [if the humidistat is not satisfied] return
to dehumidification.

Get your credit card out though.

--
Zyp

Posted by Stormin Mormon on June 27, 2008, 10:29 pm

I was getting visions of ducting the indoor air to the condensor, and then
the hot blast from the condensor into the house.

The condensor in the duct work could be done. If there was some kind of
thermostat and a variation on a heat pump reversing valve. Divert the heat
into the air stream when the house needed the heat. I've never seen one, but
it sure seems possible. Great idea, chief.

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

What are you talking about Stormin? What would be a duct work nightmare?

To be quite frank [honest] a reputable refrigeration tech could easily build
a add on to your system, but running a third pipe, bringing hot gas to a
indoor coil that is installed after the evaporator. The subsequent liquid
discharge from the reheat coil could be piped [using a check valve] directly
to the indoor evaporator metering device, the suction would remain going to
the outdoor condenser / compressor section with a solenoid valve that could
change the hot gas direction from the outdoor condenser coil to the indoor
reheat coil.

The only problem, is you would have more heat coming into the home than is
being removed, but the result is dehumidified air. Using a P/E chart, the
difference would be the heat of compression [and added electrical heat from
the compressor] would be added to the air as it left the system. Eventually
the system would have to change over to nominal air conditioning to 'remove'
the added heat, and then could [if the humidistat is not satisfied] return
to dehumidification.

Get your credit card out though.

--
Zyp

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