Subject: zoned AC and gas AC

From: [email-masked] (Keith Bauer)
Date: Fri, 2 Jun 1995 11:48:22 GMT

I too have seen recent ads in the New York area talking about newer designs
on gas fired absorption AC units.  The advantages are supposed to be lower
operating costs due to gas prices, and quiet operation.  It all sounds very
convincing IF ONLY the systems are reliable, easy to repair (anything
unusual is costly/difficult to repair), and above all WORK!  I would be
very interested in such a system if modern engineering overcomes these
obstacles.

On another topic, I love either baseboard or radiant (in floor) hot water
heat because it is very easy to put a thermostat in every room, thus 
allowing for personal tastes in heating.  Is there any practical way to
do the same for AC???  It appears that AC can only be handled by forced
air systems probably due mainly to the condensation problems.  It seems
that zoning a forced air system, whether it is AC or heating or both, just
isn't practical as the efficiency of the unit drops terribly when not
properly loaded.  Are there any professioanls out there with some input
on this?  Thus far the HVAC people I have spoken to basically say just
don't complicate your life with it.........but they said the same thing
about my zoned hot water system which has been running perfectly for years!

Keith Bauer  [email-masked]

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From: [email-masked] (David A. Jump)
Date: 2 Jun 1995 16:57:44 GMT

In article <[email-masked]>, [email-masked] (Keith Bauer) writes:
|>
|> On another topic, I love either baseboard or radiant (in floor) hot water
|> heat because it is very easy to put a thermostat in every room, thus 
|> allowing for personal tastes in heating.  Is there any practical way to
|> do the same for AC???  It appears that AC can only be handled by forced
|> air systems probably due mainly to the condensation problems.  It seems
|> that zoning a forced air system, whether it is AC or heating or both, just
|> isn't practical as the efficiency of the unit drops terribly when not
|> properly loaded.  Are there any professioanls out there with some input
|> on this?  Thus far the HVAC people I have spoken to basically say just
|> don't complicate your life with it.........but they said the same thing
|> about my zoned hot water system which has been running perfectly for years!
|> 

In regard to zoning a forced air system, the issue of efficiency dropping
when the unit isn't fully loaded can be (and has been in commercial buildings)
addressed by using variable volume systems.  In residences it may be possible
to use the newer high-SEER AC units (which have two speeds) together with
dampered duct systems effectively.

But there are alternatives to compressor cooling, one of which is radiant
cooling where cool water is circulated through pipes in the ceiling or
panels hanging from the ceiling.  The water is only a few degrees cooler
than room temperature, in order to avoid condensation.  They can be controlled
by individual room thermostats also.  Unfortunately, they're not practical
in single family houses, but are in commercial buildings.  

I can give you a reference on single family house alternatives to compressor
cooling, please email if you want it.

David
[email-masked]

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From: [email-masked] (Kevin R. Boyce)
Date: Fri, 02 Jun 1995 13:15:49 -0400

In article <[email-masked]>,

>very interested in such a system if modern engineering overcomes these

I want to see one with the absorption section preheated by solar
collectors.   I think non-focusing concentrators (which ought to be
dirt-cheap if made in quantity -- just extruded aluminum) can get up to
several hundred degrees; maybe the gas isn't even needed on sunny days. 
Could you do the absorption directly in the (rather long) pipes in the
solar collectors, or do you need better control over the liquid's surface
area?

I've always thought Solar-powered A/C made sense, from an energy-storage
standpoint.
-- 
Kevin           [email-masked]