Forced air vs baseboard water system in heating/cooling

Posted by Existential Angst on October 26, 2009, 1:28 pm

Awl --

My 1920's house has forced air, does a decent job heating, a middling job
cooling the house, but at great expense -- essentially no zoning in these
old houses. NYC area.

Baseboard hot water systems are great, as they can be infinitely zoned with
ease -- by their very design, in fact.

But what about using the same for air conditioning (:"chilled water")?
Large buildings use this system, and have internal plumbing for handling the
condensate -- which can overflow, btw, with disastrous apt. consequences.

Is this do-able, practical in a house? How would long-ish horizontal pipe
runs be handled? Just avoid? How to handle the condensate off vertical
pipes?

I realize pipe insulation would of course help, but maybe not insulating
the pipes and effectively catching the condensation would ultimately be more
effective, more sanitary? With the pipes themselves acting to help the
dehumidification process.

Just curious as to what I'd be looking at if I went this route.

The energy savings would be, in my case, substantial, but the installation
cost would also likely be substantial, at the least.
--
EA

Posted by DD_BobK on October 26, 2009, 1:43 pm

wrote:

> Awl --
> My 1920's house has forced air, does a decent job heating, a middling job
> cooling the house, but at great expense -- essentially no zoning in these
> old houses. =A0NYC area.
> Baseboard hot water systems are great, as they can be infinitely zoned wi=

> ease -- by their very design, in fact.
> But what about using the same for air conditioning (:"chilled water")?
> Large buildings use this system, and have internal plumbing for handling =

the

> condensate -- which can overflow, btw, with disastrous apt. consequences.
> Is this do-able, practical in a house? =A0How would long-ish horizontal p=

ipe

> runs be handled? =A0Just avoid? =A0How to handle the condensate off verti=

cal

> pipes?
> I realize pipe =A0insulation would of course help, but maybe not insulati=

> the pipes and effectively catching the condensation would ultimately be m=

ore

> effective, more sanitary? =A0With the pipes themselves acting to help the
> dehumidification process.
> Just curious as to what I'd be looking at if I went this route.
> The energy savings would be, in my case, substantial, but the installatio=

> cost would also likely be substantial, at the least.
> --
> EA

>>>>>>But what about using the same for air conditioning (:"chilled water")=

?
Large buildings use this system,<<<<<

Large building or building complexes often use chilled water to
"deliver cooling" (Ie remove heat)

BUT

the chilled water is, at some point, run through a water-air heat
exchanger with an attendant air handler to cool the air.

Typically, in an industrial app, the delivery & return chilled water
pipes are insulated to prevent condensation....with the condensation
being handed on the heat exchanger.

While generating heated water in a residential app is easy...chilled
water isnt as easy.

Baseboard hot water heat might be worth the retrofit costs (adding
this to an existing house could be a LOT of work) but I seriously
doubt that your chilled water concept will work or be worth the
cost. :(

My assessment ......not reasonable for a house.

cheers
Bob

Posted by Jules on October 26, 2009, 2:48 pm

On Mon, 26 Oct 2009 13:28:13 -0400, Existential Angst wrote:

> Baseboard hot water systems are great, as they can be infinitely zoned with
> ease -- by their very design, in fact.

I'm curious how well they perform vs. wall-mount radiator panels, though.
I grew up overseas with houses all fitted with the latter - my experience
of baseboard water-heat so far is that they all seem to take a lot longer
until the room *feels* warm. I assume it's because people tend to be at
"people height" and having the heat source right on the baseboard means it
takes a while before the benefit's really felt (we have electric
baseboards at our current house and they seem to give similar behavior)

> But what about using the same for air conditioning (:"chilled water")?
> Large buildings use this system, and have internal plumbing for handling
> the condensate -- which can overflow, btw, with disastrous apt.
> consequences.

Is a related problem to the above not going to happen - i.e. all the
cooled air will stay at the bottom of the room, with it still being hot at
the level where the occupants generally are?

My experience of AC has always been that it's ducted and blown upward -
without any kind of fan assist, maybe there's a "danger" that you'll just
end up expensively cooling everyone's feet?

> Is this do-able, practical in a house? How would long-ish horizontal
> pipe runs be handled? Just avoid? How to handle the condensate off
> vertical pipes?

I'm curious about that, too - mainly because the water from our well sits
at about 50F year-round, and in the hot months the condensation on the
basement pipe runs can get quite bad. Insulation would presumably hlp, but
only if it's "good enough" (as otherwise it'll turn into a moisture trap
and cause all sorts of issues).

Doubtless it's possible to buy pipe that has insulation bonded to it,
rather than doing it after the fact, and this would probably work well
for some kind of AC system.

> The energy savings would be, in my case, substantial, but the
> installation cost would also likely be substantial, at the least.

Personally I just open more windows when it gets hot - but it only gets up
to about 90F here, so I can appreciate it's a different matter in hotter
areas.

I would like to fit hot-water radiators here, but only if I can find
some wall ones rather than baseboard...

cheers

Jules

Posted by Existential Angst on October 26, 2009, 3:19 pm

> On Mon, 26 Oct 2009 13:28:13 -0400, Existential Angst wrote:

>> Baseboard hot water systems are great, as they can be infinitely zoned
>> with
>> ease -- by their very design, in fact.

> I'm curious how well they perform vs. wall-mount radiator panels, though.
> I grew up overseas with houses all fitted with the latter - my experience
> of baseboard water-heat so far is that they all seem to take a lot longer
> until the room *feels* warm. I assume it's because people tend to be at
> "people height" and having the heat source right on the baseboard means it
> takes a while before the benefit's really felt (we have electric
> baseboards at our current house and they seem to give similar behavior)

>> But what about using the same for air conditioning (:"chilled water")?
>> Large buildings use this system, and have internal plumbing for handling
>> the condensate -- which can overflow, btw, with disastrous apt.
>> consequences.

> Is a related problem to the above not going to happen - i.e. all the
> cooled air will stay at the bottom of the room, with it still being hot at
> the level where the occupants generally are?
> My experience of AC has always been that it's ducted and blown upward -
> without any kind of fan assist, maybe there's a "danger" that you'll just
> end up expensively cooling everyone's feet?

>> Is this do-able, practical in a house? How would long-ish horizontal
>> pipe runs be handled? Just avoid? How to handle the condensate off
>> vertical pipes?

> I'm curious about that, too - mainly because the water from our well sits
> at about 50F year-round, and in the hot months the condensation on the
> basement pipe runs can get quite bad. Insulation would presumably hlp, but
> only if it's "good enough" (as otherwise it'll turn into a moisture trap
> and cause all sorts of issues).
> Doubtless it's possible to buy pipe that has insulation bonded to it,
> rather than doing it after the fact, and this would probably work well
> for some kind of AC system.

>> The energy savings would be, in my case, substantial, but the
>> installation cost would also likely be substantial, at the least.

> Personally I just open more windows when it gets hot - but it only gets up
> to about 90F here, so I can appreciate it's a different matter in hotter
> areas.
> I would like to fit hot-water radiators here, but only if I can find
> some wall ones rather than baseboard...

Indeed, I mis-spoke.

Altho I indeed said "baseboard", thinking more of the pipes themselves, I
mean these highly finned units, about the size of suitcases, that blow up
and out, at about 45 deg -- altho for the heat they probably should blow
*down* about 45 deg. Perhaps what you meant by "wall radiator panels".

But at any rate, these units are not cheap, either. These units, Trane,
that I priced over 10 years ago, were $1400 *each*. goodgawd....
And really nothing more than finned coils with a speed fan and an off
position!
But very quiet.

And to respond to Bob, the chilled water is not used in an air-exchange
system, with air being delivered, but the water actually piped to the
buildings and to these room units, where a fan then makes the thermal
exchange with the room air.

In large complexes, the "condensers" for these units are actually huge
evaporative cooling towers, the size of whole buildings themselves, with the
refrigerant often being something like lithium bromide in very large
"absorption chillers".
But the condensing process is not the issue here, as many different types of
water chilling systems can be used, with the chilled water piped directly
into the living units.

Thus, a substantial issue with condensation, which, as I mentioned before,
has been knowd to flood out apartments.
I think I calculated once that a residential 5 ton unit (60,000 btu's), on a
suff'ly humid hot day, can fill a 55 gal drum, or perhaps even quite a bit
more.

So condensate handling is a big issue.
--
EA

> cheers
> Jules
>

Posted by Jules on October 26, 2009, 6:36 pm

On Mon, 26 Oct 2009 15:19:01 -0400, Existential Angst wrote:

> Altho I indeed said "baseboard", thinking more of the pipes themselves,
> I mean these highly finned units, about the size of suitcases, that blow
> up and out, at about 45 deg -- altho for the heat they probably should
> blow *down* about 45 deg. Perhaps what you meant by "wall radiator
> panels".

Aha, yeah, that sounds close.

Where I grew up it was all stuff like this:

http://www.designer-warmth-radiators.co.uk/images3/stelrad-softline-radiator.jpg

... but I don't think what you describe is that different, at least in
terms of size (and probably heat output - although the fin arrangement
sounds like a bit of a dust magnet).

All the DIY stores where I am these days (northern US) seem to sell the
"baseboard" water heaters that are finned, but only sit about 8" off the
floor - and I'm not sure they get heat to where it's really needed quickly.

(In the spirit of DIY I'd be tempted to make something, but it'd be a heck
of a lot of pipework per rad :-)

I've also seen big cast iron rads all over the world, but I don't think
they've been made new for 50 years or more. I think the main issue with
those was corrosion though (and "start-up" time as there was so much metal
to them that they'd take a while before they produced useful heat)

> But at any rate, these units are not cheap, either. These units, Trane,
> that I priced over 10 years ago, were $1400 *each*. goodgawd.... And
> really nothing more than finned coils with a speed fan and an off
> position!

Aha - interesting. So the ones you're thinking of do have a fan...

Good luck in getting a solution, anyway - I'll keep reading with interest
:-)

cheers!

Jules

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