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
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
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.
Large buildings use this system,<<<<<
Large building or building complexes often use chilled water to
"deliver cooling" (Ie remove heat)
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
My assessment ......not reasonable for a house.
On Mon, 26 Oct 2009 13:28:13 -0400, Existential Angst wrote:
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)
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?
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.
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
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
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
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
So condensate handling is a big issue.
On Mon, 26 Oct 2009 15:19:01 -0400, Existential Angst wrote:
Aha, yeah, that sounds close.
Where I grew up it was all stuff like this:
... 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)
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
Depends a *lot* on what type of baseboard heaters you have. Finned-tube
baseboard heaters don't seem to deliver nearly as much heat as the solid
cast-iron types. My house has a combination of both: mostly iron, and a few
finned-tube heaters in areas that were remodeled long after original
construction. The iron ones take longer to heat up -- but they also take a lot
longer to cool off, which makes for a much more even heat. I wouldn't trade
them. When we remodeled the kitchen a few years ago, I removed the finned-tube
heaters that someone had installed in the 1980s and replaced them with more
cast-iron units; the kitchen is now *much* more comfortable than it was.
I hope they are on different zones. Putting the two types together on the
same zone makes for poor temperature control for the reasons you state. The
CI does not need the circulator running as much once heated. I'm not sure
of the cost difference, but sometime in the 60's, the finned tube became
much more predominant. Wish I had the CI in my house.
I believe I have seen baseboard heating recessed into the ball/baseboard.
Altho this probably hinders the natural convection process that makes
baseboard heaters more effective.
Ultimately, Da Heating Bomb is radiant floor heating -- altho god help the
home-moaner if a leak is sprung.
And, not easily retrofitted.
And not cheap.
It seems like, from the responses here and elsewhere, that it simply is not
done residentially, even among the rich. Not sure, but that's the
impression I'm getting.
In the big complexes where they do run chilled water into fan units in apts,
I think they get away with this because 99.99% of the piping is vertical,
with just itty bitty Tee'd length of pipe going to the units, and then
condensate pans proly collect the small amount of condensate from these T's,
and dump it with the condensate from the coils/fins.
This would proly have to mimic'd pretty accurately in a home, and then only
in new construction.
But if there are secrets to doing this post-construction in homes, I'm all
It would seem to me you could probably install a zoned electrically
controlled damper system in the existing forced air system a lot
Ask this old house showed something just like this, except it was a
pneumatic balloon stuffed in each register, with a pyooter in the basement.
You would also need a temp sensor in each room. I think there is a short
video of this on either the PBS website or this old house, and you can read
the name of the company off a shot of the product -- oh yeah,
And yeah, def'ly cheaper, altho I'll bet the hcz solution will still leave
a home-moaner reaching for the prepH.
But, if I were doing it from scratch, I'll bet a baseboard HW system would
be about the same install price as forced air + the hcz damper ditty, AND
operating-wise, I'll bet the HW system is a lot more efficient -- right
away, you dispense with a 10+ A blower motor, and probably better heat
transfer from flame to water.
But that still leaves the A/C: forced air would kill both birds with one
stone. Altho, you proly should have separate registers for heat and A/C --
one low, one high.
But, mebbe chilled water in a house would not be so bad to install, if built
with the house. I think the strategy would have to be that 99.9% of the
piping would have to be vertical, ie, no horizontal runs from fan unit to
fan unit (room to room). Altho the fan units can be miserably expensive.
Sep. minisplits for each room would be perfect zoning, but not cheap either.
No cheap lunches, apparently.
A short video of the installation of zoning in an existing forced air
system. Perty neat.
I don't recall them actually discussing the temp sensor in each room, and
the wiring thereof, altho that part could be wireless.
< email@example.com> wrote in message
I suppose the tubing they install is "plenum rated".
You just answered your question. Chillers in homes are not so practical and
can be expensive to run, may need water treatment and testing. Running
baseboard through the house may be difficult now too, depending on layout
and design. PEX does make it much easier than copper or iron ipe though.
If you want to make radical changes, talk to a couple of local contractors
that can see what your needs are and what type of construction you have.
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