Forced air vs baseboard water system in heating/cooling


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



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wrote:

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



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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:
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)

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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wrote:

EA-
I may be mistaken but I'm getting the vibe that you have pretty mcuh no idea what you;re talking about....

ah, that would be the water - air heater exchanger of which I spoke & the point at which condensation must be dealt with
I think you need to read my post more carefully
cheers Bob
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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.

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

But, difficult to install, and block a lot of wall space where furnature might go. I've mixed feelign on them, have baseboards in my (current) house, and like them, but also still like forced hot air.

Personally I'm not sure this is practical.

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wrote:

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 ears.
--
EA


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wrote:

It would seem to me you could probably install a zoned electrically controlled damper system in the existing forced air system a lot easier.
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wrote:

It would seem to me you could probably install a zoned electrically controlled damper system in the existing forced air system a lot easier. ======================================= 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, http://www.homecomfortzones.com .
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.
--
EA








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http://www.pbs.org/thisoldhouse/videos/viewer.php?playertype=quicktime ;speed20;mediatype=video;media=%2Fwgbh%2Fthisoldhouse%2Fforced-air-zones-320.mov%2C%2Fwgbh%2Fthisoldhouse%2Fforced-air-zones-320.wmv;version=1.0;basepath=%2Fthisoldhouse%2Fvideos%2Fviewer.php;item=forced-air-zones;prefchange=1
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.
--
EA

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Existential Angst wrote:

http://www.pbs.org/thisoldhouse/videos/viewer.php?playertype=quicktime ;speed20;mediatype=video;media=%2Fwgbh%2Fthisoldhouse%2Fforced-air-zones-320.mov%2C%2Fwgbh%2Fthisoldhouse%2Fforced-air-zones-320.wmv;version=1.0;basepath=%2Fthisoldhouse%2Fvideos%2Fviewer.php;item=forced-air-zones;prefchange=1
I suppose the tubing they install is "plenum rated".
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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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