forced-hot-air vs baseboard heating: is it really "drier" heat?
Meir Laker
opposed to forced-hot-air heating.
The reason: "conventional" wisdom has it that baseboard heating dries
out a house less than forced-hot-air heating, significantly less so
that a humidifier is not needed (besides the fact that a humidifier
could not be installed without duct work).
Is this true?
I have always thought that the main source of winter dryness is the
difference in relative humidity between the outside cold air and the
inside warm air. If so, it would seem to me irrelevant how the air is
heated. (A rise in temparature from 20 degrees to 70 degrees is going
to cause the relative humidity to drop the same amount no matter the
source of the heat.)
If so, it would seem to make more sense installing forced-hot-air
heating and adding a humidifier.
Meir Laker
IBM Thomas J. Watson Research Center
P.O. Box 218, Yorktown Heights, NY 10598
Phone: 914-945-2699
--
Meir Laker
IBM Thomas J. Watson Research Center
P.O. Box 218, Yorktown Heights, NY 10598
Phone: 914-945-2699
Tieline: 862-2699
Meir Laker
patterson,george r
>New construction in our area seems to have baseboard heating as
>opposed to forced-hot-air heating.
>
>The reason: "conventional" wisdom has it that baseboard heating dries
>out a house less than forced-hot-air heating, significantly less so
>that a humidifier is not needed (besides the fact that a humidifier
>could not be installed without duct work).
>
>Is this true?
I grew up in a house with electric baseboard heaters. As I recall, the
house didn't noticeably dry out in winter at all. I now live in a house
equipped with gas forced air with the smallest plenum mounted humidifier
Home Depot sells. There are noticeable problems; excessive evaporation
from my aquarium, sinus troubles, "cottonmouth" in the mornings, etc.
This is despite the fact that New Jersey (my current location) is more
humid than the area in which I grew up.
I can't say why, but "conventional" wisdom is no less wisdom for being
conventional. Sometimes "old wives" are pretty smart.
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Carl Heinzl
>>The reason: "conventional" wisdom has it that baseboard heating dries
>>out a house less than forced-hot-air heating, significantly less so
>>that a humidifier is not needed (besides the fact that a humidifier
>>could not be installed without duct work).
>>
>>Is this true?
>I grew up in a house with electric baseboard heaters. As I recall, the
>house didn't noticeably dry out in winter at all. I now live in a house
>equipped with gas forced air with the smallest plenum mounted humidifier
>Home Depot sells. There are noticeable problems; excessive evaporation
>from my aquarium, sinus troubles, "cottonmouth" in the mornings, etc.
>This is despite the fact that New Jersey (my current location) is more
>humid than the area in which I grew up.
>I can't say why, but "conventional" wisdom is no less wisdom for being
>conventional. Sometimes "old wives" are pretty smart.
I don't know what conventional wisdom the original poster was talking
about but I have to agree 100% with George. We recently (well,
actually 4 years ago) had our house changed from forced hot air (by
oil - goodbye to the 275 gallon oil tank and sending all our money to
the mideast) to forced hot water (by gas - hello to a much cleaner
burning and space saving fuel).
We still have to run a humidifier a little in the winter but not
nearly as much as we did when we had the forced hot air. Also, the
forced hot air was not nearly as good at keeping a constant
temperature in a room. There were many more hot and cold spots. With
the forced hot water each room is much more at thermanl equilibrium
(well, as much as it will get anyway).
-Carl-
--
Tom Vervaeke
in Colorado which is a fairly dry state - as far as humidity goes. We
decided on hot-water baseboard heated by a natural-gas boiler. Here' the
good points:
1. very quiet. You can barely here the boiler and the little pump that
moves the water.
2. pretty cheap to operate.
3. clean, no frills.
4. Allows for as many heating zones as you like. We have 10. While
zoning can be accomplished with forced air, it is difficult to do.
Good luck.
( ___ )------------------------------------------------------------( ___ )
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Meir Laker
Date: 24 Nov 92 16:25:55 GMT
>>The reason: "conventional" wisdom has it that baseboard heating dries
>>out a house less than forced-hot-air heating, significantly less so
>>that a humidifier is not needed (besides the fact that a humidifier
>>could not be installed without duct work).
>>
>>Is this true?
Someone sent me email note suggesting the reason that the hot water
baseboard is less drying is because it actually leaks water vapor.
Anyone heard this explanation before?
We still have to run a humidifier a little in the winter but not
nearly as much as we did when we had the forced hot air.
Do you have a small table-top ultrasonic or do you need a large
console type for the house? (Since you have no ducts, you can't have a
furnace mounted unit.) If you used to have a furnace mounted unit,
isn't now a pain to have to constantly fill a small unit by hand.
Plus, the console units are rather noisy.
Also, the forced hot air was not nearly as good at keeping a
constant temperature in a room. There were many more hot and cold
spots. With the forced hot water each room is much more at
thermanl equilibrium (well, as much as it will get anyway).
Is it possible that the original forced air didn't have the enough
vents in some rooms, resulting in cold spots, whereas you made sure
with the new system to increase the capacity in previously cold areas?
Steven Bellovin
> constant temperature in a room. There were many more hot and cold
> spots. With the forced hot water each room is much more at
> thermanl equilibrium (well, as much as it will get anyway).
On the other hand, forced air is (generally) much better at heating a
house quickly -- useful if you use non-intelligent setback thermostats.
(With the smart ones, in which you program a time/desired temperature
pair, that's less important.)
Meir Laker
Date: 25 Nov 92 13:03:45 GMT
How do the smart ones work? Do they "learn" the characteristics of the
room over time so that they "know" how much in advance is enough to
heat a given room to the desired temperature?
Sounds a bit hard to me. If so, the "dumb" setback thermostats allow
ME to use MY intelligence to start up at exactly when I think it needs
to start to warm the temperature to my desired target by the time I
want. I can fine-tune this for weather changes,etc.
Steven Bellovin
> How do the smart ones work? Do they "learn" the characteristics of the
> room over time so that they "know" how much in advance is enough to
> heat a given room to the desired temperature?
>
> Sounds a bit hard to me. If so, the "dumb" setback thermostats allow
> ME to use MY intelligence to start up at exactly when I think it needs
> to start to warm the temperature to my desired target by the time I
> want. I can fine-tune this for weather changes,etc.
I don't know for sure how they work. I assume they guess at the outside
temperature by looking at how fast the temperature drops during setback
periods. By watching how fast the temperature rises for a given outside
temperature, it can learn how fast things warm up under different conditions.
With those two pieces of information, I doubt that it's that hard for
it to approximate when to turn on the furnace. I suppose that fancier
models might even incorporate time-of-day models -- the temperature will
generally drop faster at 2am than at 2pm.
As for changing the start times on the manual ones -- to me, that sounds
very unpleasant. Certainly, on many thermostats changing any aspect of
the programming is not particularly convenient. Nor need it be; it's
not a frequent operation. (On our old mechanical setback thermostat,
one had to move some tiny pins that were (a) plastic, and always threatening
to break, it seemed, and (b) were hard to extract and insert.
Besides -- I'd rarely remember to do it, especially when the weather
changes suddenly (as it's been doing around here of late), or when
the forecast is wrong. And do you really know what time to turn on
the thermostat for different forecasts? I sure don't.
Dan Craft
Laker) writes:
> How do the smart [set-back thermostats] work? Do they "learn" the
> is enough to heat a given room to the desired temperature?
I just had a forced-air system installed with a digital set-back thermometer
with an "Energy Management System" feature (a White-Rogers thermostat which
looked a lot like others I've seen sold under different names). The operation
manual espoused about its wonderful ability to determine when to start heating
to reach the desired temperature at the specified time.
Then I grabbed a peak at the installation manual while the installer was
working on something else. It said that this feature simply allows 15 mins for
every 2 degrees (F) which it will need to raise the temperature. The marketing
hype certainly conjured up something more grand.
--Dan Craft <DCr...@MV.US.Adobe.com>
Deepak S. Gianchandani
> Date: 25 Nov 92 13:03:45 GMT
>
> > Also, the forced hot air was not nearly as good at keeping a
> > constant temperature in a room. There were many more hot and cold
> > spots. With the forced hot water each room is much more at
> > thermanl equilibrium (well, as much as it will get anyway).
>
> On the other hand, forced air is (generally) much better at heating a
> house quickly -- useful if you use non-intelligent setback thermostats.
> (With the smart ones, in which you program a time/desired temperature
> pair, that's less important.)
>
>
I have in my house a Forced Air, GAS Burner, and I get No savings
(actually it costs more) if I lower and raise the thermostat,
rather then leaving at 68 F. At my parents home, we have a Baseboard,
Oil Furnance. And we saved money by turning the Thermostat down when
going to work/school and then rasining it back up to 70F when back in home,
and then lowering it to 64 F at night when going to sleep.
I tried doing the same thing with the Forced Air, GAS Burner
and I saw no savings. Note: Our Gas and electric company gives a summary
report of how much btu's used this month, perivous two month, plus
Last year's btu's used and the average temperature last year months,
along with this months average temp.
Going back to where I started, when I lowered and raised the
Termostat, the Forced air system stays on longer to get to the
temprature required and cycle more often to maintain the temperature
(remember Heating is Passive, i.e. radiant -- we heat the air, which
heats the bed, room, sofa's, etc.). With the Baseboard, the first
cycle of Oil Furnace would be longer, but after that it would come
back to normal. The pricipal in the Hot Water Baseboard was different.
The water in the Baseboard would circulate until it reached its low
level cold point, say 140F, as soon as the water temprature reached
this, the circulator pump would turn off, the Furnace would already
have fired as the temperature is below its differential point, say of
10F, and fire up to your high point, say of 160F, and go off.
At 160F the circulator pump would turn on again, and the cycle would
repeat until the tempature set at the Room Thermostat was satisfied.
From my experience, as far as saving money on Heating bill, by
lowering and raising temp. I find Baseboard heat better. The
disadvantage in Baseboard heat is that you need an external way of
providing Humidity in the House. The Forced Air system allows for
attachements to be added, easily, to make up for the humidity loss.
--
____________________ . . __ . | Deepak S. Gianchandani
\___________________|) .____.--"--"---._____ | E-mail:gi...@opencon.com
. || /_____/ NCC_1701 __/ . . . |
. . || /--/--._________.----/ . | To Boldly Go Where
Meir Laker
Date: Wed, 2 Dec 1992 23:20:01 GMT
The disadvantage in Baseboard heat is that you need an external way
of providing Humidity in the House. The Forced Air system allows
for attachements to be added, easily, to make up for the humidity
loss.
This brings us back to my original posted question: "Conventional
wisdom", with additional testimony from "the net", claims that
baseboard heating is less drying and generally needs no additional
humidification. I questioned the rationale: the relative humidity
level of the house should drop the same when the house temperature is
higher that than the outside temperature no matter how it is heated -
baseboard of forced air.
Do you have a stand-alone humidifier? What about a stand-alone air
cleaner?
Erwin Schroeder
>level of the house should drop the same when the house temperature is
>higher that than the outside temperature no matter how it is heated -
>baseboard of forced air.
>
seems inescapable. Also, we are told that just living in a house
produces a lot of humidity from cooking, breathing, showers, etc., so
some of the moisture must be somehow leaving.
My conjecture is that the forced air system with its neccessary pressure
differentials to force air movement, also forces air from leaky joints
in the duct work into attics, walls and other places where it is
eventually forced out of the house. (Just look at the joints in sheet
metal ducts; sometimes you can see through them.) Also because of
the pressure differentials, heated rooms will be at a higher pressure
than the room containing the blower, so that air will be forced out at
one place and drawn in at the other around windows, doors, light
fixtures, etc.
Erv
--
steven.a.zubatkin
Uh?
The explanation of why forced air heat is "drier" than baseboard heat
that I've heard is the following:
A forced air system recirculates and heats the same air over and over
again. Each time this air is heated, some humidity is lost (up the
chimney?). Heating the same air with baseboard heat does not allow
the humidity to escape.
Does this make sense?
Steve
PB Schechter
>From article <28...@oasys.dt.navy.mil>, by schr...@oasys.dt.navy.mil (Erwin Schroeder):
<much deleted>
>
>Uh?
>
>The explanation of why forced air heat is "drier" than baseboard heat
>that I've heard is the following:
>
>A forced air system recirculates and heats the same air over and over
>again. Each time this air is heated, some humidity is lost (up the
>chimney?). Heating the same air with baseboard heat does not allow
>the humidity to escape.
>
>Does this make sense?
>
>Steve
Well, I don't think it makes sense in a well designed forced air
system, at least. Forced air heating systems are "closed": the air that
gets heated (and that circulates through the house) is separated from the
combustion chamber by the heat exchanger (that's why a cracked heat
exchanger is dangerous: it allows combustion gas into the house air
supply and vice versa). So, while the same air gets heated over and
over again, its humidity doesn't get out of the house any faster than an
equally tight (or loose, as the case may be) house that uses some other
type of heat.
The reason for the qualification "well designed" in my first sentence
is that not all forced air systems get combustion air from outside. In
one that does *not*, inside--relatively humid--air will end up in the
furnace's combustion chanber, and outside--relatively dry--air will be
drawn into the house via whatever leaks there are in the house, to replace
the inside air that goes up the chimney.
So, it seems to me that it makes sense for forced air heat to be drier
than radiant heat if the former gets its combustion air from inside, but
I don't see why it should be if it uses outside combustion air.
PB Schechter
p...@cs.du.edu
Douglas S. Rand
|> The explanation of why forced air heat is "drier" than baseboard heat
|> that I've heard is the following:
|>
|> A forced air system recirculates and heats the same air over and over
|> again. Each time this air is heated, some humidity is lost (up the
|> chimney?). Heating the same air with baseboard heat does not allow
|> the humidity to escape.
|>
|> Does this make sense?
No. There is no humidity lost when heating air, although the
relative humidity of warm air *is* lower than colder air. I think
there is no difference. I grew up in a house with forced hot
water. The winters were very dry, I remember the static buildup
on blankets and such. I don't think my current house with
forced hot air is all that different.
The air that goes up the chimney is the combustion gas, and this
will be there for either system.
--
Douglas S. Rand <dr...@osf.org> OSF/Motif Dev.
Snail: 11 Cambridge Center, Cambridge, MA 02142
Disclaimer: I don't know if OSF agrees with me... let's vote on it.
Amateur Radio: KC1KJ
Edgar_Circenis
> In article <1992Dec7.1...@cbfsb.cb.att.com> ste...@cbnewsb.cb.att.com (steven.a.zubatkin) writes:
> >From article <28...@oasys.dt.navy.mil>, by schr...@oasys.dt.navy.mil (Erwin Schroeder):
> >again. Each time this air is heated, some humidity is lost (up the
> >chimney?). Heating the same air with baseboard heat does not allow
> >the humidity to escape.
>
> gets heated (and that circulates through the house) is separated from the
> combustion chamber by the heat exchanger
> over again, its humidity doesn't get out of the house any faster than an
> equally tight (or loose, as the case may be) house that uses some other
> type of heat.
>
> The reason for the qualification "well designed" in my first sentence
> is that not all forced air systems get combustion air from outside. In
> one that does *not*, inside--relatively humid--air will end up in the
> furnace's combustion chanber, and outside--relatively dry--air will be
> drawn into the house via whatever leaks there are in the house, to replace
> the inside air that goes up the chimney.
>
> So, it seems to me that it makes sense for forced air heat to be drier
> than radiant heat if the former gets its combustion air from inside, but
> I don't see why it should be if it uses outside combustion air.
There are two types of heating systems: those which burn fuel inside
the house to create heat (gas forced air, gas water heater, wood, coal,
oil, etc) and those which do not (electric heat, electric water, solar, etc).
Whether you get combustion air directly from the outside or not doesn't
really matter. As long as combustion gases are going up the chimeny, they
will be replaced by air from outside the house (either via a fresh air
inlet, or through cracks around doors, windows, etc), thus lowering the
humidity inside the house.
If you use electricity or solar power to provide heat for your house,
there will be less air flow between the outside and inside of the house.
Edgar "possibly wrong, but it sounds good anyway" Circenis
Topher Eliot
|> >> I questioned the rationale: the relative humidity
|> >>level of the house should drop the same when the house temperature is
|> >>higher that than the outside temperature no matter how it is heated -
|> >>baseboard of forced air.
|> >>
|> that I've heard is the following:
|>
|> A forced air system recirculates and heats the same air over and over
|> again. Each time this air is heated, some humidity is lost (up the
|> chimney?).
likely to get carbon monoxide in as you are to put humidity out.
--
Topher Eliot Data General DG/UX Systems Administration Development
(919) 248-6371 el...@dg-rtp.dg.com
Obviously, I speak for myself, not for DG.
misc.consumers.house archivist. Send mail to house-...@dg-rtp.dg.com
"I can understand Teenage Mutant Ninja Turtles, but I can't understand mutually
recursive inline functions." --anon.
Douglas S. Rand
|> ...
|> The reason for the qualification "well designed" in my first sentence
|> is that not all forced air systems get combustion air from outside. In
|> one that does *not*, inside--relatively humid--air will end up in the
|> furnace's combustion chanber, and outside--relatively dry--air will be
|> drawn into the house via whatever leaks there are in the house, to replace
|> the inside air that goes up the chimney.
|>
|> So, it seems to me that it makes sense for forced air heat to be drier
|> than radiant heat if the former gets its combustion air from inside, but
|> I don't see why it should be if it uses outside combustion air.
Sigh. You mean just like a well designed or not well designed
forced hot water system that uses or doesn't use outside air
for combustion? This is not any different.
Deepak S. Gianchandani
First, An earlier poster had asked if we have an external
humidifier, the answer is YES. The second question was an Air
cleaner, NO.
(I was the one who stated that "forced" air is drier and a
humidifier can be added easily to forced air systems than
baseboard systems).
In the forced air gas system I have, I don't see another place
where the gas burner is beining suuplied from outside air. Just the
other day I was changing air filters on it and I didn't notice
anyting. I even turned the furance on, while it was open, (overriding
the safety switch), I needed to see how fast was the air flow and the
direction so to make sure that I'm replacing the air filter correctly.
I could be wrong, I'm no expert on these systems, but I did not see
any fresh "outside air" getting into it.
The same goes for the Water Heater, which is Next to the furnace,
I saw a flute going out for combustion air, but nothing to provide
addition air in the fireing area. Is the pipe divided, one side for
input one for output ?.
Also, my parents house is baseboard, oil heat, and in the
winter it to would get dry (winter in New Jersey, on some days is very
dry, humidity less than 30%), and as I stated earlier we would have an
external humidifier to suppliment the air.
Don Perley
The reason for the qualification "well designed" in my first sentence
is that not all forced air systems get combustion air from outside. In
one that does *not*, inside--relatively humid--air will end up in the
furnace's combustion chanber, and outside--relatively dry--air will be
drawn into the house via whatever leaks there are in the house, to replace
the inside air that goes up the chimney.
So, it seems to me that it makes sense for forced air heat to be drier
than radiant heat if the former gets its combustion air from inside, but
I don't see why it should be if it uses outside combustion air.
So you don't think that the boiler for the hot water heat uses air for
combustion? NOT
-don perley
per...@balltown.cma.com