From: patter@dasher.uucp (24224-guthrie)
Subject: Re: Humidifier questions
Organization: Bellcore, Livingston, NJ
Date: Sat, 10 Oct 92 03:11:45 GMT

In article <3877@ecicrl.ocunix.on.ca> clewis@ferret.ocunix.on.ca (Chris Lewis) writes:

>Incidentally, according to one book I read, the size hole the
>manufacturers recommend that you have to cut in the furnace outlet
>is much too large, and causes a considerable proportion of the heat
>to recirculate, and you lose a lot of air pressure - screwing up
>heat flow balance in the house.  The book recommended leaving the hole
>around 2" - the humidifier will still work fine, but the furnace will
>be operating more efficiently.

The hole may be too large, but the rest of the argument is nonsense -
at least with my unit. First off, my humidifier has a plate which may
be shifted across the air return line to restrict the amount of air
flowing through the unit to whatever extent I like (even completely
off). I currently have it wide open and have noticed no difference
in the force of air being discharged (I had this valve closed at one
time). There may *be* a difference, but it's not noticeable.

My unit has flow valves on every duct, so the house can be balanced
(and probably is) for use with the humidifier.

As to the recirculation of air reducing the efficiency, my unit has 
a fan control with upper and lower plenum heat settings. Since the
unit was installed in 1954, I think this isn't new technology. When
the thermostat in the house cuts the unit on, the burners light up,
but the fan doesn't start up. When the temperature in the plenum passes
120 degrees, the fan goes on. When the temperature in the plenum passes
180 degrees, the burner shuts off. When the temp drops past 120 again,
the fan shuts off.

With the bypassing of heated air back into the return air duct, the
plenum will warm faster, causing the fire to go out sooner, using
less gas. The only effect I can think this might have is to cause
the unit to come on more frequently and stay on for shorter periods
of time. I *have* noticed this phenomena.

When I bought my house, the humidifier was gutted, so I closed it up.
It went through three seasons like that, and then bought a replacement.
I've put one season on it. Comparison of the heating bills (both gas
and electric) for months with similar average temperatures in 1991
(humidfier ducts closed) and 1992 (humidfier installed) show no
consistent difference in cost.

>Some people may warn you about water getting into the furnace and
>causing premature rusting.  We had one, and didn't notice any such
>problems - even when the humidifier was tied into the duct such that
>the humid air went through an electrostatic filter.  Just have to
>make sure that the thing is set up properly and doesn't leak.

I haven't had this problem either. Of course, I have no idea how long
the original humidifier actually operated, and the new one is only in
its second season.

>Remember to shut down the water, and empty the tray when you don't
>need it.

Yeah. The last time I did that, we had a mid-summer cold snap two days
later. Easiest way to save on air conditioning I know of - shut down
the heater!

patter@dasher.cc.bellcore.com
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                    |
George Patterson -  | No city is large enough to support one lawyer
                    | No town is too small to support two.
                    |                        Samuel Clemens
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Newsgroups: misc.consumers.house