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From: 2141smh@aluxe.UUCP (henning)
Newsgroups: net.consumers
Subject: Re: Re: Furnace anticipator setting
Message-ID: <452@aluxe.UUCP>
Date: Sat, 20-Oct-84 21:26:14 EDT
Article-I.D.: aluxe.452
Posted: Sat Oct 20 21:26:14 1984
Date-Received: Sun, 21-Oct-84 15:34:38 EDT
References: <152@ssc-vax.UUCP>  <683@hound.UUCP>
Distribution: net.consumers
Organization: AT&T Bell Laboratories, Allentown, PA
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From the keys of Steve Henning, AT&T Bell Labs, Reading, PA aluxe!2141smh


> The efficiency of a furnace is not determined by heat transfer
> from the furnace to the house air, but by the fraction of the
> generated heat that goes (or doesn't go) up the chimney. To
> minimze the heat going up the chimney, one should keep the plenum
> as cool as possible, to maximize transfer to the plenum. (I hope
> plenum is the right term.) I believe rapid cycling would do the
> best job in this regard.

The same amount of heat goes up the chimney when the furnace is on, however
every time it shuts off a chunk of residual heat goes up the chimney.  The
more times it shuts off, the more residual heat goes up the chimney. Thus
the more it cycles the more you loose.  This assumes the on-time is the same.
This why automatic dampers are energy saving devices that you can buy.
They eliminate this "chunk".