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From: dwl@hou4b.UUCP
Newsgroups: net.consumers,net.misc
Subject: Re: Furnace anticipator setting
Message-ID: <1187@hou4b.UUCP>
Date: Thu, 18-Oct-84 17:08:07 EDT
Article-I.D.: hou4b.1187
Posted: Thu Oct 18 17:08:07 1984
Date-Received: Sun, 21-Oct-84 09:47:21 EDT
References: <152@ssc-vax.UUCP>
Organization: AT&T Information Systems Laboratories, Holmdel, NJ
Lines: 27

Maximum efficiency (minimum fuel for a given indoor average
temperature) is reached with long on-time duty cycles.  This is
because the furnace gets the opportunity to run at maximum
temperature, where maximum heat transfer occurs.  It's internal
limit switch should be set to keep it from getting hotter than that
temperature. As the original news item pointed out, rapid cycling
produces the most uniform temperature (minimum deviation from
average) which is probably the most comfortable. It "correct"
anticipator setting will therefore be a compromise between comfort
and efficiency.  In general, the thermostat manufacturer's
recommended compromise setting can be obtained by setting the
anticipator control to the number (in milliamps, usually)
corresponding to the current rating of your gas control valve.
Starting with this setting, vary it a little at a time to find
comfort, if the original setting is not comfortable.

The anticipator is there because your furnace keeps producing heat
after the thermostat opens.  The anticipator causes the thermostat
to open a little before the temperature increases to the set point,
in "anticipation" of the continued furnace output.  If you have a
very old or a very large furnace (lots of iron) you will probably
need to set the anticipator to a lower number of amperes, so that it
will anticipate more than average thermal inertia.

-Dave Levenson
AT&T-ISL
Holmdel