Heat anitcipator adjustments


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Old 12-13-05, 02:05 PM
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Question Heat anitcipator adjustments

I have a Honeywell round style thermostat that has a heat anticipator setting. I have a Weil-McClain gas-fired steam boiler approx 25 years old. I have a one-pipe steam system. The furnace is definitely oversized. In my internet researches various sites mention the heat anticipator setting vis a vis short-cycling in overiszed boilers. I don't know that much about heating systems - but if I understand it correctly short-cycling is when a boiler comes on too often without producing enough heat, which I think mine does.

The Utica Boiler home site, under FAQ, recommends a heat anticipator setting of 1.2 for new steam boilers (which is the top of the scale on my thermostat)

Another heating site which carries Honeywell thermostats states that "The estimated setting for steam systems is the largest number on the heat anticipator scale".

A Honeywell product site, which gives instructions for installing the T87F, which is probably what I have, says to adjust the heat anticipator to match the current rating of the primary control. They then detail a procedure to set the anticipator using an ammeter. After this they state that a slightly higher setting to obtain longer burner on times(and fewer cycles per hour)may be desirable in systems such as a 1-pipe steam system. As an example they suggest moving the scale up from 4 to 4.5, 4.5 to 5 etc until the desired burner on time is obtained.

The present setting on my heat anticipator is about .3, on a scale that goes up to 1.2. This was set back 20 some years ago by the guy who put it in, who, though licensed, was just starting out and working for himself.

My first concern is whether I can adjust this setting up gradually without damaging the thermostat. One site mentioned that if you set it too low it might damage the thermostat. Honeywell is implying the setting is an electricity driven thing, but then states you can adjust it gradually upward. Other authorites are saying to put the heat anticipator setting right to the top of the scale for a one-pipe steam system.

Any advice on this would be appreciated. I know this post is already long, but my main motivation in trying to change the setting is to save gas without compromising the comfort level. Will a more ideal heat anticipator setting save fuel? I should also point out our temps are kept fairly cool, around 65 usually.
 
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Old 12-13-05, 05:58 PM
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why all of a sudden are you short cycling if you did not do anything different maybe the anticipator is burned out try to put a meter on it change the thermostat to be sure
 

Last edited by mattison; 12-14-05 at 03:53 AM. Reason: No need to quote entire post above.
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Old 12-13-05, 06:51 PM
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If your anticipator was burned out, your house would overheat and the boiler would not short cycle. You probably can't burn your anticipator out with the minimal current draw of your gas valve or aquastat. There would be no harm in moving it up the scale (down physically) slightly and waiting a few hours before making another adjustment. You will know when you have it set too high because the temperature in the room will begin to overshoot the thermostat setting.

Ken
 
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Old 12-13-05, 09:05 PM
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Thankyou for the replies.
 
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Old 12-14-05, 11:25 AM
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I am no plumber but I will share what my Honeywell manual says.It states that if you could not find the anticipator setting on your old thermostat,use the setting for your type of system shown below.

Steam 1.2 Heat anticipator setting
Hot water heat 0.8
High-efeciency warm air 0.8
Standard warm air 0.4
Electric heat 0.3

It also states to never adjust the anticipator below .3
 
 

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