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I have a honeywell mercury switch thermostat when turned down to 60 degrees still calls for heat? The current temperature is 72 degrees even when turned down. Do the older style thermostats have a way to trouble shoot them?

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Are you sure it is calling for heat?  Disconnect the stat and see if you still have system operation (Be careful if this is a line voltage unit).  If so, the stat is not bad, there is a problem with the relay or with the wiring to it.  If not, there is probably a short in the anticipator within the stat.  This is a heating coil which helps the unit figure out how much heat 'will' be coming when the contacts close. This cannot be repaired.  
If you have a line voltage system, you can still obtain thermostats which run on them.  The better option is to put in a 24v relay system.  You can get advice on how to do that at any home store....about 30-40 dollars and then get one of the new programmable stats.  This will save energy and be more accurate. An energy star unit is a better bet anyway, it will save its cost in about a year. 

Posted on Nov 23, 2008

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