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Heat Furnace thermostat schematic?

A 5 year old RiteTemp 8030 thermostat started mis-behaving the other day. It would go into a heat cycle and keep on going until the house is toasty warm. The only way to stop it is by disconnecting the power to it (remove the control unit from the wall wiring(or turn off AC power to the furnace). I bought a similar replacement unit at Home Depot (newer, model 8030C) and all is working fine now. The question is: I wonder if anyone here have a schematic for the 8030? I think that there is probably a power device that turns on an internal relay that is stuck in the "heat mode" when powered on. Setting the thermostat switch to off or cool has no effect. This unit uses 2 AA batteries for alternate power source, but replacing them with new ones have no effect.

Reply to
cmdrdata
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There may be a miniature relay in the unit that has a stuck contact. The only way to fix it, very temporariiy, is to beat it on a very hard surface in various orientations until the contact opens. But, it is likely to fail again in a short time, so just toss it unless you can find a replacement relay.

Reply to
hrhofmann

I don't think it is the relay (brand name MASSUSE type 4E-2L-3). When I measured/compared the DPDT contacts with the new one, it was in the same state while power is off. Don't not easily done with power on.

Reply to
cmdrdata

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quoted text -

No other suggstions - sorry

Reply to
hrhofmann

Sadly, five years is a long time for some of the more recently made stats. I would replace it and be done with it.

We are presently using a mid-line (now, top then) RobertShaw automatic set-back (heat-only) thermostat that is 20 years old. It has "Made in USA" on it - something that is a rarity now.

Peter Wieck Wyncote, PA

Reply to
pfjw

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