Rudd Fan Thermostat

[Burhans]

All, I was having problems with my Furnace Fan staying on after the heat was finished blowing. I thought it was something with the furnace but after inspecting the Original Thermostat I noticed two mercury vials. The top one controls the fan and the bottom one controls the Heating/Cooling. When the Heat would kick off the mercury would move to the other side of the vial but the top mercury vial controlling the fan would not move to the other side for minutes to hours and sometimes all night long. Can I fix this or do I have to replace the 1988 Original RUDD thermostat.

Thanks, Everett

[AutoTracer]

That is the way the thermostat should work. You should upgrade to electronic though. They are cheap and often have rebates from the utility. They alsm do make a house more even temperatured. Sometimes a thermostat has a seperate fan switch but that is a differtent function to turn on the fan regardless of heat demand.

It sounds like your problem (if there is a problem) is in the furnace. There is a thermostat inside that senses the temp of the fire box. When it reaches a high on temp it starts the fan and when it reaches a lower off temp it turns it off. The thermostat controls the fire which heats the firebox but the fan is controlled seperately inside the furnace. (this is why you may hear the fire run for a minute or tweo before the fan comes on) If the difference between the on and off temps is not large enough or if the sensor is defective, the fan may not run long enough or too long.

[Bob Pietrangelo]

You have a heatpump. This the way it is supposed to operate, you probably have a problem with the heatpump or it is super cold outside. Check your filter to see how dirty it is. Then go outside and see if there is a little red buton in the front of the unit in the center about an inch up. If your outdoor unit is running do not worry about this button, if it is not operating. Make sure there is no snow and ice build-up on the coils or blades. If there is defrost it with buckets of hot water. Then push the red button. Another thing you can do is switch the stat to emergency heat. If you really do have a gas furnace, it might be multiple stage or could be your HP backup heat. Let us know what you found. No matter what call a lisenced and qualified Ruud dealer look at the equipment and check it out. Did they mention any discrepencies on the invoice when you got your preventive maintenance performed this season?

[TURTLE]

This is Turtle.

Until you tell use what type system you have and maybe a model number of both inside and out. Any answer given here would just be a little better than a guess as to the problem.

Tell use when this problem started and any details like you changed the thermostat last summer or 5 years ago. Tell use what you have and you might get a answer.

TURTLE

[HvacTech2]

Hi Burhans, hope you are having a nice day

On 09-Mar-05 At About 07:09:46, Burhans wrote to All Subject: Rudd Fan Thermostat

B> From: "Burhans"

B> All, I was having problems with my Furnace Fan staying on after the B> heat was finished blowing. I thought it was something with the B> furnace but after inspecting the Original Thermostat I noticed two B> mercury vials. The top one controls the fan and the bottom one B> controls the Heating/Cooling. When the Heat would kick off the B> mercury would move to the other side of the vial but the top mercury B> vial controlling the fan would not move to the other side for B> minutes to hours and sometimes all night long. Can I fix this or do B> I have to replace the 1988 Original RUDD thermostat.

B> Thanks, Everett

It sounds like you have a heat pump. if this is true it is normal for the heat pump to run constantly in very cold weather.

-=> HvacTech2