hi-am wondering if any out there know about the summer switches on furnaces.i believe they are supposed to allow the blower portion of the furnace to run in order to help in circulating air in the home in the summer months.i have a neighbor whose furnace blower is running constantly.is it supposed to or should it be thermostatically controlled?i am concerned that if it continues it will ruin the blower motor when it is needed most[winter].this neighbor has never touched the furnace-it just runs by itself[?]......thanks-devon

Your regular thermostat contains two fan operations:

1. Auto - The fan comes on only when the temperature setting calls for heat or A/C. Once the room reaches the desired temperature, the fan turns off.
2. On - The fan will run all the time, no matter if the heat or A/C kicks in.

If you want to circulate air, the the 'ON' setting will do it. I guess in theory doing this will reduce the life of your fan motor but not sure you'll even get there. While most of the time we keep our fans in the 'auto' position every spring we run the fans in the 'on' position for 6 to 8 weeks. We do this during allergy season to use our allergy filters.

Most motors tend to wear out a bit faster from switching on and off constantly, running them on does not seem to affect them, at least in our experience.
In the air conditioning season (se NEbraska) we actually leave our fan running 24/7. Ours does cycle to a higher speed when the compressor is running and the lower when not to save energy. It helps to circulate the cool air throughout the house. In winter we leave it on auto.