Posting 2nd message. Found problem of low flame on one burner. Piece of teflon tape caught in orifice of burner log. Main question: Furnace burners run for about 15 minutes and then shut off. Rest for about 5 minutes and then furnace is back on for 15 minutes. This cycle continues all day. Result is low how water temp in baseboard heating units in house. Perhaps has something to do with an overtemp switch? Is this shutting down furnace. Thermostat is still calling for heat but house only get to 62 F. Question: Why is it sutting down?