Friartuck
Well-known member
Unit is a Trane ceiling suspended forced hot air unit (approx 30K BTU) with Johnson electronic ignition and direct vent (no blower), GAND series if I remember right. This is a used unit that has not been in service for over a year. The gas valve and ignition works by jumping with the transformer, and blower fan operates when connected to 110V so that is a good sign that individually the main components work. Unit has a three lead switch in the burner area and a time delay switch in the electric box.
1. What is the purpose of the three lead switch in the burner? Is this also called a hi-lo switch? Appears to be in series with thermostat leads. Is it a Normally Closed (NC) and Normally Open (NO) switching arrangement?
2. The time delay switch appears to have switch leads controlling the blower fan. Why is it necessary to delay the blower fan? Is it trying to anticipate when the burner is up to temp? The 24V transformer appears to have one leg of the low side run through the delay switch. Running it through the thermostat so that when the stat calls for heat, the time switch begins? Is that correct?
1. What is the purpose of the three lead switch in the burner? Is this also called a hi-lo switch? Appears to be in series with thermostat leads. Is it a Normally Closed (NC) and Normally Open (NO) switching arrangement?
2. The time delay switch appears to have switch leads controlling the blower fan. Why is it necessary to delay the blower fan? Is it trying to anticipate when the burner is up to temp? The 24V transformer appears to have one leg of the low side run through the delay switch. Running it through the thermostat so that when the stat calls for heat, the time switch begins? Is that correct?
Last edited: