New article on spill switch inspection

Use this thread to discuss the entry New article on spill switch inspection at the InterNACHI Blog


It would have been more useful if the author included when (if any) year this device came into widespread use and if it is a building code requirement and where.

This is from the article:

Spill Switch Testing
Spill switches should be tested periodically. Remember to provide adequate ventilation while testing, or CO vapors might become overwhelming and cause personal injury. To do this, first turn off the appliance (we dont do this). Then, remove the vent from the flue and block the vent with sheet metal, plywood, rags or some other material (we dont do this). Turn the appliance on and wait; the switch should trip within 10 minutes, according to the American National Standards Institute, although many manufacturers have shorter time requirements. The switch should be replaced if it doesn’t open within the time specified by the manufacturer (where do we find this information??). To reset the switch, press the button between the switch’s wires.

Spill Switch Inspection
InterNACHI inspectors can test for the following spill switch defects:

  • The spill switch is missing. Spill switches are sometimes removed by homeowners or technicians who don’t understand the importance of these devices. If a gas-heating appliance isn’t equipped with a spill switch, look for it lying loose on or near the equipment. Also check for holes drilled at the edge of the draft hood, where the switch may have been originally installed. It would depend on whether the system was EVER equipped with this unit and whether the AHJ ever required it!)
  • The spill switch was never installed. **Spill switches should be installed on older systems that were never equipped with the device. The gas control valve will need to be replaced if it is not compatible with the new spill switch. *(Sorry. This may not qualify as a material defect, and the cost of an installed gas valve is often close to the value of the system. Further, the Seller will argue that the system functions fine, and is in the same condition as the day it was installed.)