Testing Furnace Gas Control Valve

I will be checking various gas valves to see if you can check the continuity of the solenoid with an ohmmeter.

Testing furnace gas control valve.

Some gas valves cannot be checked with an ohmm. If so and the boiler or furnace isn t firing up then you need a new gas valve. Step 1 check for coil burnout. The ignitor will be 120 volts the gas valve is most likely 24 see if your transformer shows voltage on the secondary terminals.

If replacing the thermopile doesn t work then you need a new gas valve. Everything that applies to the electronic ignition sequence of operation by the way of the safety circuit must be proven before the gas furnace will allow the gas valve to fire the main burners to provide heat. Pull the wires off. If you do get voltage then i would be testing for gas pressure before the gas valve and the manifold pressure when the gas valve has voltage.

Locate the hot surface igniter and look for a spark or glow there. Coil burnout failure to open failure to close or solenoid valve noise. If solenoid valves are malfunctioning dangerous pressure might build up and cause damage. Locate the front lower access panel to the appliance.

There are four possible reasons for solenoid valves malfunction. How to check the furnace gas valve with a multimeter step 1. The following steps will show you how to troubleshoot gas control valve solenoids. Take out the bolts in the service panel on the side of the furnace using a nut driver.

Standing pilot gas valves. There should not be a flame up there if the valve is working correctly. Standard solenoid valves are used for pneumatic gases. Testing gas pressure at the valves is often the first thing hvac technicians do when they are called in to check on faulty furnaces.

Turn off the furnace at the wall control. Check to see if you re getting 24 vac at the terminals on the gas valve. The difference is the standing pilot gas furnace always has a pilot light on. Turn off the gas supply valve to your appliance to test whether your valve is capable of shutting down properly.

Set the thermostat or the device s controller slightly above the current room temperature. Locate the gas valve. Wait for the unit to cool if it has been in use. If the appliance is a boiler or furnace it ll use 24 vac to operate the main valve.

This valve is usually found in the wall line leading to the dryer and is shut off by turning the handle perpendicular to the gas line. Turn off the gas feed line valve to the dryer.