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The furnace gas valve operates by electromagnets. The primary valve — also known as the safety valve — supplies gas to the pilot light. Without adequate heating of the thermocouple or thermopile, the furnace gas valve closes. As a result, this cuts off the supply of gas to the pilot light.
What causes gas valve failure?
The valve itself may have simply worn out or may be damaged due to basement seepage or submersion. Alternately, one of the electronic gas ignition components or a glitch in the safety circuit may be to blame. If your furnace has a standing pilot light, the thermocouple could be worn out.
How does a gas boiler gas valve work?
A boiler gas valve controls the flow of gas to the pilot light and burner. It’s controlled by an electrical signal coming from the printed circuit board (PCB). The PCB detects that the fan is operational, ready to expel dangerous flue gases via the flue. The gas valve opens to allow fuel into the burner and pilot light.
How does a gas valve open?
Gas shutoff valves When the long side of the nub or handle is parallel to the incoming gas line, it’s open and the gas is flowing. When it’s turned a quarter turn, perpendicular to the incoming pipe, it’s closed.
How do you know if a gas valve is bad?
If 24 volts is coming from the board to the gas valve terminals and you don’t hear that little clicking noise the internal valve makes, you could have a bad gas valve. To double-check, take the leads off to the gas valve and check there. Got 24 volts? Then something downstream of that 24 volts is not working.
How do you test a gas solenoid valve?
How to Test a Gas Valve Solenoid Coil Unplug the appliance from the wall outlet. Use a flashlight to inspect the interior of the burner assembly. Watch the igniter tip and count the seconds while it remains on. Unplug the appliance from the wall outlet. Set the multimeter to the ohms-times-10 setting.
Can a gas valve be repaired?
The gas valve cannot be repaired in the field. Only the gas valve manufacturer or someone certified by the manufacturer of the gas valve can make repairs. Then re-certifying the safety of the gas valve. This also applies to gas valves that have been submerged underwater due to flooding.
How long should a gas valve last?
Gas Valves are routinely checked for 100,000 cycles and are used in equipment that have approximately 15 years life expectancy.
Can a gas valve break?
Although relatively rare, gas valves can fail causing a fire or explosion. Gas valves can fail from a variety of causes including contamina- tion, product deficiency, and misuse.
How do you test a gas control valve?
How to Check the Furnace Gas Valve With a Multimeter Turn off the furnace at the wall control. Take out the bolts in the service panel on the side of the furnace using a nut driver. Pull the wires off the gas valve terminals. Turn the test control on the multimeter to “mV,” which stands for millivolt.
How many valves are in a gas valve?
How A Furnace Gas Valve Works. There are essentially two valves that make up your furnace’s gas valve, and they are positioned in series, or one after the other. The furnace gas valve operates by electromagnets. The primary valve — also known as the safety valve — supplies gas to the pilot light.
How do you know if a valve is open or closed?
Ball valves are perhaps the easiest valve to see if they are open or closed. If the handle on top is parallel to the valve, it’s open. Likewise, if the handle is perpendicular to the top, the valve is closed.
What happens if gas valve goes bad?
If the gas valve is stuck or otherwise malfunctioning, your furnace may shut down completely or just stop delivering warm air. There are other issues that may cause the same symptom, so you need an experienced technician to diagnose the problem and apply the proper repair.
What happens if gas pressure is too low?
If the gas pressure is too low, your furnace’s efficiency will go down. Not only that, but it will lead to a greater amount of condensation of burned gases. That’s because it greatly increases the risk of furnace overheating. When this happens, all manner of internal components may become damaged by the excessive heat.
What does gas control valve failure mean?
On a gas water heater, the gas control valve contains the thermostat and pilot light controls. Water heater problems that may be caused by the gas control valve include a faulty hot water heater thermostat, faulty gas valve, pilot light that won’t light, and tripped heat limiter.
What does MV and PV stand for on gas valve?
Some valves have more than two wires controlling the valve. These are usually a PV (pilot valve), an MV (main valve), and a COMMON wire.
How many ohms should a gas valve read?
Test the coils with an ohmmeter with the wires disconnected (you only need to disconnect one wire on each coil) and you should get around 40-60 Ohms resistance at the two leads of each coil. If the meter reads much lower or much higher then the coil is bad and needs to be replaced.
