How do you adjust a gas valve on a furnace?

At this time, you can start the furnace and make your adjustments by turning the gas pressure adjustment screw clockwise to increase the pressure or counterclockwise to decrease the pressure. If you have a two-stage furnace, you will have to set gas pressure on both the low-fire and high-fire operation.

Can you test furnace gas valve?

Furnace gas valves are wired to an electronic component known as a solenoid, which receives signals from the thermostat control. Testing with a multimeter lets you know the valve works.

What happens if gas pressure is too high?

Improper gas pressure, on the side of the gas train can cause the unit to over heat if it is too high. Likewise, too much on the inlet side of the valve will cause gas valve failures or no heat because the valve cannot open against “high pressures”.

What should the pressure be on my furnace?

When the heating is turned on your boiler pressure should be between 1.5 and 2 bar. Most boilers will highlight this area on the pressure gauge in green to help you see if the needle is pointing to the correct amount of pressure.

How can you tell if the 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 much pressure should my furnace have?

In most cases, it should rise to about 20 psi while its heating element operates. That’s optimal at normal temperatures. Pressure changes of a few psi one way or the other can be brought about by atmospheric conditions. Most boilers are safe up to around 30 psi, at which point seals can begin to fail.

Do you need a manometer to check gas pressure in a furnace?

Before firing the furnace, you must connect a manometer to the gas valve, so that you have a reference point to check the pressure or change it if you need to. The manometer must be able to read in inches of WC (water column.)

What does the manifold pressure on a furnace mean?

Manifold pressure is the gas pressure that the gas valve delivers to the burners, to supply the BTU’s. How do you set the pressure? Before firing the furnace, you must connect a manometer to the gas valve, so that you have a reference point to check the pressure or change it if you need to.

Where do you put the gas pressure valve on a furnace?

The other type is a small tower connection (nipple) on the top of the valve. It usually has a hex type screw that is inserted in the tower. You backseat the hex screw one turn and install your hose directly over the tower and connect the other end to your manometer.

What should gas pressure be on two stage furnace?

If you have a two-stage furnace, you will have to set gas pressure on both the low-fire and high-fire operation. The valve settings are typically listed on the furnace’s rating plate, along with the desired temperature rise of the incoming air and outgoing air.