Eleven Tips for Adjusting a Furnace Gas Valve

An inside look at the back of a gas furnace.
  • 1 hours
  • Intermediate
  • 0-100

A furnace gas valve supplies the burners of the furnace with gas. This flammable substance is supplied once the burners heat up enough so as to allow combustion.

As such, it is obviously an important part of your furnace that should be set correctly. Here are eleven tips to help you adjust this valve.

1. Check the Pressure

Do not adjust your furnace to a pressure other than recommended by your manufacturer.

2. Follow the Right Procedure

The knob that controls the valve should be turned “on.” Turn up the necessary thermostats so the furnace fires, and check the pressure on the manometer.

To make adjustments, locate and remove the cap that covers the pressure regulator screw. You can then make adjustments to the pressure in the upward or downward position.

3. Check the Pilot


If your furnace does not produce any heat at all it could be because your pilot needs to be relit and the gas valve is not open.

In some cases the thermostat could not be functioning properly, so you should check the pilot and valve.

4. Call for Help

If your gas furnace is not working, instead of trying to adjust the gas valve of a furnace, call in a service technician to find out what the problem is.

5. Clean the Crosslighter

If there are multiple burner tubes, before adjusting them, pull the burners and ensure you clean the cross lighter.

6. Adjust the Regulator

Very often the gas pressure is too low. This could be because the gas valve or regulator may not be adjusted properly. As a result, the flame provided is unsafe and inadequate.

This problem can be rectified by adjusting the regulator. You would, however, have to know what is causing the problem. Boosting the pressure at the valve level is not advisable as it might be unsafe.

7. Ensure Optimum Settings

For your system to heat effectively, you have to ensure it can be adjusted so it can run continuously even in the coldest weather.

8. Adjust the Flow of Gas

repairing a gas furnace

The flow of the gas can be altered with the help of a screw that is beneath the big screw or the cap screw. By turning this smaller screw counterclockwise, the flame can be increased.

9. Adjust the Pressure

If you turn the adjustment screw for pressure in a clockwise direction, it will give more pressure. Similarly, turning it in the counterclockwise direction will give less pressure.

When you are trying to make these adjustments on your own, make sure you do not turn the screw more than a quarter turn either way.

10. Check the Sequence

Check the sequence followed by the furnace right from the time it starts up to figure out if you have a faulty gas valve. Do not try to adjust the valve if you hear a “hissing” sound while trying to ignite the gas.

11. Keep the Right Range

The amount of gas that goes to your furnace should be allowed to vary from anything between 40 and 100 percent. This will help you save energy.