Gas Wall Heater Not Working: Pilot, Reset and Noises

By Ray Bennett · Updated 2 October 2026 · 6 min read · Checked against the maker’s manual

Gas Wall Heater Not Working: Pilot, Reset and Noises

Short answer

On a standing pilot wall furnace, the red reset button is the pilot button: hold it in while you light the pilot and for about a minute after. If the pilot will not stay lit, Williams points first at the pilot flame, which must touch the thermocouple, and at a pilot orifice blocked by spiders or webs. Its safety switches reset themselves once the heater cools.

A gas wall heater, or wall furnace, is a whole furnace in a cabinet on the wall: a burner, a pilot, a gas valve and usually a fan. Most stop working for a small number of reasons, and the owner’s manual covers nearly all of them.

This page uses the Williams owner’s manual for its Forsaire counterflow wall furnaces, which covers both a standing pilot and an electronic ignition. Other makers’ wall heaters work the same way, but always follow the lighting label on your own heater.

Before you start

What to carry: a torch, a long lighter if yours has a standing pilot, and a vacuum with a narrow nozzle. Fifteen minutes.

Gas or electric? Gas, on natural gas or propane. The fan and the controls also need electric power.

Which kind you have. A standing pilot model has a pilot you light by hand and a red reset button on the gas control. An electronic ignition model lights its own pilot when the thermostat calls.

Stop for these. If you smell gas. Williams says not to light any appliance, not to touch any electric switch or use a phone in the building, and to call the gas supplier from a neighbor’s phone. Smell near the floor too, because some gas is heavier than air.

A button that stays down. Williams says that if the red reset button does not pop up when you release it, stop and call a service technician or the gas supplier at once.

Never force the knob. Williams says to use only your hand on the gas control knob, never tools. If it will not turn by hand, call a technician.

Water damage. Williams says not to use the heater if any part of it has been under water.

The red reset button is the pilot button

Williams' lighting steps for its standing pilot models. The red button is held in while the pilot lights and for about a minute after.

Check 1Free, fifteen minutes

Light the pilot the way the label says

Shut down first. Williams says set the thermostat to its lowest setting, turn off the electric power, take off the control access panel, and turn the gas control knob to OFF.

Wait five minutes. Let any gas clear, then smell for gas, including near the floor. If you smell gas, stop.

Light it. Turn the knob to PILOT. Push the red reset button all the way in and hold it, and light the pilot straight away. Keep holding the button for about a minute after the pilot lights, then release it. The pilot should stay lit.

Then run it. Turn the knob to ON, which Williams says only works once the red button is back up. Refit the panel, switch the power on and set the thermostat.

If it goes out. Williams says to repeat the steps. If it will not stay lit after several tries, turn the knob to OFF and call a service technician or the gas supplier.

When the pilot will not stay lit

Check 2

Look at the pilot flame

The flame must touch the thermocouple. Williams’ first check is that the pilot flame reaches the thermocouple. A flame that is too low, or blowing too hard, lets the safety drop out.

A blocked pilot. Williams says the pilot orifice or its air hole may be plugged, and to check for spiders, webs or other organic material.

The thermocouple. It must be pushed fully into its bracket, and its fitting at the gas valve clean and tight. A worn one is a small, cheap part: why a pilot will not stay lit.

The vent safety switch. Williams lists its wiring, and a blocked or incorrect vent, as another reason the pilot drops out.

The safety switches that reset themselves

The automatic safety controls Williams lists. Three of them reset on their own once the heater cools.

Check 3

Let it cool, then find out why

The limit switch. Williams says it shuts the main burner down to stop the cabinet overheating, and resets when the furnace cools.

The vent safety shutoff. It shuts the burner down if the combustion products are not venting properly, and it also resets when the heater cools.

The fan motor’s overload. Williams says it protects the motor from current surges and from anything blocking the airflow through the heater. It resets itself when the motor cools.

Why it keeps happening. Williams says not to block the combustion and ventilation air or put anything in or on the cabinet. Keep furniture at least four feet from the front and two feet from either side.

It runs, but not right

Check 4

Check Williams' own list

Pilot lit, no main burner. Williams’ first causes: the gas knob not turned to ON after lighting, or the power to the heater switched off.

It shuts off before the room is warm. Williams says the thermostat should not be in the path of the heater’s warm air, near a lamp, or above a TV. Heated air hitting a large piece of furniture within four feet can also make it cycle.

It will not shut off. Williams says the thermostat wire may be shorted by a nail or staple, or cold air from an outside wall or a hole behind the thermostat may be reaching it. If the heater overheats or will not shut off, close its manual gas valve before you turn off the power.

The fan never comes on. Williams says the blower should start within three minutes of the burner lighting from a cold start.

Noises

Check 5Free, or a service call

Match the noise

Blower noise. Williams lists loose motor mounts, a blower wheel out of balance or loose on the shaft, a wheel rubbing its shroud, and a motor needing oil.

Ticking as it heats. Williams says the cabinet may be twisted or not level, making the combustion chamber bind as it expands.

A roar from the burner. Williams calls it burner resonance, usually on propane. A technician adjusts the burner’s air until the flame is soft and blue.

More noises. Clicks, clunks and blower noise on gas and electric wall heaters: a wall heater making noise.

Keeping it working

A check every season. Williams recommends a qualified technician check it at the start of each heating season.

Clean the burner area. With the power and gas off, vacuum the lint out of the burner compartment. Williams warns that lint in the burner’s air opening can cause a yellow flame, which makes carbon monoxide and soot. After about ten minutes of running, the flame should be soft and blue.

A Rinnai with a code. Rinnai’s direct vent wall furnaces show numbered codes: the Rinnai wall heater codes.

Questions people ask

Where is the reset button on a gas wall heater?

On a standing pilot model, it is the red button on the gas control, behind the control access panel. You hold it in while lighting the pilot and for about a minute after.

Why won’t my wall heater pilot stay lit?

Williams’ list: a pilot flame that does not touch the thermocouple, a pilot orifice blocked by spiders or webs, a loose or dirty thermocouple connection, a worn thermocouple, or the vent safety switch.

Why does my wall heater keep turning off?

Often a safety switch that resets when it cools, a thermostat in the heater’s own warm air, or furniture within four feet of the front sending the heat back at it.

Why won’t my wall heater turn off?

Williams points to a thermostat wire shorted by a nail or staple, or cold air reaching the thermostat. Close the heater’s gas valve first if it is overheating.

Why does my wall heater tick or make noise?

Ticking as it warms is usually the cabinet not level. Blower noise is loose mounts, an unbalanced wheel, rubbing, or a motor needing oil.

What should the flame look like?

Soft and blue, after about ten minutes of running. Williams says to call the gas company or a technician at once if it looks abnormal.

Sources: Williams Comfort Products owner's manual for the Forsaire counterflow top-vent gas wall furnace (standing pilot and electronic ignition models), including its troubleshooting chart