Gas wall heater shuts off @ 70*

Are you holding down the pilot light button long enough for the heat sensor probe to get hot and turn on the gas valve? It takes up to 3 minutes

Does the pilot light stay lit if you continually depress the control valve?
If the pilot light stays lit as long as you keep the valve depressed, then the problem is the thermocouple is bad. The pilot light makes enough electricity via the thermocouple to hold open the gas valve that feeds the burners. If the thermocouple fails to produce that electricity, the gas valve will shut down and switch off the gas flow to the whole unit.

yes look at gas valve turn to pilot hold down for about a minute then light pilot generator keep holding button down for about 2 minutes then turn to on should stay lit if not need new pilot generator

Under the gas valve is a removable panel. On models of that era there should also be a second panel behind the first. remove both.

the pilot light should be clearly visible.

If no pilot, turn the gas valve to OFF. wait 60 seconds. locate the tubes from the gas valve to the pilot location. turn the valve to pilot, and with a long match or grill lighter lit, place flame at the pilot location and press down on the pilot button beside the main valve.

pilot should light. If not shut off the gas and call a technician. If yes, hold the pilot button for 60 seconds, then slowly release. Pilot should stay lit. If not, shut off gas and replace thermocouple, start relight sequence over. If pilot stays lit, replace inner cover and adjust temp to 120 deg. If heater fires up, replace outer cover. Done.

If heater does not light, replace gas valve or entire unit. Water heaters have a limited life expectancy, and if my recollection is correct your unit is 10yrs past warranty.

When it is running check the flame. It's triggering a rollout switch.

Turn the Gas Control Knob inside the heater compartment from OFF to PILOT. Push in the knob and hold it, at the sametime push the ignitor button (will probably be a Red button). Once the pilot lights, continue to hold the Control Knob down for one minute. Then ease off of it. If the pilot stays lit, turn the Control Knob to the ON position. The burner should light, if the Thermostat is set higher than the ambient temperature in the house. If the Ignitor button doesn't work, you can match light the pilot. Just be careful and follow the instructions above, once it's lit.

Hope this helps solve your problem.

Move the gas valve knob to the PILOT position and press down on the knob. You will be pressing down on a spring loaded safety magnet. Now light the pilot and keep holding down the knob till the thermocouple gets hot enough to produce electrical current and hold that spring loaded magnet in. This is your safety device. If the heat gets too hot the furnace has a fuse in line with that magnet.
When the pilot stays lit by itself without you having to hold down the button then advance the knob to the ON position. Then go to the wall thermostat and turn on the heater.

HOW IT WORKS: WILLIAMS WALL HEATER

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look at gas valve, there should be a knob on valve, turn knob to pilot and push button in and hold, the silver tubing coming off valve follow it under the burner, as your holding pilot button down light the endunder burner, if flame appears hold pilpt button down for about a minute then change valve to on and pilot should stay lit, if pilot goes out redo and hold longer, the thermocouple may need to be cleaned.

The power pile (pilot generator) is defective. It produces a milivolt signal to ensure to keep the gas valve open. If it goes bad, the valve thinks the pilot is out, even when you are holding the button down, so when you release the button, it shuts the gas off to prevent excess gas buildup and a possible explosion.