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I have a ceiling hung gas reznor heater-about 60k btu, in my warehouse.
Today, this heater wasn’t getting up to temp as quickly as usual.
I investigated and noted that the flame seemed to be very low-like not enough gas pressure.
I thumped the gas valve and it fired up high, like normal. Then soon went back down. The fan seemed to be cycling off as well-like it’s sensing low heat.
Needs a new gas valve, right? The heater is probably at least 20 years old. No other controls other than the gas valve and the thermostat. Very basic.