Bad gas valve?

Dsisson

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.

JUGHNE

Would there be an in line gas regulator ahead of the gas valve that your "thumping" could have affected?
I would still check the incoming pressure before changing the valve.

EBEBRATT-Ed

What @jughne said. Also look at the gas valve and wiring to determine if it is 2 stage (not likely)

Check the regulator vent opening/vent pipe.
dirt, dust, wasps, bees have been known to plug the vent pipe especially if it extends outdoors. If the regulator can't (breathe) it won't work right

Dsisson

From the gas valve-downstream the only thing is the gas meter. 1 other similar heater in the gas line has excellent pressure.

Upstream is the heater itself. It’s single stage. Really simple reznor ceiling hung heater.

Probably is the gas valve. I’ll see if I can determine model numbers tomorrow.

HVACNUT

Lotta dust around settling up high in the warehouse? Check/clean the burners if needed.
Steady low flame or erratic?
Possible bad wiring connection? All is tight?
Someone bang into the thermostat with the Hilo?

DZoro

Is there a pressure switch on that unit? If so confirm chimney and port are clear of debris. Make sure no condensate is in the pressure tube or switch.
Constant 24 v to valve, especially when it is acting up.
And all the other suggestions!
D

Dsisson

I think I better call a professional. I'm just a building owner, and a bunch of those things are above my pay grade.

The flame is steady low, until I bump the gas valve, then it goes high like it's supposed to. All wiring is tight. Unknown if it's getting a good 24 v or not. The unit is located in the lobby, so no physical damage.