Hello,

I have a Rheem combination heating and cooling rooftop unit equipped with intermittent ignition and it's probably 10+ years old. The problem is that it won't light. I turn on the thermostat to call for heat. The vent motor turns on and then the ignition spark is energized, (I can see the sparks coming from the ignition switch, through the little window on the unit). At this point the pilot valve is supposed to open and the pilot burner should light, but it does not light.
A day prior to having this problem, I had to turn off my gas main to replace my water heater. The gas main is back on (PG&E verified this) and the water heater works fine, but the roof top Rheem heater won't kick in.
Does anyone have advise on how to get this pilot burner lit? Or what part I should check or replace?

Thanks for your reply'
-Brandon

You Might Keep Trying, Most Of The Time You Need To Get All Of Thair Out Of The System Before The Gas Will Operate Properlyit's What You Call Bleeding The System. If There Is A Union Near The
Unit You Can Crack It A Little Until You Smell Gas, Then Quickly
Tighten It Back Up. Do Not Have Any Open Flames When Doing This.
Some Units Will Try To Start Everal Times And Go Into Lockout Mode. If This Happens Just Turn Off Your Power And Turn It Back On. If That Doesn't Work You Probable Have A Bad Gas Valve.

Make sure there isn't a valve on the line to the furnace that was shut off. Shouldn't have needed to have been, but could have. Check and see if you have 24 volts on the terminals to the gas valve. If you have power, but no gas, the valve is bad. I have never changed a gas valve, and am afraid they may need professional adjustment when changed.

I want to say thank you to those who responded to my January 30th post titled "Rheem roof top heater". I ended up calling a professional company out to fix the problem. It was a bad gas valve (made by Honeywell) that was clogged or worn out. It was not allowing gas to the igniter. The technician spent about 30 minutes replacing it. The total cost of the service was $595.00. He waived the $85.00 It cost just to get him over to my house to diagnose the problem, which the company promises to do if I hire them to do the work. I also negotiated $50.00 off the technician's original quote to replace the valve.
This was the first time I've dealt with a heat/AC problem and was a little shocked at the expense to fix the problem, but I doubt if I would have figured it out myself. Now that I've seen how it's done, though, I think I would attempt to replace the valve myself next time.

Thanks for the report. There are many simple repairs the average home owner can make, saving a bundle. Not sure this would have been one. As I said in January, a new gas valve may need professional adjustment. Your next problem may in an area I am more confident of.