water heater won't stay lit

[Roop-Dogg]

my gas water heater will switch on, the fan will start and the burner will lite and burn for 2 or 3 seconds and then go out. after about 20-25 seconds, the igniter will glow, the gas will lite again, burn 2-3 seconds and go out again. this will happen 4 or 5 cycles and then the fan and water heater will shut off with out heating the water. after about an hour or so the whole cycle will start and repeat without the burner staying lit.

i have found thru trial and error that if i hear the fan kick in on the water heater, i can go down and take the cover (approx 4 x 6") off the bottom and hold a towel or something over the opening and most time the burner will stay lit....kinda like i'm choking it.

anybody have any idea whats happening or what i need to do to correct this problem. its been doing this for a couple of months. i have checked the exhaust pipe for obstructions and didn't see any.

[CAMAN]

More than likely the thermocouple. Taking some steel wool to it then cleaning it with some rubbing alcohol may fix it. If not replace it.

[Surface Tension]

Could be that or your increasing the vacuum on a pressure switch or increasing air flow.

Take the model number down off the heater and download the manual.

Go through the maintenance and cleaning part and then the trouble shooting.

[nobody05]

on some power vent heaters on the way way bottom of the heater you have to stand on your head to see it. There is a screen somewhere, sometimes all the way around the heater sometimes just a little area with a screen/filter over it that can become clogged therefore not getting the correct amount of air to burn properly. Check it out. Otherwise take the entire burner out and vacuum out the entire burner area of the water heater. Rust can flake off the heater and fall on the bottom air inlet also. Some things for you to look into

[echotrail]

I agree, it's likely the thermocouple has gone bad. It's a cheap and easy fix to do yourself. however, if your water heater has reached it's life expectancy plus a few years you may want replace it.

[Tom7227]

I have a Rheem unit and was having trouble with it. I called their customer service and they helped me fix it in about 5 minutes. Might be worth seeing if you can get some advice from the folks with the company that made it.

[corncob]

I would start with the thermocouple first as it is likely the problem and cheap.

[mnguy152]

I had same problem I shut off the gas remove the burner and cleaned up the pan put it back togather and turned gas back on and everything was good to go.

[Jigging Joe]

Mine did the same thing, I took sand paper and lightly sanded the thermocouple (maybe the glow rod too??) and its worked good for 2 years now.

[Roop-Dogg]

pretty much what i ended up doing. took it apart and cleaned it up the best i could and put it back together. i also took a pliers and just very slightly ra-aligned the bracket that holds the thermocouple so that it points more directly toward the flame. its been working now since sunday morning. thanks for all of your help!!

[CAMAN]

Without seeing it in person I'm guessing covering the opening changed the airflow inside and moved the flame to hit the thermocouple better. Glad it all worked for you.