power vent hot water heater

[artieb]

Hi, I have a LP, power vent hot water heater that is cycling. Vent fan runs, switch closes, ignition begins. Runs for 10 seconds. Repeats, the vent exhaust screen is clean. I'm wondering if a thermocouple would do this?
Any trouble shooting tips?
If i unplug it, works for a while then, issue returned. Thanks Artie
EDIT AFTER SEARCH I'll clean my flame sensor and go from there

 

[plott hound]

yup,flame sensor

 

[buddyboy]

it could be the air pressure switch on the vent, mine was doing the same thing.

my switch was bad, making the water heater think that the vent was blocked, we tested by shorting the switch wires with a jumper.

it was a 30 or 40 dollar part.

 

[wnstwolf]

Would also look to sensors on exhaust. Last Winter I was realizing similar symptons you are seeing I went out to LP tank and it was almost empty so thought it was that. After tank filled still an issue and cleaned senors and ran through all sorts of diagnostics with Rinali techs over phone. After that went upstairs to chill out and looked outside as the fourth heavy snow storm of the winter was coming down hard...

Looked out back and the lightbulb clicked. Snow had slid off roof and piled at back of the house almost 3' high. totally blocked the vent!!!! Doh! a quick shovel and hot water was flowing once again..

I sure hope you dont have snow yet but maybe a bees nest or something in the pipe after the screen?

 

[artieb]

I wasn't sure if I had a flame sensor. My heater is older and has a spark ignition and a thermocouple. I cleaned up the burner assembly and it up and heating.
I have had no heat and was very small amount of blockage in the exit screen in the past.

 

[kbs2244]

It may be all the safty things are working correctly.
I would check for a clogged vent.

 

[jhelrey]

Is it flashing a code?

 

[Tinman7783]

If the vent was plugged the water heater would not try to lite at all and the vent motor would just keep running until the air proving switch was made. My bet is the flame rod or a combo of the flame igniter/sensor needs cleaning. Good luck.