hot water heater trouble

[Cal_stir]

if it is a power vented unit then there will be 1 or 2 pressure switches that determine if the vent is venting properly, one of the most common problems is a blocked condensate drain that allows water to backup in the pipe causing a blockage in the vent which causes the unit to shut down, in this case, the unit ussually starts briefly and then shuts down

[The Codfather]

Jason,
Give me a call, I'm at home right now with a sick kid but can probably walk you through it.

[bignose]

I found the parts list and I need some help identifying the flame sensor.
I believe it is part# 25 called fv sensor.

[Cal_stir]

does the hot surface igniter glow red hot while the unit is trying to ignite?
the FV sensor is a Flamable Vapour sensor, it will lockout the unit if vapours are present, gas vapours, paint vapours, etc.

[bignose]

When I turn on the tank the fan turns on, glow plug heats up, burner ignites for 5-10 min. and then it shuts off. It cycles twice then turns off and goes into vacation mode.

is the fv sensor the metal rod that has to be cleaned?

[bignose]

Now I'm confused, my hot water heater is working again.
Seems to be related to cold weather because it was -30 when it stopped and today it's -18 and its working .

[Cal_stir]

Originally Posted by bignose

Now I'm confused, my hot water heater is working again.
Seems to be related to cold weather because it was -30 when it stopped and today it's -18 and its working .

I would suspect a problem with the vent or the pessure switch for the vent, extreme cold and or high winds could cause an abnormal pressure.
The pressure switch is # 27

[Cal_stir]

Originally Posted by bignose

Now I'm confused, my hot water heater is working again.
Seems to be related to cold weather because it was -30 when it stopped and today it's -18 and its working .

Is the water heater running on natural gas or propane?
propane pressure is affected by the cold.

[Cal_stir]

no, the FV sensor senses the pressence of flammable vapours, a flame sensor is a metal rod that will produce a voltage when heated, detecting a flame