A.O. Smith NG water heater won't light

[aesterling]

I’m having an issue with my A.O. Smith direct power vent natural gas 50-gallon water heater (Model #: FPD-50-J00N010543). The unit isn’t igniting. When I plug it in, the inducer/blower motor starts, and I hear a click from the gas valve, but the hot surface igniter doesn’t glow. It attempts the start-up cycle several times before going into lockout. It's very old and will be replaced soon, but I'd like to get it working until then.

The status light flashes 6 times after a failed start-up attempt, indicating a system lockout. The water heater worked fine yesterday, but the circuit breaker it’s connected to tripped last night. It may have been tripped by other devices on the circuit (outdoor Christmas lights) but may have happened during the water heater’s start-up sequence.

The intake and exhaust PVC lines look clear. I have a new/spare replacement blower assembly in a box that has never been installed.

I've cleaned the flame sensor in the past when the unit wouldn't stay lit, but the hot surface igniter doesn't even appear to be starting now, so I don't think that's the cause.

Please let me know if you have any suggestions. Thanks for any advice!

 

[Sylvan]

Whomever installed the gas piping needs to have their license revoked.

I wonder if anyone bothered to read the directions about soldering a joint within 6" of the tank?

Also, there is something called "electrolytic action" when ferrous and nonferrous metals come into contact with each other which in civilized societies are against plumbing codes.

I don't understand why the installer did not use a dielectric union to prevent the different metals touching and a union makes it a lot easier to replace the tank when needed.

For an extra $20 the installer should have had the decency to also install an isolation valve on the HW line so there would be no need to drain the system when replacement is needed.

How old is this heater?

 

[Sponsor]

 

[Master Plumber Mark]

Son, you are totally out of luck with that Smith water heater... I can see on the rating tag that it is a 1999 heater so
that makes it 25 years old..... That blower motor that you have in a box is rare indeed if it actually is a 1999 replacement unit

Put that new motor on E-bay and try to sell it to some sucker trying to resurrect their unit...

Seriously , you are not going to find parts or anyone willing diagnose what is going on with that old clunker.
Also the gas control is too outdated..... we used to have troubles with them along time ago
and it normally had to do with a bad pressure switch.. but that was back in around 1995...


They have streamlined these power vents a whole bunch since those days

You are going to have to put that old dog down and if you know what you are doing I suggest going to
home depot and getting a 50 gallon Rheem power vent unit and install it yourself

Or you can call a plumber and have them tear out that antique and install a new rheem 50 gallon power vent unit
with an 8 year tank warranty....probably going to cost you about $2900...more or less depending on where you are
in the USA

 

[Fitter30]

Hot surface igniters don't last for ever trace the wires back see if there's voltage 120vac. Appliance parts house might have one take it to them. Might not be able to find one. Heater looks 15-20 years old?

 

[aesterling]

Thanks for your help, @Sylvan, @Master Plumber Mark, and @Fitter30. Much appreciated!

I'm going to replace it with a new unit rather than spend time and money on the 24-year-old heater.

Do you recommend I replace it with a matching direct power vent unit like this (in stock at Lowes) that uses the two existing PVC pipes for combustion air and exhaust?

Or do you recommend a power vent unit like this (in stock at Home Depot) that only uses one PVC for exhaust and room air for combustion?

 

[Reach4]

In general, using outside air for combustion prevents the WH from generating a vacuum indoors. A vacuum sucks in outside air.

I am just commenting on the general concept, and not the particular units.

 

[Fitter30]

Use the one from lowes. It will be more energy efficient. If you want to see how tight your house is there is a blower door test. A lot of electric companies offer a blower door test that is included in a energy audit usually at reasonable cost.

 

[aesterling]

Thanks, @Reach4 and @Fritter30

I picked up the one from Lowe's and will install it this evening. The blower inlet/outlet are in different locations, so that will take some reconfiguring, but the rest should go quickly.

It's surprising how much lighter the new unit is compared to the old one from 1999, despite the same brand and style.

 

[Master Plumber Mark]

Use the one from lowes. It will be more energy efficient. If you want to see how tight your house is there is a blower door test. A lot of electric companies offer a blower door test that is included in a energy audit usually at reasonable cost.

I disagree with you about this... I would rather go with a Rheem Power Vent heater from Home Depot ....
Just cut off the intake line at the floor and leave it for air combustion for the new power vented
heater you are gonna buy

Actually you are 100% better off to go to a real legit plumbing supply house that sells Rheem or Smith and get one
from them ...... Real plumbing supply houses carry replacement parts for the product you buy....
Lowes and Home Depot do not have repair parts in stock for power vented heaters
so they would have to order you the parts and it could take a week or more before they finally show up

good luck

 

[aesterling]

@Master Plumber Mark I appreciate your help! I'm sure you're correct that the commercial/pro product lines are a better choice and have replacement parts available, but I needed to install a replacement as quickly as possible so the family would have hot water.

The replacement A.O. Smith power direct vent that I installed is working great so far and I used all the same connections from the old water heater. We'll see how long it lasts. If it gives me a lot of trouble, I'll be sure to take your advice for next time and get one from a plumbing supply house instead.

 

[Master Plumber Mark]

@Master Plumber Mark I appreciate your help! I'm sure you're correct that the commercial/pro product lines are a better choice and have replacement parts available, but I needed to install a replacement as quickly as possible so the family would have hot water.

The replacement A.O. Smith power direct vent that I installed is working great so far and I used all the same connections from the old water heater. We'll see how long it lasts. If it gives me a lot of trouble, I'll be sure to take your advice for next time and get one from a plumbing supply house instead.

Its not going to give you any trouble.... you are good for 10 to 15 years...
I doubt you will get 24 years out of this one