Suburban water heater back on-line

[KenB]

Last season our Suburban water heater didn't always light on the first try, or even second.  Once from inside I heard it light with a startlingly loud WOOF!  Not good.  On the second trip this season it quit working altogether.  This past week I started troubleshooting and found that they aren't that hard to work on.  This is what I found.

• I checked the gas supply by trying the stove and furnace.  Both worked, so it's not a gas supply issue.
• Watched and listened for the gas valve to open and the igniter to cycle.  I could hear at least one of the gas valves clunk open and could see the igniter try to spark.
• I pulled the orifice and orifice tube expecting to find a spider web or mud dauber nest like I did in a previous camper's refrigerator.  All clean, so not the issue.
• There is a high and low temp cut off switch.  Neither was tripped.  I don't believe the water heater will cycle the ignition circuit if either are faulty or tripped.  Mine was still trying to light, so I didn't think this was the issue.
• On-line reading said to suspect the coils on the gas valve.  There are two side-by-side.  Both need to open.  They are redundant for safety.  A local RV/Propane service shop gave me some used coils out of their junk box to try.  Swapped out the coils.  Still didn't work, coils were not the issue.
• Early on I should have tried lighting the gas coming out of the orifice tube with a camp butane lighter as the furnace went through its ignition cycle.  Finally did.  Lit just fine.  This would have eliminated any issues with the gas valve, coils, orifice, and orifice tube from my trouble shooting.  Learn from my mistake and don't jump ahead too fast.
• By now I notice a weak to non-existent spark.  Early on I thought it might be weak, but now it's not even present.  I now believe the spark got weaker as the ignition board warmed up during testing and cycling.
• All that was left in the ignition circuit to eliminate was the spark igniter and the igniter circuit board.  I ordered a both spark igniter and a Dinosaur Igniter board (Model # UIB S w/spade connector) off of Amazon.
• Since it was the least expensive and the easiest to get at, I Installed the new spark igniter first.  Still no love.
• Unplugged old board, plugged in the new Dinosaur board, turned on the heater switch, the water heater fired right up.  The igniter board was bad.  Old board wasn't hot, but was warmer than expected.

One of the traces on the old board looked a little warm around one of the transistors.  I'll have to look it over under a magnifying glass when I get a chance.  Might be good for a spare if I can fix it.

The existing cover won't fit over the new Dinosaur board.  Dinosaur sells their own cover to fit their own boards.  I'll put one on my shopping list for someday.

The old board was held in with double stick tape.  The new board is now in place with some VHB tape I had on hand.

That's it.  These aren't too complicated.  Though I wasn't interested in scheduling an appointment, the local RV service center was booked 6 weeks out.  Minnesota summers are short and I enjoy hot water in the camper.  Maybe this will help someone else troubleshoot and save a trip to the service center.

Ken

(Safety disclaimer - Follow at your own risk.  Beware of gas, high voltage from the igniter circuit, sharp edges on the water heater sheet metal, and the pointy end of the screwdriver.)

 

[John E Davies]

Cool I am glad you got it sorted. FYI, gas is dirty, even the natural gas coming into your house, and crud gradually builds up inside the tiny drilled hole in the jet. At some point it turns the flame to a weak yellow flickering one, not good.... Even if it looks clear, gently poke a dull object into it, and often you will feel the restriction go away. I have a set of old carburetor drill bits number 61 to 80, that I use just for this purpose. Push in the flat end gently by hand, not the pointed sharp end.

https://olivertraveltrailers.com/forums/topic/3243-how-to-service-and-inspect-your-suburban-hot-water-heater-gas-system/

I'm glad you did not scorch the hair off your arm, it is easy to get blasted if you are messing around trying to hot wire one of these..... Says somebody who got zapped....

John Davies

Spokane WA

[John E Davies]

Would you mind posting a link to the replacement board you used? 

Thanks,

John Davies

Spokane WA

[KenB]

On 6/1/2021 at 10:00 PM, John E Davies said:

Would you mind posting a link to the replacement board you used?

Here is the board I used.  There are two styles of this board; one with a blade connector for the igniter, and one with a stud connector for the igniter.  For my 2018 I got the one with the blade.  They are available from many suppliers, including Amazon.

HTH, Ken

(Out camping right now.  Enjoyed a warm shower just this morning.)