Water heater won’t start

[Rhilyar]

I have a 2000 WB C CLASS 32 ft. When I turn on the switch I hear it click on and shortly after the light comes on, there is a brief odor of propane and then nothing. After a few tries it still won’t work. I have replaced the ignition board, the thermostat assembly and the spark and sensor electrode. I tried calling the Atwood company but bo help there. Has anyone had this problem?

[creativepart]

What about the orifice where the propane exits the gas valve? Those can get clogged. Be careful not to try to clear it with anything too large because if you make the hole even slightly larger it can ruin it. Of course, it's fairly easy to replace the orifice entirely.

Also, is the gas tube between the orifice and the combustion chamber lined up straight. If they are way out of alignment it can effect this function.

Also, have you opened the WH door and watched what is happening when it tries to light?

You've already replaced 1/2 of the WH's internals.There is not much left.

[Rhilyar]

Thanks for the quick response, the weather here is freezing so it will be a while before I can try your advice, those are a few things that I did not think of, I will repost when I do. The only other thing that I tried, and yes it was unsafe, I held a long bladed lighter inside the burn tube while someone else inside tried to start it, it ignited only for a second or two and then shut off.

[AZAspect]

Creativepart has listed just about everything left that you can check. I echo to have someone operate the switch and you be where the unit is and witness what is going on. If you have spark and you are still smelling propane my money says it is either the orifice or the alignment of the combustion chamber. Let us know what you find out...always interested in the final outcome so when it happens to me, I know where to look! Good luck!

Al

[creativepart]

You did say you replaced the circuit board - correct?

Also, the flame sensor?? I think it's a thermistor, not positive.

One thing you can get from Atwood is a list of specialized servicing dealers. They list different service centers for different products. Just look for the ones for WH near you.

[Rhilyar]

Thanks again, this gives me something to check, I’ll make sure to post when I figure this out.

[WoodBoss]

make sure you can see the spark when it goes to light. Bugs and spiderwebs can keep it from lighting, I had to clean and vacuum the area to get it to light reliably.

[jerrybb]

One more thing, your air/gas mixture could be too lean and not lighting properly. Try closing down the air damper so you get a more yellow flame, then gradually adjust for a better mixture. I like mine a bit on the rich side, blue with some yellow flame but not too yellow. It lights better and is quieter.

[Rhilyar]

Thanks for the information, another thing I need to check.

[TTFoley]

Here's my two cents worth. This can apply to any of the gas burning appliances in the RV.

Propane gas as it's produced in the refinery is odorless. The refinery adds a compound called mercaptan to the propane for safety, as its the mercaptan that gives propane, butane, natural gas, etc. its putrid smell. Mercaptan is a slightly oily substance. Only a very small amount is added to liquified gases. (I believe it's something like 30 oz added to 30,000 gallons of LPG). If, during colder temps, we travel with one of the propane appliances lit, let's say the refrigerator, the mercaptan can rise to the top of the propane tank or bottle. As the gas is removed from the tank, an out of normal proportional amount of mercaptan is withdrawn also. Because of the colder temps and its oily, sticky nature, it tends to stick to parts in the regulator, gumming it up causing it to malfunction.

The only fix is a new regulator. Newer regulators are 'supposed' to not be as prone to the gumming nature of mercaptan. Most LPG tanks on RV's are plumbed with a pretty large loop of hose right after the tank regulator and before it enters the hard plumbed RV gas system. If your regulator is gummed up, there is a really good chance that some mercaptan has pooled at the bottom of this loop of tubing. If so, it needs to be removed, because if it (mercaptan) were to get in the valves of our appliances, we are talking big $$$$.

If you are replacing the tank regulator, also remove the loop of tubing between it and the RV gas piping. Mercaptan is not water soluble. To remove it from the flexible hose, spray carburetor cleaner or ether (be EXTREMELY CAREFUL if you use ether, it is extremely flammable, but also an extremely good solvent). I would stick with carburetor cleaner. Spray it in the hose, plug both ends and slosh it back and forth for a while. Drain the solvent into a safe container and use an air hose to thoroughly remove the liquid and dry the the interior of the hose. Reattach the hose to the RV gas pipe and your new regulator.


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