HOW TO: service and inspect your Suburban Hot Water Heater gas system

[John E Davies]

This is a super easy appliance to work on. One reason I did not buy the Truma heater is that it can't be worked on by the owner. The only thing you can't easily do with the Suburban as an owner is check and adjust the gas pressure. This thread won't cover anode replacement and other "wet" stuff like flushing the water tank. Instead it will show you how to inspect the burner can, thermocouple and ignitor and gas jet. I used a couple of special tools, you may find that you don't need them or can use an alternate.

 

Using a Phillips screwdriver, remove the two outside screws holding on the lower wind guard, then pull it straight off.

 

 

 

Remove the steel clip securing the gas tube to the brass jet. I was able to pull it off with my fingers.

 

 

Remove the two hex head screws holding the tube and ignitor/ thermocouple bracket to the main burner can.

 

 

I used a special 3/8", 1/4" drive angle socket and a long extension, you could use a regular angle "wobbly" extension. You can't easily get in there with a wrench and the screws are too tight for a flat tipped screwdriver.

 

 

Remove the little shield. Here you can see the bracket, ready to come out.

 

 

More to come...

 

John Davies

 

Spokane WA

[John E Davies]

Here is the bracket with the attached parts.

 

 

Here is the gas jet.

 

 

And the thermocouple and ignitor, on the left. The rust is typical and nothing to worry about. Make sure everything looks in good shape and the boot on the ignitor wire is not coming apart. Make sure that there is not an insect nest inside the tube, which would restrict air flow.

 

 

A look into the burner can. The horizontal divider forms a path for the burning gas, it shoots into the lower section and then turns and comes back on top. Pretty crude actually.... and not very efficient. Make sure there are no signs of leakage or birds nests.

 

 

Now for the jet. Propane and natural gas are both a little dirty. They contain impurities that will actually build up in the small jet opening and restrict it. Any appliance like a home furnace, fireplace or water heater that has a pilot can develop problems due to reduced flow through a restricted jet. The service manuals tell you to look for a "hard blue flame". A weak pilot will show as a flickering, unsteady yellow flame, and it may not stay lit. (I once had a home furnace that would blow out the pilot on windy days. Cleaning the jet cured that.) Since this water heater has an electronic ignition, you don't need to worry about a pilot light. But you do need to make sure the jet is clear. FYI:

 

[attachment file=Troubleshoot pilot flame.png]

 

The manuals tell you to NOT do what I did. Don't stick stuff into the hole and wiggle it around, since you might alter the size or create a burr. However, I have done this for just about forever and never had a problem. I use a set of tiny "jet drills" which in olden days were used by tuners to change jetting in carburetors. Carefully insert the shank of a smaller drill bit, NOT the sharp end, straight into the opening. Increase the size until you can no longer get it to enter. I found that there was some restriction and it went away as I got up to a number 61 bit. When you push in the bits, the crud breaks away and falls back into the hollow cavity inside the jet.

 

 

Here are the bits, with the sizes listed, both in the drill size and the decimal equivalent. Drill bit numbers are wacky, the smaller the number, the larger the diameter. My jet seemed to be a number 61, or 0.039" inside diameter.

 

 

Here is the package of bits. These are 35 years old and I don't know what the cost would be today.

 

 

If you use this method you don't need to remove the jet. I did, just for a look, using a 7/16" box end wrench.

 

 

And I found that the jet was stamped with its size, "61". How cool is that?

 

More...

 

John Davies

 

Spokane WA

 

 

 

 

 

 

[John E Davies]

Reassemble all the parts, but leave off the big wind guard so you can watch the fire. Make sure your heater has water in it, turn on the gas and light it off. This is what you should see.

 

 

Notice that the ignitor and thermocouple both are directly in the flame path and they glow red hot. If the flame should go out, the thermocouple will cool rapidly, send a signal to the control unit, and it will try to relight. It will do this three times. If it doesn't stay lit, the system will fault and show a red light inside the trailer. Usually it just means you ran out of propane, but it could also be a problem with one of the parts or the board itself. My board once blew out a resistor and would no longer fire the ignitor.

 

Here is a video showing the lighting sequence and what to look for in terms of the flame.

 

 

Put the last wind guard back on. I wrote the service date and jet size for future reference.

 

 

FYI smaller jets are available, but I don't know where to buy them, or which size to buy for which altitude. If you live and camp exclusively at high altitudes, like the Colorado Plateau, you should consider reducing the jet size so that the flame burns more efficiently. You can pay a shop $100 to swap it or do it yourself, it is easy peasy.

 

John Davies

 

Spokane WA