Water heater problem

[DWalt]

As we have so many here familiar with a wide number of household problems, I have one.

I have a propane water heater (about 6 years old) which is not heating. The pilot light will come on and stay on, but the main burner will not ignite. I have fiddled around with everything possible but no luck. Is there a fix I can try before I need to buy another gas control unit? - see below

 

[bamabiker]

You will probably need a new control but make sure the knob is not broke or loose(not likely) and is turning the control to On.
Also might tap on the control with something hard.
I can't see the bottom of the water heater but some of them have a reset on a sensor and it kind of looks like yours may have one. The white thing in your picture between the orange wire and pilot tube, does it have 2 wires hooked to it?

 

[hittman77]

This day and age 6 years may be the life expectancy of the entire water heater. Throwing parts at it may be a waste in the long run.

 

[nodpete]

Sounds like the thermocouple is shot. Easy fix.

 

[bamabiker]

A lot of newer water heaters have the burner enclosed and it draws it's air from around the bottom of the water heater and up through a flame arrestor. This area and the arrestor needs to be kept clean so it gets enough air. The sensor lets the WH know if it's not getting enough air and the temp around the burner gets too hot. It will shut down the water heater.

 

[cballman]

Like bamabiker said air flow around the entrance to the bottom is a must. Had a plumber "NOT ME" come by when we had problems. Cleaned out the area and made a larger air hole in the bottom. Now not a propane heater but Natural gas. Good luck.
Also the thermocoupler unit might also be shot also. Both problems go hand in hand.

 

[bamabiker]

Thermocouple lets valve know a flame is present to ignite gas when the valve opens. If the pilot stays on the thermocouple is doing its job.

 

[Maddog 521]

Another vote for the Thermocouple. They are easy to replace.

 

[DWalt]

"If the pilot stays on the thermocouple is doing its job."

I figured that if the pilot light was staying lit, which it is, then the thermocouple should be OK. Am I right? Or is it still something which I should replace?

"I can't see the bottom of the water heater but some of them have a reset on a sensor and it kind of looks like yours may have one. The white thing in your picture between the orange wire and pilot tube, does it have 2 wires hooked to it?"

There are two wires leading from the gas controller to what I am guessing is a thermal cutoff switch (arrestor??) at the bottom. Likewise, I assume that is not a problem as the burner never comes on so it cannot open (or close?) as the temperature cannot get too high. As there is no source of electricity, I don't know how that thermal switch would control anything. Can someone explain how the thermal switch (arrestor?) works and if that could be a problem? Would replacing it possibly help? Someone else told me to turn the controller temperature dial over to "vacation" which will supposedly reset the controller's internal thermostat, then turn it back to a normal setting. I tried that, but it did not help.

I know the gas control is a fairly expensive device (I had to replace one about 10 years ago, which looked much like this one, and as I remember it was about $150 at that time), so I would like to avoid replacing this one if possible. I looked through the instruction manual that came with the water heater for possible assistance, but that didn't help any - it just said to contact a service provider.

 

[bamabiker]

Thermocouple should be OK? - yes
The thermal cutoff switch is what I called a sensor. Some of them have to be reset once they shut off the WH.
Is there a small button in the middle of the switch between the 2 wires? Don't really look like a button.
It's been a while since I reset one so I don't remember if the pilot should be lit or off when you push the reset. Or if it makes a difference but seems like I remember it does.

What kind of WH is it? Brand?
Some makers have youtube videos on repairing their WHs.

 

[doublesharp]

I recently had a natl gas wh installed and there is a long narrow filter that does around the perimeter of the tank. Got to get down on your hands and knees and carefully pull the flixible plastic screen out, clean it good and then thread it back in. Plumber said do it twice a year. Looks like it's going to be a pain inasmuch as it's something else to keep up with but it didn't look to hard.

I asked why and he said often wh are located near clothes dryers and lint and dust was a problem. I've had mine about 2 months and haven't tried to clean mine yet.

 

[bamabiker]

That filter/screen should be kept clean because the dust, lint, etc. cuts down on the air coming in under the WH. There is also a flame arrestor at the bottom of the WH under the burner. Sometimes it will get dirty and need cleaning.
If these get too dirty the temperature around the burner gets too high and the WH shuts off.

 

[DWalt]

I plan to pull out the burner and check to see if the burner gas orifice might be plugged. Not sure how that could happen, but it's at least worth checking. If the orifice is not plugged, then I have to believe I will need a new gas control valve. I will check the thermal cutoff switch also. I did find out that some of them have a little button that needs to be pushed to reset them if triggered.

 

[mtgianni]

"If the pilot stays on the thermocouple is doing its job."

I figured that if the pilot light was staying lit, which it is, then the thermocouple should be OK. Am I right? Or is it still something which I should replace?

"I can't see the bottom of the water heater but some of them have a reset on a sensor and it kind of looks like yours may have one. The white thing in your picture between the orange wire and pilot tube, does it have 2 wires hooked to it?"

There are two wires leading from the gas controller to what I am guessing is a thermal cutoff switch (arrestor??) at the bottom. Likewise, I assume that is not a problem as the burner never comes on so it cannot open (or close?) as the temperature cannot get too high. As there is no source of electricity, I don't know how that thermal switch would control anything. Can someone explain how the thermal switch (arrestor?) works and if that could be a problem? Would replacing it possibly help? Someone else told me to turn the controller temperature dial over to "vacation" which will supposedly reset the controller's internal thermostat, then turn it back to a normal setting. I tried that, but it did not help.

I know the gas control is a fairly expensive device (I had to replace one about 10 years ago, which looked much like this one, and as I remember it was about $150 at that time), so I would like to avoid replacing this one if possible. I looked through the instruction manual that came with the water heater for possible assistance, but that didn't help any - it just said to contact a service provider.

Two wires go to a temperature sensing switch, also occasionally called a roll out switch. See if their connections are soldered or just connected with crimp on connectors. The purpose is to prevent flame rolling out and coming into the house from a plugged flue. They complete a circuit with the voltage generated by the thermocouple = 30 Millivolts. One MV is 1/1000 of a volt so any crud, corrosion or verdigris build up and you drop 5 millivolts. Typically this will knockout the pilot circuit so this should not be the problem.
In an extreme hard water area the calcium and insulate the temperature probe into thinking the water is still warm. This usually results in wide temperature swings but still hot water when it does fire.
If I were there I would pull the thermostat dial off and turn the small knob all the way on. If it doesn't come on then the temp section is toast. The danger with doing this is if you do not reset it you will have a steam bomb in your compartment. You must immediately return it to it's former position , whether or not it fired. A new heater will have a few more safeties on it than yours does. You will pay for each of those and the electronics will fail long before the tank does. This extra $$$ will save you $25 over the lifespan of the heater and reduce fuel usage and greenhouse gas emissions.
If I had a boiler I would put in a sidearm water heater rather than mess with them. This uses the boilers water to heat domestic hot water.
You may find a shop willing to sell you a used control valve for half of new with no warranty. The height must be exact to fit your burner as the burner tubes are extremely difficult to adapt.
Before doing anything I would take an 8" or 10" crescent wrench and thump the side of the control opposite the gas entrance. Valves stick and that might loosen it. If it dies start a valve fund of $15 a week because this won't last, just get you better prepared to buy a new one.

 

[Ivan the Butcher]

If you do go with a new control valve. You should put in a new thermal Couple, but THEY ARE NO LONGER UNIVERSAL! Be sure the new Couple it the right one for the Valve. Some even have LEFT HAND THREADS!

Ivan

BTW The photo looks like the unit is much older than a mere 6 years, it that is the case, you may have a humidity problem causing undue corrosion.

 

[DWalt]

Thanks for the tips, I will try them. This water heater is in a trailer house at a separate location from my home, so it will be maybe several weeks before I can get back to it. The wires to the roll-out switch do have crimp-on connectors.