Waterheater leak at drain plug

[flymerc]

About two weeks ago I replaced a damaged H2O heater drain plug.

After replacement it was leak free until this afternoon. I removed the leaking drain plug and found a hairline crack in the plug.

I have had issues with the H2O heater tripping the fault indicator on the control panel as well as heavy shooting at the exhaust.

My question is, what caused the new drain plug to crack? Over temp? Over pressure?

It's plastic, thus I installed it about a 1/4 turn past finger tight, and it was leak free for the past two weeks, so I'm 100% sure I did not over torque the drain plug.

The pressure relief valve seems to operate OK when I manually operate it so I doubt that is the problem.

I'll need to check H2O temp at the sink Facuet to verify an over temp issue.

Anything I may be overlooking?

Thank you in advance.😁

[maynardjw]

My guess is you got a defective plug. I would not think plastic would crack do to high temp. Has the burner tube been cleaned? Take a compressor or air can and blow out the burner tube and burner chamber as this can cause soot issues. It could also be too much fuel to too little air which could require an adjustment but cleaning the tube hopefully will solve this. Poor fuel to air is probably the reason for the fault as well. The unit will only try to start a couple of times before it shuts off. Just my thoughts. Good luck

[JohnB]

What you are describing with the plug and the soot seems to point to 2 different issues.

1. The heavy soot and the fault indicators on the KIB panel may be part of the same issue. The fault indicates a flame sense problem when running on LP gas. And that is all it indicates is on LP gas. On startup, it tried to light 3 times, it did not get the flame sense feedback and then shuts down on safety lock out. OR the burner was burning and then the flame blew out and lost the flame sense feedback. To reset the fault you turn the LP gas toggle switch at the tank panel off then back on and and it will try and light again.

If the system has air in the gas lines from not being turned on in a while, then you may get 1 to 2 false trip as the air escapes but should then not come back again.

But in your case that heavy soot is a air/fuel mixture that it not right. Have you ever run the heater on gas before? Trying to find out if this has done this since you owned it or it work right a long them and then just started?

Right now your system is most likely pretty sooted up. Lets look at a few pics of one not all sooted up.


A close up to show what I am going to talk to


At the left is the gas valve, has the coil and 2 red wires going to the ECO sensor. On the end of that gas valve is a brass nozzle. And in the end of that nozzle is a very fine tip. You need to be carefull no dirt or soot gets blown into that nozzle tip and do not poke it with anything like a small pin etc.

Right after the nozzle is the slotted circular tube that is the air mixture adjustment. You can see this one about 1/4 open. For this burner that was the air need to create a nice blue flame when burning and not a mega load roaring burn. There are several things that can cause the heavy sooting, the simplest is the air shutter is very wrong all the way to the gas jet being out of location to the end of the bruner being bent.

Rather than me typing all this, see here in our files section on the service manual
Sunline Coach Owner's Club - Sunline Owner's Files - Atwood 2007 Service and Training Manual

See PDF page 29, (Atwood page 18 ) through PDF page 31 (Atwood page 20) for all the things that can cause heavy sooting and how to adjust out of it.

To de soot everything first, turn the 12 volts off to the heater and turn the LP gas off first. I would take the burner out of the heater and take the gas valve, gas line and nozzle all still connected out of the burner to not get any of the soot into the gas jet/orifice. You can see here is separates out pretty easy. As long as the mounting bracket is not all bent up, it will go right back where it is supposed to when the put the screws back in.



Atwood tells you if the nozzle/jet/orifice is dirty to soak it in isopropyl alcohol.

Once the burner tube is out then you can brush it or blow it out. Clean the big heater tube that goes through the tank and comes out the vent area of the cover. It may be all covered with soot in there. Check the electrode gaps and the flame spreader at the end of the burner tube it is not bent from the prior owner.

When you get it all back together, with water in it have the cover open and someone inside turn it on and you may have to tweak the air shutter very slightly from that 1/4 open position. Note what yours was set at before you take it apart. Take pics before hand in case you forget something how it was.

2. The cracked plug, I think this separate from the sooting issue. See this pic


The plug in the center is the original Atwood nylon plug. The other fittings are nylon fittings from other sources. You can see the Atwood plug is longer and there is pipe compound on the threads. I use Teflon tape on the plastic threads and I do a slight amount of wrench turning. Not a lot but more then finger tight.

I do not know if you had the Atwood plug to start with. Have a look. Other nylons plugs rated for hot water service can be used too if needed. I have not had a plug crack but did over time have the threads stretch to where it will not seal up. Then I just change the plug, put new tape on and it seals. Do not put a metal plug in, reasoning being cross threading the tank by accident. The nylon plug is cheap if you cross thread it. The tank is not so cheap...

If you do not have time to deal with the soot, leave the LP gas toggle switch off and you can use the 120 VAC electric side of the heater until you can get to the gas system.

Hope this helps

John

[Sunline Fan]

Yeah, agreed with the above. Cracking plugs are not common, and I torque mine down more usually.

The feeder line to the burner tube has a little slider piece of tube on it, with vents in it. As mentioned above, this determines the air/fuel ratio. It's very easy to adjust, and similarly very easy to get out of adjustment if you don't realize it. See here on how to correct:

[Draughty]

I design in aluminum all the time and using a metal plug could result in the metals seizing together!
This would be very bad!
I am assuming however that your Atwood tank is aluminum like mine ..

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[flymerc]

Have you ever run the heater on gas before?

Trying to find out if this has done this since you owned it or it work right a long them and then just started

Yes we have been operating the LP gas option with the H2O heater for the past 4 weeks. It has been sooty from the get go.

I will check the vent tube for a 1/4 gap and check for a blue flame this evening.

As for the leaking drain plug I do find it odd that when I purchased the last drain plug, it was packaged with two plugs. This tells me the these plugs may be a weak point by design. or folks mess them up installing them and need a spare???

To be sure, until I can figure out what is going on I'm getting a few to have plenty of spares.

I can say that the drain plug was leak free until I operated the H2O heater with both gas & electric. Perhaps there may have been an over temp condition caused by both heat elements operating at the same time?

As a precautionary step, I think I will only operate either LP gas or electric at a time and not both simultaneously.

Thank you all for your good info, it has been a great help!!!!

[flymerc]

Something else i found very odd. When I removed the leaking drain plug (using a 7/8" socket) I was unable to start the new drain plug into the threads of the tank.

I attempted to re-install the original plug (the leaker) and wasn't unable to start it into the threads of the tank.

I purchased a 3/4"dia./14 thread tap to chase the threads in the tank. I know I buggered up the threads slightly the first time i removed the drain plug as it broke off in the tank and I was forced to use a screwdriver as a chisel to remove the reminents of the plug.

Hopefully I can chase the threads and install a new plastic drain plug and be good!

[Draughty]

Ouch... standard 3/4 threads are different from pipe threads as pipe threads are not straight sided but a bit tapered so they 'plug' the tapped (and also tapered) hole into which they are placed.
Teflon tape may be your only help if that is the problem..

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[flymerc]

Not to worry, the tap I purchased is a 3/4" NPT tap.

[Draughty]

That is excellent!
Some do not know that there is a difference...

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[flymerc]

I bought the wrong size tap.

I got a 3/4" NPT tap and need a 1/2"....joy, joy.��

I was able to install a drain plug, although it leaks, at least we have water until I get the correct size tap.

I adjusted the gas mixture that was full open to 1/4 open. Had my wife turn on the gas and ignition, and it lit off and was burning OK until something went wrong.

By wrong I mean a gas leak ignited and fire was all over the inside of the box.��

Nothing burned up, all looks OK after extuingishing the fire by shutting the gas off.

I have no idea what happened to induce a gas leak. I have to assume It's a bad gas valve at this point. I need to purchase a L.P. gas leak detector and start down yet another rabbit hole of troubleshooting.

[JohnB]

Originally Posted by flymerc

By wrong I mean a gas leak ignited and fire was all over the inside of the box.��

Nothing burned up, all looks OK after extuingishing the fire by shutting the gas off.

I have no idea what happened to induce a gas leak. I have to assume It's a bad gas valve at this point. I need to purchase a L.P. gas leak detector and start down yet another rabbit hole of troubleshooting.

I'll start with the easier response first, using the LP gas and the electric at the same time on your vintage of water heater, I would not necessarily connect that with the drain plug leaking. On your 2004 camper you have the newer Atwood control system. Meaning the same T stat that shuts down the LP gas also shuts down the electric at the same time. The prior vintage water heater did have 2 seperate T stats and they could be out of calibration of each other making one hotter.

Thinking through this, since both are controlled by the same T stat, they "should" of been shut down at the same time. Using both will just get to the T stat temp faster. The only thing that might let one burn longer is a fault in the control board meaning the board allowed one to run several minutes longer.

OR on the electric the power relay stuck on in a delayed fashion. (not highly likely but not impossible) Relays usually burn on (contacts weld shut) or the magnet coil burns out and nothing energizes. So in one failure mode the electric would not ever shut off and in the other mode it would not turn on.

OR the gas valve stayed open to later drop out. It is double solenoid valve for added safety. Meaning 2 gas valves in series with each other to increase the odds of shutting off when it was supposed to. However if one valve gets stuck open all the time, then the system has no feedback to tell half the valve is in fault. So then there is only 1 solenoid actually shutting the valve down and if that fails open then the burner will not shut down until the ECO shuts it down which is a lot hotter water.

Since you seem to think there is a connection that both gas and electric running at the same time may affect the drain plug, it may be but would be caused from a higher temp of the water which will create a higher thermal expansion which builds pressure when the faucets are shut off.

Checking the water temp on electric is a good place to start. If it shuts down at approx 140F and does not get a lot hotter then at least during this test the element relay and board is working correct.

Now to the next problem, your problem of the fire... that is not good... And the air shutter being wide open which seems it may have been since you got the camper.

Do you have any thoughts on where the fire was burning at inside the compartment? Looking for a location to help point to a fitting or device was leaking that was burning. There actually is a thermal fuse that will melt open and shut down (or try to) all the power to the electric element and the gas valve if that thermal fuse gets hot enough. That thermal fuse is located in series with the T stat. In this pic it is inside the clear tubing that then connects to the T stat under the foam cover.


Once it melts open internally it has to be replaced. It's a one shot deal. A question would be, is there one installed? The prior owner may have had corrosion issues on the connections which does happen and removed it. If yours does not have one, it should be replaced. It is sort of the last ditch effect for the system to shut itself down if a fire starts.

If the gas valve stuck open, the burner should of just run like normal other then getting the water very hot.

There may be a leak in the gas piping fittings or the gas valve body . There are a few things to help see if they are leaking. Using gas leak solution on the fittings and look for bubbles.

The other is a gas pressure test. See this post for some help on this. There are 3 gas tests to insure the system is working correct. They are talked about in this post. http://www.sunlineclub.com/forums/f7...cks-10981.html

If you fail the leak check, then the hunt is where is the leak? After doing "all" the easy get to fitting checks with leak solution, the hunt gets more complex. I had to unhook and plug off devices when no fittings showed up as the leak to keep eliminating what was good while looking for the leaks. Yes there may be more than 1.

I have had the stove regulator leak, the water heater gas valve leak through both valves and the main changeover regulator become faulty and not regulate the pressure correctly when a large call for gas occured. I thought for sure I did a post on this, just I cannot find it. It was on my T2499 and we sold that so it had to be before 2009. I'll look some more. I do have the pics though.

The stove regulator leaking


The gas valve micro leak. Leak solution bubble on the end of the gas nozzle tip


The regulator that had to be changed. It would go up to 14" to 15" WC and stay there if I recall right during the large call for gas.


Hope this helps. Please report back you findings. We too learn with you.

Thanks

John

[enormiss]

Maybe blocked gas flow, did you clean out the tube?

[Janalee]

Did something build a large nest/hive/web in that tube? Blockage and/or flames could develop I would think, and not necessarily be a gas leak. I have seen caterpillar nests on fire that can cause a scare. We have had problems with all of the above at times.. Each time we put our water heater into use, I would blow out that tube. I always carry a small diameter "bottle" brush also..those little varmints get into everything. I also tap my 'chimney tube' and then make sure there is no collected debris on the burner itself to ignite..JMHO, of course..I always look for the simple things first...

[flymerc]

Today I installed a new gas valve, and thermostat set for good measure.

The L.P. gas fault light came on occasionally and the thermostat set and gas valve had some corrosion , thus I thought it prudent to replace them.

As for the gas leak that caused the fireball , well I'm embarrassed to say I found the gas line nut loose. They say you can't fix stupid, but stupid can be burnt in a fireball.

I found the sliding mixture adjustment tube full open. This is what was causing the soot. Thank you John for the heads up on checking that first!

I adjusted the mixture tube to 1/4 Open and the flame is quiet and blue.😁

So far so good with the drain plug not leaking. Although the other two drain plugs did not leak for a week or two after installation. Time will tell.

[Draughty]

Now that the water heater is working I realize I should check the fuel air mixture as well!
Thanks for the heads up... remembered after getting it running that the PO said they melted the electric element so I will be looking for one of those eventually though for now I am happy with hot water even if it uses LP.

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[JohnB]

Glad you are up and running on gas.... Thanks for reporting back.

I'll add a comment on the corrosion on the gas valve. Unless Atwood changed something, the gas valve is bare aluminum. There is no coating at all on it and as such it is very exposed to corrosion.

If you notice this gas valve is black.


The way it got that was I masked off the brass gas orifice and the solenoid coils and painted the exposed aluminum. The only reason it is black is that was the color of left over spray paint I had at the time. That pic was from our prior T2499. The T310SR we have now I also painted, just I used silver on that one as that was the color I had.

Point being, if you plan on keeping the camper a good long time, some time in the not too distant future consider masking off the valve and putting a light coat of paint on the exposed aluminum. It will ward off 98% of the corrosion. I did mine on the T310SR in late 2007 right after we bought it. It was not fuzzed up yet. Today it still looks new.

I cannot say that for my other 2, 2004 campers I have that were not painted within a few years of being new. Bare aluminum exposed to the outside world even if behind a sheet metal flap is not a long lasting setup.

Hope this helps

John

[flymerc]

Good call on painting the gas valve John!

Also, Now that I've replaced the gas valve and ECO/Thermostat set, the heater still throws a fault once in awhile.

Could it be possible I have the ECO and Thermostat switched (installed in the opposite position)? That would be an easy fix.

If not, then I would guess a LP gas issue first, then maybe a ignition issue.

After the camper is completely good to go again, my troubleshooting skill set will be sharp!

[JohnB]

Originally Posted by flymerc

Also, Now that I've replaced the gas valve and ECO/Thermostat set, the heater still throws a fault once in awhile.

Could it be possible I have the ECO and Thermostat switched (installed in the opposite position)? That would be an easy fix.

If not, then I would guess a LP gas issue first, then maybe a ignition issue.

I have not tried moving the location of the T stat and the ECO. I always just had the ECO closer to the gas valve as that was where the wires went. I'm not seeing the switching of those 2 locations to be the problem. The tank temp is going to be really close to the same the small distance they are apart.

That said, the setpoint on those 2 switches are very different. Using the T stat which open at 140F to the gas valve in place of the ECO (which trips at 180F) is a problem. It would give you a gas fault whenever the water met temp as the gas valve would drop out and the ECO if it was in the T stat timing would not be open. I'm assuming you might have the location switched but not the wires?

The fault alarm on the KIB tank panel "only" means a flame fault. For some reason the flame sense feedback was lost when it was not supposed to be. Now need to go down that trail and see what comes up.

Some possible choices that can create a gas flame fault.

1. Make sure you have a good ground. To the heater and on the heater. The DC negative can be a bad actor with corrosion.

2. The electrode which when heated creates a millivolt signal the PC board picks up on. It does double duty, sparks to start the flame then once started sends a signal to stop the ignition. If the electrode has shifted location, it might not get hot enough to send the signal all the time. While you are checking, check the electrode gap too. Gap is 1/8" for the electrode

3. Make sure the electrode does not have a cracked porcelain insulator. If it jumps spark in the crack it will not light right all the time and that creates a flame fault.

4. Wire connection on the electrode. Make sure it is not corroded and tight.

5. PC board push on terminal strip dirt/corrosion. Heavy dirt or corrosion happens on this PC board strip due to the place it lives in. Pull the wire connection tab off, clean the strip and then push the connector back on and off a few times to make sure it scratches in a good new connection. Since that strip also powers the gas valve, if the valve drops out when it is not supposed to you will get no flame sense feed back as there is no flame when it is supposed to be.

6. If the gas valve wire on the ECO valve is not making good contact, that would drop out the gas valve when it was supposed to be on and create a flame sense fault.

Have you been able to figure out:

A. The fault light is on a cold start up, never got flame when it was supposed to.

B. You had flame, it was burning as it was running and then the fault happened, means lost flame sense signal but gas was burning and shut down on saftey.

C. It was up and burning and then lost flame and a few seconds later got fault light.

D. You found it happening on A, B & C...

Knowing which issue you are fighting, lost the flame or never sensed it narrows down the hunt.

Hope this helps

John

PS I have had more issues with the system not starting, meaning no gas valve clunk and no sparking at all. This issue is generally corrosion on the T stat and or thermal fuse signal line. The PC board was sent to run but the T stat and safeties where open circuit due to corrosion on the connections.

[flymerc]

The ground at the H2O heater is good.

It lights for a few seconds then goes out. Thus leads me to think it may be gas related.

The regulator and hoses at the tanks look old.

I guess I'll need a gas pressure gauge to see if. The H2O heater is getting the proper gas pressure.