Has anyone's OWB had a meltdown

[stltreedr]

I stoked my Aquatherm 275 SS last night about 8 o'clock. The draft fan had just cycled and the temp was at 175, pressure about 5 psi. Stocked it full, it got down to about 14 degrees last night.

I walked outside this morning to find smoke and steam pouring out of the wood shed, took a flashlight down and saw that my temp guage had melted, steam and smoke pouring out of the expansion tank, not the relief valve. I shoveled the coals out of it and sprayed it down with water to cool off. Then I had to go to work.

The ash door was closed, everything seemed fine last night, water temp in the house seemed about normal to the touch. Did my water pump fail? not a good day.

 

[Uncle John]

Maybe got too much air due to high wind?
High wind blowing across stack can cause a suction.
With a pump failure is still would have shut off the blower.

 

[stltreedr]

The blower was off this morning. Too smoky to get behind and look at it though.

 

[Kemper]

I had the Aquastat fail on mine and boiled out about 10 gallons of water, I turned it down to 140 and it would still heat the water to 175, so i called and Natures Comfort sent me a new one and all is well now...

 

[phantomblack]

Man, do I ever understand where you are coming from. I had my central boiler 5036 boil over last winter in Mid Feb. When mine happened I woke up at about 2:30 to visit the john, and wandered over to look at my boiler temp gauges in the house. Seen my gauges at 207 on the outlet and 207 on the inlet.

I turned on all heat zones in the house and ran outside to find steam and smoke pouring out of the boiler, and the propane dragon now running.... I pulled the fire out of the boiler, and waited for it to cool down to figure out WTF happened. Then heard a bang from the door, the dampener solenoid had hung up and stuck open. Bad part was that due to the heat the pump was cavitating and seized up also. I ended up installing my backup pump, getting the boiler cooled off through the thermal load of the house, replacing the dampener solenoid, adding about 30 gallons of water back into the system and getting a new fire going all between 2:30 and 4:00 in the morning..... What a PITA that was.

Generally I have found now that a boil over, or the boiler running a little warm is something silly or easy, but the collateral damage is not. Mine cost me a jug of water conditioner and a replacement cartridge for my pump. All due to me not taking the time to clean the door solenoid with some WD-40.:bang:

Good luck, let us know how it turns out.

 

[vinced]

I'm 99% sure that you didn't close the door all the way. I have an older model Aquatherm 145 (smaller sized then yours) and boiled it over once because I didn't latch the door all the way. It didn't melt my gauge, but I had to replace it because it maxed out and wouldn't come back. I also had to replace the water pump impeller because it melted and about a 30" piece of PEX line that goes to my underground lines. The only other thing that might have happened is for some reason the air flap on the blower didn't close, but these are designed to close when they fail or power is cut off. Don't ever spray it down with water. You could cause it to stress crack or even cause it to warp. If your pump failed I doubt it would cause it to boil over. It would just get alittle hotter then the aquastat setting but it would still smother the fire. As for the pressure reliefs (there should be 2 in the back on the top) you should check them every year by manually cracking them to keep them working. I think from the heating and cooling of the stove they have a tendency to stick. I hope everything works out for you and let us know what you find. My Aquatherm is a 1995 model and I've had it for 6 years and it is still going strong making me money every year. Good luck!

 

[showrguy]

Man, do I ever understand where you are coming from. I had my central boiler 5036 boil over last winter in Mid Feb. When mine happened I woke up at about 2:30 to visit the john, and wandered over to look at my boiler temp gauges in the house. Seen my gauges at 207 on the outlet and 207 on the inlet.

I turned on all heat zones in the house and ran outside to find steam and smoke pouring out of the boiler, and the propane dragon now running.... I pulled the fire out of the boiler, and waited for it to cool down to figure out WTF happened. Then heard a bang from the door, the dampener solenoid had hung up and stuck open. Bad part was that due to the heat the pump was cavitating and seized up also. I ended up installing my backup pump, getting the boiler cooled off through the thermal load of the house, replacing the dampener solenoid, adding about 30 gallons of water back into the system and getting a new fire going all between 2:30 and 4:00 in the morning..... What a PITA that was.

Generally I have found now that a boil over, or the boiler running a little warm is something silly or easy, but the collateral damage is not. Mine cost me a jug of water conditioner and a replacement cartridge for my pump. All due to me not taking the time to clean the door solenoid with some WD-40.:bang:

Good luck, let us know how it turns out.

i have a different brand OWB, but everything that happened on yours also happenened to me/mine a couple a years ago..
my fault though, the solenoid was getting really noisy, so i shoulda replaced it before the meltdown..

 

[vinced]

I had the Aquastat fail on mine and boiled out about 10 gallons of water, I turned it down to 140 and it would still heat the water to 175, so i called and Natures Comfort sent me a new one and all is well now...

Thats possible, but Aquatherms are pressurized so they won't boil water off unless the pressure gets up to 30psi. I replaced my Honeywell aquastat with a digital one (I believe it is a Ranco) it is very accurate and has more adjustment of the temp differential.

 

[stltreedr]

I haven't looked at it, but you're telling me that the annoying noise that happens periodically is a solenoid going out and I will probably find the draft flap stuck in the open position....I am such a dumbass. I will keep you all updated with pics tonight when I'm not fearing for my life from a boiler explosion.

 

[stltreedr]

I ended up installing my backup pump, getting the boiler cooled off through the thermal load of the house, replacing the dampener solenoid, adding about 30 gallons of water back into the system and getting a new fire going all between 2:30 and 4:00 in the morning..... What a PITA that was.

.

Serious rep for doing all that in the middle of the night.

 

[Kemper]

Thats possible, but Aquatherms are pressurized so they won't boil water off unless the pressure gets up to 30psi. I replaced my Honeywell aquastat with a digital one (I believe it is a Ranco) it is very accurate and has more adjustment of the temp differential.

Possible? Yea... when the aquastat does not shut down the draft blower when the boiler reaches the desired temperature it's gonna boil water out the vent until it runs out of wood...

 

[jreimer]

The same thing happened to me a few years ago with my old smoke dragon. I hadn't latched the loading door properly and by morning it had boiled off a good 40 gallons. It looked like a steam rocket shooting out of the expansion tank! Melted the solder on the dry wells, destroyed the pumps and aquastat. The worst part was taking it all apart and repairing it outside when the temperature was hitting -40F without the windchill! My cordless drill didn't even want to turn.

 

[vinced]

Possible? Yea... when the aquastat does not shut down the draft blower when the boiler reaches the desired temperature it's gonna boil water out the vent until it runs out of wood...

No vent on a Aquatherm, just pressure relief valves. I'm not saying a Aquastat can't fail, I'm just saying if it were a common problem there would be a few companys out of business. Never thought about lubing my damper hinge. I'll have to go do that. It has had nothing done to it for over 15 years. Most of the time when a boil over happens its from operator error. Just saying...

 

[Kemper]

No vent on a Aquatherm, just pressure relief valves. I'm not saying a Aquastat can't fail, I'm just saying if it were a common problem there would be a few companys out of business. Never thought about lubing my damper hinge. I'll have to go do that. It has had nothing done to it for over 15 years. Most of the time when a boil over happens its from operator error. Just saying...

You're setup is different than mine, i don't have any pressure relief valves, my boiler has a 3 inch pipe that sticks up through the top of boiler with a rubber cap and a float valve so i can see if the water level is full, it is essentially open to the atmosphere.

When the aquastat failed, it just kept feeding the fire with the forced air draft, I would think they could come up with an additional emergency shut off for overheating? I could probably figure out something myself ....

 

[stltreedr]

The Culprit

I had to go home and check it out at lunch. Draft flap is stuck open, melted about 12" of pex line. I already ordered the solenoid and the temp gauge. I hope that's all that's wrong with it. Dammit this sucks. Once again though, I got my answers from AS. There's really alot of knowledge on this site. Pics for you all to make fun of.

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[phantomblack]

good luck

 

[vinced]

I had to go home and check it out at lunch. Draft flap is stuck open, melted about 12" of pex line. I already ordered the solenoid and the temp gauge. I hope that's all that's wrong with it. Dammit this sucks. Once again though, I got my answers from AS. There's really alot of knowledge on this site. Pics for you all to make fun of.

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Any idea what caused it to stick open? Did the solenoid fail? Did the hinge stick and not let the flap close. Just curious has I never had a problem with mine and thought it might be a good thing to have a spare on hand.

 

[greendohn]

I spaced it one evening, left the door open on my WoodMaster, it boiled out about 15 gallons of H2O. Luckily the "distraction" that called me away from the stove in the 1st place had allowed me to only throw a couple of pieces of wood in there..
A guy down the road has a Hardy and he has struggled with creosote keeping his damper open. I guess he has had a couple boil overs because of this and it has drained his well dry, at least once..I keep preachin' the virtues of seasoned wood.

 

[stltreedr]

after reading all the responses, I assume the solenoid is bad. It had been making noise since almost new. Which is one of the reasons I didn't mess with it. I actually thought it was the fan motor, and replaced it once, only to find that it wasn't making the annoying, buzzing sound. I closed the flapper by hand and it felt 'gritty' inside, but then it freed up. I already ordered the parts, I'll let you know how it goes, hopefully they will be here today. About $120 so far for the solenoid, temp/pressure gauge, stick of pex and a couple gator bite fittings. I guess it could be worse. Then again, there might be more wrong with it. I put about 38 gallons of water in it last night before thinking, hey, it's gonna be cold tomorrow, I think I'll stop putting straight water in this. Still not sure how much water it will take.

 

[stltreedr]

A question for all of you though, is there any way to put an alarm of some sort on this so If temp gets too high I will know it in the house?