Amtrol HWM/Boiler failure

Mark Hunt

a situation like this a few years ago.(Different boiler make)

The contactor on the aqua-stat arced and welded itself shut. The boiler ran non-stop the entire time the customer was away. He returned to burst copper finned baseboard. The pressure relief valve had been jammed into a 2x4 stud and could not relieve the pressure. Once the water had boiler out of the system, the base box melted and the boiler block dropped onto the burners extingushing the flame. It was so hot that the linoleum was scorched 2 feet away.

I wish you luck with the insurance company. They do not like giving back the money you paid them.

Mark H

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David Cameron

Continued boiling of Amtrol tank

I am not a heating dummy, but I am perplexed as to how a boiler/hot water maker combo could fail like mine did.

We have a Weil McLain boiler and a 41 gallon Amtrol hot water maker.

The system was working fine before we left the house for two weeks. We came back to find our house at about 100 deg F, and 100% humid.

The radiant floor heating zones were off.

The boiler had boiled the water in the water maker, essentially steaming out the whole house. Water condensed everywhere it could find cold air, which was essentially in every wall.

Why didnt the safety device on the boiler kick in and save the system? Is it true that under no circumstances the system should boil? The temp safety trip on the boiler was set to 180 deg F. From what I read, it is supposed to turn the gas off when the temp is higher than 180.

Isnt there a PSV on the boiler circulation water as well?

I did not actually see steam come out of the PSVs on the hot water maker or boiler, as I turned off the gas supply so I could get within 30 feet of the boiler without being scolded by the heat.

There is extensive mold and moisture damage to the house, and I am really afraid that insurance is going to find a way around this one.

Any tips/tricks from past expereiences?

Dave Cameron

Josh_10

What I am perplexed by is the DHW exchange rate. Even if the aquastat was welded shut the indirect will never exceed the temp of the boiler.

What is your boilers aquastat set at? Or was it the boilers aquastat that failed?

We always install a manual reset high limit on every install we do. Both boiler and domestic hot water. You should think about doing that. It is alot cheaper than replacing your equipment, not to mention your lives!

Mark Hunt

My case


involved the boiler aqua-stat. No indirect involved here.

Mark H

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David Cameron

The temp on the water maker was set pretty high - 5 out of 6. There was no specific setpoint on it, just off though 6, with 120 deg at position 3.

Even if the water thermostat was faulty, shouldnt the temperature safety in the boiler have throttled back the gas?

The pipes that fed the exchanger in the hot water maker had that black "foam like" insulation around it. I said "had" becuase the majority is in a puddle on the floor where it melted and dripped down. That is how hot the boiler circulation got. The pipes also have that fine rust on them which I have only seem on high pressure steam lines...

Also there was no moisture damage with 20 feet of the boiler. That is how hot it was around the boiler, even though that is where the steam was being released.

What is the PSV on the standard water maker set at? I would imagine it would have to be around 100 psi, which would make the temperature required to boil the water above 300?

Thanks for yout insight. This is going to be quite a di$a$ter financially if the insurance company wont cover the mold damage.

Dave

Mark Hunt

T&P valve


Temperature and Pressure relief valve: 150psi/210 degree F.

Something had to have kept the aquastat relay pulled in for this to happen.

Any power surges while you were away?

Mark H

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David Cameron

> Temperature and Pressure relief valve:

> 150psi/210 degree F.

>

> Something had to have

> kept the aquastat relay pulled in for this to

> happen.

>

> Any power surges while you were

> away?


I am not sure of the term "Aquastat" but the safety device on the boiler was set at 180 deg F. That is the one with the little thermocouple that comes out of it, and is wired to the boiler controller. The device has a little thumbwheel to set the temp.

When I finally was able to get close enough to the boiler, the circulation temperature of the boiler was over 230, at about 50 psi. That was over an hour after it had its gas supply cut off.

Thanks for all your insight. It seems as though two devices would have had to fail to cause this condition.

1) The thermostat on the hot water maker was continually asking for heat for that "zone", thus keeping the boiler alive.

2) The thermostat on the boiler did not sense the overtemperature condition and cut back the firing.

The end result was continued steam release from the system, and no stopping of the boiler firing. And I cant wait to get my gas bill!

Another symptom was that the cold water regulator that feeds the boiler circulation seemed to have a pinkish fluid on it, almost looked like automatic transmission fluid. Not sure if it was related. Too bad I didnt have my camera with me, or I could have posted some photos.

Dave Cameron