Am I thankful that the safety feature worked!!

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muncybob

Minister of Fire
Apr 8, 2008
2,158
Near Williamsport, PA
Came home yesterday while wife was cooking supper. Noticed a "different" smell in parts of the house...sort of like a "electrical burn" smell...looked around and found nothing so I thought maybe it's got something to do with the roast in the oven.
Just before we sat down to eat I figure I should check the boiler since the Mrs. has a habit of not putting in enough wood for a long burn. As soon as I start down the basement stairs I sense a smell unlike what it normally would smell like. As soon as I approached the boiler I see what the cause may be and my heart skips a beat....boiler water temp is almost 210 degrees and pressure is 30 psi! Seems the Mrs. turned on the fan switch timer(WG calls it a purge timer) to load it up earlier and the switch stayed stuck so the fan never turned off. Fortunately Wood Gun shuts down at 210 degrees so water never boiled and pressure relief valve never opened so no mess to contend with. We will not rely on that timer switch anymore unless we will stay there to be sure it winds down to zero and shuts down ...will just use a thermostat to call for heat and force the boiler fan on if it's not already running when it's time to reload.

Anybody have similar experiences?? Do all boilers have this built in protection to avoid boiling the water? What would have been the potential disaster if the unit never shut down and water got to over 212 degrees?
 
Not all, but most gassers on the market today have an electronic control with overheat shut down built in, along with several other controls if you choose to use them. I know Wood Gun is still relying on a couple aquastats for temp. control. Also, most installations incorporate an overheat dump zone in one form or another.

Funny how our senses work. Feels hot always works, however "smells hot" and "looks hot" also work surprisingly well!
 
Good to hear that everything worked as it should, although I would check your pressure relief valve. I believe it should have released pressure at 30psi. My WG pressure relief is set for 30psi and when I filled the WG for the first time I pushed the pressure up to verify it would release. (just a little water on the floor) Sometimes these things stick.
 
The pressure was just about 30 so I think it just had not reached the release point...thankfully!
Fred, I should have known something was up when I washed my hands at the sink and noticed how hot that water was! There are 3 aquastats on the boiler. None are set over 180...so how would they shut it down @ 200+ degrees? Is there something else that sesnes the potential boiling point and shuts it down?
 
You know, I just don't remember. I had all the wiring schematics in a filing cabinet that I cleaned out a couple years ago. I had a friend help me with the oil mode lock and his method of designing was to make a copy of the drawing, cut out the components and lay them on a large piece of paper and then add his own components to the circuit in between the original components so I had several copies. That timer for the fan might possibly bypass any controls.

I had a serious overheat once which was caused by a small stick of wood that apparently got in the way of the combustion air flap and held it open. No control except for an overheat dump zone would have worked in that instance.
 
I had the same problem with the timer switch on my E-100. It quit working shortly after I received it. The timer switch bypasses the aquastat at the rear of the stove but not the high/low temp cutoff switch on the front left corner. The high/low cutoff should be set around 205 although the temperature could creep up after shutdown depending upon your setup. The high pressure was not caused as much by the heat but by your expansion tank being undersized, you should never see pressures that high. Need to calculate the amount of water in your system and resize the tank to handle water from about 50 degrees to 210 degrees. Several websites have programs that will do this. My boiler runs about 15 to 18 lbs pressure regardless of the temp (I've been as high as 220 but not on purpose).
 
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