Wood Bolier Overheat Protection

Ron Schroeder_3

was installed for one of my new clients. An uninsulated range boiler was installed in the attic. It was isolated from the heating system by a one inch zone valve held shut under power. The spring motor wound the valve open when power was lost. A little antifreeze is in order of course.

If you have the necessary head room you could install the range boiler like an old fashioned compression tank with similar results. The coolng water would not be as cool as that coming from the attic but you also would not need antfreeze.

Hope this helps.

jim post

encouraging gravity flow

I am piping a Tarm Wood Gasification boiler and need to allow for the dissipation of heat to prevent a thermonuclear meltdown of boiler in the event there is a power loss while a load of wood is burning. I plan to pipe a normally closed zone of 3/4" copper baseboard near the boiler to accomplish this. Do I need to slope the baseboard element in any particular manner to encourage gravity flow around this loop. Would it be more effective if I ran the element vertically?
Thanks for any insight provided.

jp

Ruthe Jubinville

Tarm boiler

On a power loss, the fan stops and the fire very quickly dies down. We usually have one of the larger zones start circulating if needed.

jim post

Circulator Power

On power loss....what causes your circulator to circulate? I want some of it whatever it is. :-)

hr

I'm not sure

That a loop of 3/4 baseboard, gravity driven, would dump much heat? I've heard, from Tarm owners, that they do wind down fairly quickly when the blower stops. It's really not that much different from the aquastat satisfing with a load of wood inside.

Be sure the door and gasket seats well, this is a common source of overheat problems with many wood burners. Need to close off the O2 almost completely.

Some of the other Euro units I have installed use a loop of pipe mounted to the top of the boiler that runs potable water from the well to handle overshoots. A much more positive means than a gravity bb loop. Higher delta t and better conduction transfer, vs conduction air currents next to a already hot boiler space Although not a power outage control, unless you don't mind the water running till power is restored.

A 12 DC pump and a car battery with a trickle charge would be another option. This could keep the heat on in the building also, for a short power outage.

If you must use bb, get a piece of commercial steel fin tube with 1-1/4 or 1-1/2" pipe size. The larger bore would thermo siphon better.

I've heard of folks using a regular automotive radiator also.

hot rod

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tls_9

Use

A normaly open control valve, as fred said, one that opens on power loss. Obtain one (or more) of the old "B" style cast iron radiators in the ceiling of the basement and pipe as you would for a gravety system. A large freestanding cast iron radiator on the first floor will also do.

The best way to hande this situation is to take the time to learn how to properly hand fire a sloid fuil boiler. This takes patience and time. This is an art form virtualy lost to mankind.

tom

hr

Good point Tom

regarding operator error You'd be surprised how often homeowners fuel a boiler and forget to close or latch the door. Talk about a run away. You'd need a lot of cast radiator iron to disapate that output

There is a learning curve to burning wood. Some owners pick it up quickly, others not.

I have one "pot head" customer that steams his about 3 times every season. Think he lights one up every time he goes outside to fuel up and loses track of reality

hot rod

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jim post

Power-loss overheat protection

Thanks for the suggestions. Losing power is not something that most people can predict. That is the reason for my question about gravity flow when power is out. It's not a very common occurance but one that needs to be accounted for. I agree there will be learning curve associated with this choice of heating appliance. By the way, there is another overheat control to handle operator error that opens heating zones and engages the circulator on overheat if power is available.

Thanks again.

jp

tls_9

you could use

a high limit aquastat that opens on temperature rise with all zone valves Normaly Open so they open when the stat does.
end switches on the zone valves will activate the pumps.

tom