Hand Fired Coal Wood Boiler

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coalcrazy
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Location: chester county PA

Post by coalcrazy » Sat. Nov. 27, 2010 6:38 pm

hello everyone, anyone can chime in on this one! is a 10% of total BTU output dump zone enough using 1 cast iron rad rated at 13,000btu at 200f enough?hand fired boiler rated at 12000btu. I feel maybe more rads are necessary? what do you think? a stoker maybe but handfired not sure.

 
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Yanche
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Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

Post by Yanche » Sat. Nov. 27, 2010 10:34 pm

Almost impossible to answer. It's really a rate of heat transfer issue. Suppose your boiler temperature is creeping up for some reason. It's increasing the pressure and the safety pressure valve will soon blow. You want to avoid that. So you need to (1) avoid firing the boiler any more and (2) get rid of heat. How fast do you need to do it? Fast enough that the pressure doesn't build to the safety trip, usually 30 psi. OK. You have so many gallons of water at close to flash point temperature. You need to move it to some colder place in a hurry. That colder place could be your radiator or a big cold tank of water. Obviously that big tank of water could rapidly reduce the boiler water return temperature. What's the surrounding temperature of the radiator? How quickly can the surrounding air remove the heat from the radiator? What size pump do you need? Well a fire engine pump would surely work. Anything less in size will require some heat transfer analysis using this basic equation:
Now the real challenge ... Design a system that doesn't need electric.

 
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AA130FIREMAN
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Post by AA130FIREMAN » Sat. Nov. 27, 2010 11:03 pm

Do you have a large main zone for the house you could use as a dump zone ? It may overshoot the temps a little but would work alot better than pushing an elephant into an elevator :lol: Why overshoot one room when you could do a larger area and not notice a heat wave 8-) I use the fancoil in my a/c ductwork as the dump zone in winter, same BTU output as the stoker and set at 205, will knock it down 5 deg in about 3 min.


 
coalcrazy
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Post by coalcrazy » Sun. Nov. 28, 2010 7:45 am

thank guys, its my brothers boiler van wert multitherm simplex ocf 120 hooked to hot air via coil. smaller well insulated home, powerful boiler, too much heat! we have the dump hooked to coil now house gets to 95f at times. good thing is its very slow to over shoot, it does build heat just slowly. we may add one more rad. coalcrazy

 
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AA130FIREMAN
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Post by AA130FIREMAN » Sun. Nov. 28, 2010 8:43 am

95 is a LITTLE overshoot :shock: , open them windows. If it's a hand fired, he'll have to learn to fire it down some, smaller coal=less draft. The BTU output of a radiator or fancoil is based on the ambient room temp and the water temp. The output of the 13,000 BTU radiator if the water is 200 in a room that is 200, would be 0 btu's.

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