Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers with NON EPA-Certified Models Only => Home Made => Topic started by: mabrandes on November 12, 2015, 03:13:06 PM
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My wife and I recently purchased a home/shop and the previous owner built a home-made OWB to heat the shop with. He's showed me how to use it and now I'm looking to improve on it somewhat, from a control perspective. I'm going to over go over the design and then my proposed changes. I'm looking for some recommendations for the new control parts I need. Any help appreciated.
The wood furnace itself is pretty straight forward design with ~100 gallon water jacket. The water flows from the OWB into a remote ~300 gallon water tank (thermal mass I suppose) It then flows from there into a ceiling mounted blower which draws the air over 2 car radiators. At this point the water returns back to the OWB. The unique element here is the remote water tank. The furnace
itself is housed in a small shed on the back of the shop. The remote tank is located in the shop in a corner about 20ft away.
The control system is very limited and this is where I need to improve on it. In the present state, a wall mounted thermostat controls the ceiling blower and the furnace blower. The circulation pump basically runs all the time. The furnace blower does not have a flapper. There is no mechanism that can control the actual water temperature. He did add in an "overtemp" circuit. In the event that the water temp reaches ~180 degree's, it triggers everything to come on... pump & ceiling blower basically in an effort to reduce the water temp.
Here are my proposed changes...
@ Furnace:
- Add a flapper/solenoid to furnace blower to clamp down the air going into the furnace when in idle mode. (Based on what I've read so far it seems the basic premise is when the water needs heated, use the furnace blower to get the fire hot and once the water comes to temp, clamp down the fire.)
- Add aquastat to engage furnace blower/flapper when water needs heated.
@ Remote Water Tank:
- Add aquastat that will turn on circulation pump when temp falls below preset temp. This will essentially take the water from the water jacket at the furnace and circulate it into the tank.
@ Wall thermostat
- Thermostat should turn on ceiling blower + turn on circulator.
RECOMMENDATION NEEDED:
Do the above changes make sense?
I need two aquastats, one @ furnace and one @ water tank. I 'think' I need low-limit aquastat with differential setting. Can someone
recommend what I would need? It looks like the Honeywell ones are most popular from a Google search.
Thanks!!
Matthew
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180 isn’t that warm, Heatmaster G series come from the factory to shut off at 180 with a 190 hi temp limit. I’ve run my homemade waste oil boiler as hot as 195 before.
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Ranco controllers are a good and real common. Johnson Controls A419 is similar but with a couple extra features and cost a little more.
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Thanks RSI. Now that I know what to search for, I'm finding several options.
Ranco controllers are a good and real common. Johnson Controls A419 is similar but with a couple extra features and cost a little more.