Wood Furnace Help

[sefh3]

OK guys I need your help. I'm have a wood stove Grizzly (I believe) from TSC hook up to a fuel oil furnance. The wood stove runs for about 30 sec then shuts off. Both stoves have blowers on them. I have the wood stove hooked into the plantum and a 6" duct going the the chimey. The problems that I'm having is that the stove runs for a short period of time then shuts off and I go through alot of wood in the winter. Do I have it hooked up wrong or do I need another thermostat because I have two blowers? Or do I eliminate one of the blowers and just use the one off the furnace? Thanks

 

[ericjeeper]

Oh my

Let me give it a try. The 30 second run could be caused by the plenum temp sensor.. seeing to much heat. so it cycles to cool off the plenum. Now are you sure you have it wired properly to your stat?
Photos of your ductwork would help to.. so we can determine which blower or both need to run. Thanks

 

[hanniedog]

Had a similar set up in garage. There should be a thermostat for the wood burner to trigger the combustion blower. A seperate stat to tell the fuel oil furnace to run. The main blower on the wood burner will cycle off and on depending on the temp of the stove. If you have the wood burner really cranking the plenum heat sensor will tell the fuel oil blower to run. They do tend to burn a fair amount of wood. Hope this helps some.

 

[hockeypuck]

What type of thermostat are you using and if it is a round honeywell with a mercury switch make sure the attenuation is set properly. I have had the problem when they were used on a oil burner. Try taking the two wires on your wall thermostat and cross them . If the wood buner stays on, you know it is thermostat problem.

 

[sefh3]

I will get some pics by this weekend and post them to how it is setup. I didn't do the install so it is hard for me to explain.

The thermostat is a old round one. If I don't have a fire and run just the fuel furnance it works just fine so I don't think the stat is bad.

 

[sefh3]

Had a similar set up in garage. There should be a thermostat for the wood burner to trigger the combustion blower. A seperate stat to tell the fuel oil furnace to run. The main blower on the wood burner will cycle off and on depending on the temp of the stove. If you have the wood burner really cranking the plenum heat sensor will tell the fuel oil blower to run. They do tend to burn a fair amount of wood. Hope this helps some.

What I was think was placing another stat next to the existing one and set it for 70 degress hooked up to the wood stove and then use the existing one and set to 60 degrees so when the fire is low it will still heat the house off the fuel oil.

 

[laynes69]

If its an older wood furnace, it should have a limit control in the back of the unit. Also is the woodfurnace has a thermostat then it should have the auto draft, or forced draft. The reason it is coming on and off so quickly is if it has a limit, its set to come on and off too close together. I have mine set for 135 to 140 on and 80 off. It will run forever with a fire in it. As far as the thermostat goes, thats a good reason for you to burn alot of wood for a forced draft, especially if the thermostat calls for heat. I put a digital heat thermostat right beside my propane furnace thermostat and ran the digital to my forced draft. I rarely use it, but either way whether its on or off if the house falls below a certain temp, the propane furnace kicks on. The nice thing about the digital thermostat for the wood furnace is, you can set it to be accurate, and if you don't want to use it, then just switch it to off. I keep my propane furnace set for 67 and I average 76 most of the winter with the wood furnace going.

 

[sefh3]

Ok I took some pics of the set up. It is a Clayton sorry for the mistake.

 

[wmscott]

your fan control on the back of your wood furnace is too close to the heat, try moving it up near the top of the duct. I had the same kind of problem on my wood furnace. You may also need to adjust the settings on the fan control also, but dollars to donuts, the fan control is just too close to the fire box. It gets way too much heat, then the fans goes on and cools it off and off goes the blower and then the cycle repeats. If you move the fan control up into the duct work, it will not see the heat until the furnace has heated the air in the duct, then when the fan goes on, it will blow the hot air from the wood furnace into the duct work. So the fan control will not be suddenly cooled as it is where it is mounted now. The only reason the furnace makers mount the fan controler on the furnace is because they don't supply the duct work where it should be mounted, and they don't have to supply you with as much wiring to reach the higher placement. Better built wood furnaces that I have seen on the web, normally have the fan control placed up on the duct work where it belongs.

Oh yes, you should also check to see that the air isn't being pushed backwards through the wood furnace by the blower in your fuel oil furnace. That can happen if it has a higher static air pressure then the wood furnace blower which has the smallest blower they though they could get away with using. If that is the case, you may have to set your fuel oil furnace blower to a slower speed. If it is already at the slowest speed, you have a problem. You would then probably have to install a larger blower on the wood furnace, or change your hook up all together.

 

[laynes69]

The 3 tubes coming off of the propane furnace are going into the back and side of the woodfurnace. Then I have 3 8" ducts coming off the top of the woodfurnace into the main ductwork. This is series. The only thing that could be a problem is if you have ac, then you would need to duct it to bypass the woodfurnace in the summertime. Also if you aren't going to burn wood in the fall or spring, then also bypass the woodfurnace because it takes alot of heat to heat up the woodfurnace to push the propanes heat through the house. If the fire goes out into the night, then the gas furnace kicks in. This is a temporary setup, but we heated this way last year. I want to replace the 3 8" ducts from the LP furnace with an 8x18 trunk, and cut a hole in the top of the woodfurnace to use a 20x20 plenum. This will help reduce any back pressure in the system.