Wood Furnace Question

Thanks for any help in advance.

I have an older clayton wood furnace and need to figure out how to stop the fan from running after the fire has burn out and just have more overall control of the house temp, I have attached a picture of a similar unit.



It has a 12 inch duct coming out of the unit and it connects to my return ducting to heat the house. It has an induction blower on the front just like the unit in the above picture with a damper at the bottom and the top damper, all like the picture above. It also has a fan on the back of the unit with a filter like the picture below.



The unit is in the basement and I have a thermostat upstairs that controls the induction blower, I usually leave the blower unplugged because I don't find it useful or I am not using it correctly, lol. The fan box in the back of the unit is controlled by a limit switch, like the one below.



This issue I have is that when I wake up in the morning the fan has been blowing all night after the fire has gone out. Does that mean that my low cut off setting is not low enough or too low. I wish there was a better way to set this up, maybe the fan should be on the thermostat and not the induction blower. I don't have a lot of experience with wood furnaces and would like to have more control over the unit when it comes to heating the house and to keep the fan from running all night reducing its life span.

Thanks,
Nathan

STIHLY DAN said:

Is your switch pulled? Making it in the manual on position.

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Nope

JRHAWK9 said:

good call. I believe pulled out is auto and pushed in is manual. If it's pushed in it will run all the time and ignore what you have it set at.

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LOL I wished it was that easy.

brenndatomu said:

So now I'm confused, is this the small draft fan on the front, or the larger duct blower on the back that you are concerned with?
If its the duct blower, then yeah, like @STIHLY DAN said, you have a fan control/limit switch issue...but if its the draft fan on the front you are talking about...its running because the thermostat is calling for heat...but the fire is burnt out because you either didn't load enough wood, or the furnace chewed through it too fast...which is the more likely scenario, pretty common on those cheaper wood furnaces, they tend to have a large appetite.

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Nope, not the forced draft blower on the front. It's the fan blower on the rear that is running constantly when the fire is burnt out.

STIHLY DAN said:

$100 fix... temp speed controller.

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Do you mean the fan center or limit switch?

supertech1979 said:

Do you mean the fan center or limit switch?

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supertech1979 said:

Do you mean the fan center or limit switch?

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I attached a picture of what my fan center looks like.

I am also wondering if the fan limit switch is kicking the fan blower back on because the fire is burning out and it is going all the way around to the limit setting and kicking the fan back on. Thoughts?

So I have 2 thermostats in my house. One controls my electric heat and air and the other is the ones that controls the forced induction blower on the front of the wood furnace. Interesting enough, when I get the house around 70 degrees with the wood furnace then let it burn out, the stove is cool but the house is still warm (68 degrees) degrees then the blower fan box is off. The electric furnace is set to kick on at 65 degrees. Could the wood furnace be wired to my electric thermostat somehow and cause that fan to shut off when the electric thermostat is above 65 degrees? I highly doubt it but though I would ask the question since I don't want to just throw parts at this and would like to diagnose it first.

Ill take some pics of the wiring tonight. I will research on how to test the limit switch.

Thanks to all
Nathan

I have attached pictures of the wiring.

supertech1979 said:

I have attached pictures of the wiring.

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Can someone with more experience look at the wiring and let me know if it looks correct?

brenndatomu said:

So you have electric heat coils in your AC air handler for heat? (or an "electric furnace" with AC coil...same thing more or less)
Maybe the electric heat is back feeding hot air through the wood furnace, which is kicking the wood furnace blower on?

FYI, its pretty hard to diagnose electrical issues from a few pictures...almost need an electrical/wiring diagram, and then you need to be able to check stuff with a meter too, since we can't be there.

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Agreed that you are limited to knowing by looking at the pics. You bring up a really good point through, there isn't anything from keeping the heat from the heat pump from pushing the heat back through the stove and out the chimney. There is a manual backdraft damper on it but I never have messed with it, just always left it open.

brenndatomu said:

Well, it isn't going up the chimney, but the heat is not just going up into your living quarters either...and electric heat is too expensive to be heating the basement with it! So there is a manual damper on the ductwork between the 2 furnaces? If so, close it after the wood furnace is cold...but gotta make sure its open when you light the fire again though!

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Yeah I totally messed that up, it can't go up the chimney, lol. Yeah its a round 12 inch duct coming from the furnace that connects to the supply side of the house ductwork. I'll try this over the next few days and see what happens.

supertech1979 said:

Yeah I totally messed that up, it can't go up the chimney, lol. Yeah its a round 12 inch duct coming from the furnace that connects to the supply side of the house ductwork. I'll try this over the next few days and see what happens.

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Well I hate to throw parts at this issue but I may have to. So I turned my electric heat pump off for the last two days so that there couldn't be any interference from it. Each day I awoke without the fan being on so it would seem it works fine. The house temp both days was around 68-70 when I got out of bed. The temp has been in the mid 20's to 30's at night so before I got to bed I loaded up the furnace full and turned down the dampers (I know, I know). I wake up to a warm house and the fan not running which is what I want but it still doesn't make sense to me.

Here is the two scenarios:

-Load the furnace at night but not full, wake up and the house is cool and the fan is running.
-Load the furnace FULL at night, wake up and house is warm and fan is not running.

Unless I am wrong, which I probably am, the limit switch should turn the fan off when the temp gets to and below 100 degrees in the fire box, right?

If that is correct, then there is no way that the temp isn't dropping below 100 the last 2 days with only coals. Is it possible that since the temp of the house is warmer that it keeps the fire box warmer too which keeps the fan off the last 2 days?

If I am correct about the limit switch then I will replace and see what happens.