Wood Add-on Furnace fix or replace?

[Nicole575]

We have a Russell Stove add-on furnace that was installed in 1981. Not sure the last time it was used before we bought the house. It is designed with an after burner to increase efficiency (I have the manual). We had a new stovepipe installed and into a dedicated chimney. Here is my long story:

We burned for about 4-5 days around the clock when it we had sub-zero temps and loved it for the most part. We had some issues with smoke in the house. I traced this back to the air intake for the afterburner. When the blower fan is running it is drawing air out of this intake and pulling in smoke which then blows through the heat vents into the house. When I blocked the air intake...no smoke!

It warmed up and we didn't use the wood burner for about a week. Then the temps dropped so I fired it up again. I went to add wood at 4:00 AM and noticed black liquid dripping from the stove pipe. I think I know that is creosote and that our stove pipe is likely installed upside down if it is dripping out. We used fire extinguishers to put the fire out and haven't burned since. I believe the build up occurred so rapidly because I am running slow burn fires without the afterburner.

Finally! Here is my question: is it worth it to have something made to extend the location of the the intake for the afterburner away from the blower fan and would it draw enough air to work, or should we just replace the whole furnace with a newer model? There are literally no experts anywhere near us, I've looked. I'm adding a photo of the air intake, you can see the black drip on the fan that sits right below the air intake. (Our thermostat is not connected to the fan in this photo).

 

[aokpops]

I don't know were to begin or what to say . There are some major issues of air handling going on the furnace will get hot fast an destroy it self with the blower unhooked . Not being able to see more for some reason your not getting enough return air .

 

[Deleted member 150358]

Google brings up a copy of the manual FWIW. The hosts a forbidden site here.

So the smoke is getting pulled out through the afterburn tube by the blower?

 

[Streblerm]

I think you may have a couple things going on. I’m also unclear if the blower in the picture is a forced draft blower which would blow on the fire directly when there is a call for heat from the thermostat or if that is the blower that pushes air around the furnace into the duct work to supply heat to the house. It looks a little big for a draft blower but maybe a little small for duct blower. More info on the system would be helpful.

I suspect your wood supply moisture content is too high. It sounds like you’re new to wood burning which everyone is at some point. My experience is that if you did not personally witness the wood being split and stacked for at least a year then it is probably nowhere near ready to burn. If you’re seeing that kind of creosote build up after a few days of burning regardless of the secondary air being on or off that is a sign of overly wet wood. Wet wood will smolder and make a lot of smoke which is more likely to get a smoke smell in your house. Blocking off the afterburn may aggravate the creosote problem but it shouldn’t cause it.

Another problem could be if your blower for the duct is pulling air from the same room as the furnace. If this is the case then the blower will fight the chimney draft pulling smoke into the house. Especially with a smoldering fire which will have a weak draft. Opening a door or window in the room while the furnace is burning would be an easy way to test this out.

My first move would not be to modify the furnace although I wouldn’t rule it out. A little smoke smell with an older furnace isn’t out of the ordinary. I would still monitor it and if you don’t already have one get a carbon monoxide detector. I would go buy some kiln dried firewood bundles so you know it is dry and see if that is a part of the problem. If you’re still getting a smoke smell then you should either hook the duct blower to a cold air return from outside the room or provide outside air for combustion, or both. Combustion air and cold air return should not come from the same room.

Replacing the furnace with the same setup could lead to the same problem. For an almost 40 year old furnace it doesn’t look like it’s had much use. It makes me wonder if the install was faulty from the beginning.

 

[NSMaple1]

Think there's some confusion above between draft blower & duct work blower.

If the draft blower is pulling smoke in, that should not get distributed to the house. It should go up the chimney.

 

[NSMaple1]

Finally! Here is my question: is it worth it to have something made to extend the location of the the intake for the afterburner away from the blower fan and would it draw enough air to work, or should we just replace the whole furnace with a newer model?

Can you hook a pipe onto the inlet of your draft blower and extend that away from the furnace instead?

 

[Nicole575]

Thank you for all of your replies! Everyone has been very helpful. Yes, we are new to heating with wood and appreciate all of the kindly advice in this forum.

This is a ductwork blower that blows through the heat exchanger on the wood burner into the ductwork of the house. We feel a little trickle of warm air in the vents until our main furnace kicks on. We supplement with wood heat so we use less propane. We don't have a draft blower. We are careful to open the heat exchanger flaps if the blower is not on so the furnace does not overheat (as per the manufacturers instructions). The furnace likely was not used much, at least not in the past 6 years (previous owner). The fan looks new because we had it cleaned and repaired.

Our wood is problematic. It is several seasons old, but has been out in the weather so it is "wet" from rain. We have been drying it inside as we get ready to use it. We'll work on drying the wood in the barn for next year. We might have to buy wood for next winter as we season what we cut this year from our property.

The ductwork blower sits right below the air intake for the afterburner, so they draw from the same room and within inches of each other. I like the idea of some kind of piping on the blower intake to change where it draws from, I hadn't thought of that.

So, this week I will be having the chimney cleaned, buying dry wood, and attaching a tube to the blower intake to change the airflow. At the end of the day, this may have been a poorly designed furnace that we replace, but at least we tried.

 

[moresnow]

Have you considered that running your dedicated forced air home furnace at the same time as your wood furnace may be causing a furnace competition for available combustible air between the two systems? Have you tried running just the wood furnace alone as a test? I would. Your home's main forced air furnace may be pulling air/smoke backwards through your wood furnace secondary air intake causing your smell. It may have zero to do with the wood furnace heat distribution fan that appears to be mounted in its stock location.
On another note. Drizzling wet creosote does not indicate dry wood by any means If anything it looks to be miserably wet. Take a few splits that have been indoors for 24 hours. They need to be up to room temp for most moisture meters to read accurately. Re-split them and check the freshly exposed face of the split with a moisture meter. Don't check the ends or old dry face's. Those readings mean next to nothing. Get a meter with 2 prongs. You are looking for 20% moisture content or less ideally. Get a meter at any box store or hardware. They are inexpensive. Not trying to overwhelm you with info but hoping you get things functioning correctly. Guessing you will love the wood heat if you get everything dialed in.

 

[NSMaple1]

Do you have a manual? I can't imagine them intending for the duct blower to be pulling air in, right below the combustion intake like that. Usually a duct blower is on the back & combustion intake is on the front. So wondering if there is anything in the manual about needing to install a ducted return onto the fan intake?

Also thinking as above - the wood pretty well has to be too wet to make liquid like that.

 

[cat10ken]

Box in that fan with duct work and attach it so it is drawing from the cold air return line. If it is a closed system it won't effect the combustion air.