Unusual Defiance Volcano II Forced Air Furnace

[FixedGearFlyer]

My sister-in-law is trying to heat an old, 1000 sq foot, 1870's log cabin with a Defiance Volcano II forced air furnace and is having a tough go of it. I'm already helping her address the basics of cleaning the stove (can you believe the ash was over the bottom of the door opening?!), cleaning the chimney, starting and maintaining fires, etc., but I have a few basic stove questions that I'm hoping you guys can help me with.

In the Hearth.com Wiki and all the previous threads where a manual was posted, the Volcano II had secondary air control sliders on the bottom left and right, and a primary air bi-metal thermostat either on the front or the back. Alas, on this particular stove - believe it or not - there is NO primary air supply. A single lever controls a bi-metal thermostat on the front, which supplies air to the secondary tunnels/outlets at the top, rear of the furnace, just below the baffle opening. Nowhere on the front or the back is there any kind of slider, flapper, door, or spin control for primary air. I've also searched the inside of the firebox and can't find any opening for primary air.

She's obviously had a heck of a time getting the fire to do anything other than smolder unless she opens the door, which is inefficient and smokey. I was able to get a good fire going this evening by cleaning out the ash grate and pan, then using the sliding ash pan as a primary supply, but it doesn't provide much control over the draft.

Has anyone seen a Volcano II with that configuration of controls and do you have any suggestions for providing some primary air to the fire?

Interestingly, if the secondary air thermostat is set to 'High', it actually kills the fire. The draft sucks in air through the secondary tubes and into the firebox above and behind the fire, reducing the draft through the ash grate and cutting the airflow to the primary burn. So, she's been setting it on 'High' and wondering why the fire won't burn!

I'm heading back over there at lunch tomorrow to see if I can figure out a better way to get it to burn well and will get some pictures then. In the meantime, if anyone has suggestions for a primary supply other than the ash pan door, I'd be appreciative!

***Edit***

Sorry, Admins. I *swear* I was in the Boiler Room when I posted this . . . :-(

 

[begreen]

PM the webmaster if you don't get any responses.

 

[FixedGearFlyer]

Well, the mystery is partly solved.

The bimetal thermostat on the front controls the air supply to BOTH the primary and secondary air vents. As I cleaned is all out - including the ash-filled air tubes along the side of the firebox - I found a sliding draft control/diverter in each of the tubes. As it slides forwards and backwards, it controls the mix of primary air (vented into the space under the ash grate) and secondary air (vented into the top rear of the firebox) by opening and closing sliding doors. Now that we've found those and cleaned the ash out so they can actually slide, we have much better primary combustion.

The part of the mystery that has deepened is that there's no way to adjust these sliding doors without taking out the ash pan. They both have posts that extend into sides of the ash pan enclosure and I can see how the system SHOULD be set up with a control rod for each running through a hole in the bottom of each side of the furnace. But there's no hole in the furnace front and no control rod . . . I set them both to supply only primary air for now. THe reason she was seeing such poor burn performance before is that the were originally both set to supply only secondary air.

This weekend, I'll drill holes in the front of the stove and connect control rods to them so we can run the furnace as intended.

Weird. Just weird.

 

[FixedGearFlyer]

Here are a couple of quick pictures. The first shows the front of the unit with the bi-metal thermostat removed and the openings for the pre-heated air supply visible. Note that there are no holes for the control rods which are shown in all manuals for this furnace.

The second picture is the inside of the fire box. The right side pre-heated air supply tunnel is circled and you can see where the secondary air exits into the top, rear of the firebox. The 'X' is the approximate location of the primary air door that opens from the tunnel into the ash pan area to provide primary air to the fire.

I didn't get any images of the sliding "doors," I'm afraid.

 

[Dave Rostar]

I'm having the same problem but I don't know how to use this site as I just signed up. I'll try to keep in touch as either of us find answers.