Drolet Tundra II / Heapro

[Highbeam]

I wasn't referring to the moisture in the flue. I was more referring to the cold metal firebox upon lighting a fire and the warm/moist air from the freshly started fire condensing on the cold metal firebox before the furnace body is up to temp. I'm assuming there is a certain level of insulation (ceramic blanket) in between the firebrick and the firebox metal. If moisture ever gets trapped in between this insulation and metal firebox I'm assuming there is going to be some level of rust happening. The colder the fireboxes metal jacket is the higher the chances of water getting trapped and causing rust. This would be my worry with pulling in very cold outside air and running it through the air jacket of a warm air furnace.

Maybe. Does anybody have fiber insulation between the firebricks and firebox steel? Even if this were the case it gets mighty hot at the actual firebox.

Fire is at over 1000 degrees. The ambient air at 25 vs 65 is just not important to the firebox but I do believe it will cool the heat exchanger quicker. Enough to cycle the blower.

 

[brenndatomu]

Does anybody have fiber insulation between the firebricks and firebox steel?

Tundra 1 does...

 

[Highbeam]

I feel like you’re imagining a wood boiler with perpetually 33 degree water jacket around the firebox. A warm air furnace is not like that. The still air around the firebox will quickly warm until it’s hot enough to be whisked away by the blower. Cold air is much less able to steal heat from the firebox than water. Imagine quenching a hot piece of metal in a bucket of water compared to waving it around in the air.

 

[JRHAWK9]

I could very well be wrong, but it's a concern I would have for sure. Doesn't take much moisture at all to get trapped and to start the rusting process. Once it starts, it's over with.

I would definitely make sure my low limit snap switch was set appropriately to keep the temps up inside the air jacket as much as possible.

 

[maple1]

I don't think I would be too concerned. It's an issue with boilers but they have liquid cooled fire boxes.

 

[AnthonySr]

Well guys, we haven't started any updates yet. I have saved all of the info concerning the blower mods & hookup details. I did purchase a duct return for the blower that reaches the ceiling to pull warm air into the blower housing
Instead of off the cold floor. I also picked up an IR gun to check the rpm of the blower for reference. I monitor this website daily & have year round to pick up any new tips from other owners of the new type II drolet or heatpro models.
It's been to much to cold in NW WI. To fool around with this stuff, I'm hoping to get started in April..

Jack snipe did you ever figure out a solution I seem to have the same problem

 

[jacksnipe]

Jack snipe did you ever figure out a solution I seem to have the same problem

Nope not yet, I'm getting ready to start in next week hooking up the cold air return to the blower box. I'm installing ducting at the ceiling level to pull warm air into the blower housing, instead of drawing cold air off the floor. I had to fashion up a sheet metal part the fits outside the furnace filter. The weather is starting to warm up so the results won't
Be fully determined until this fall. The next step if req'd is to mount a fan control for the blower. I'm thinking the hook up
Might be seat of the pants, but the diagrams that were supplied by the forum members provide some important details. Note: The Heatpro wiring is a bit different than the tundra because of the probe in the plenum..

 

[AnthonySr]

It was about 40 today and the only way I can get it to blow real high is to have the damper open and feed it huge amounts of wood. Have you tried there technical hot line?

I am considering building walls around it and having the ducts go through the wall
to preheat the air before it gets to the unit any thoughts?

Anthony

 

[AnthonySr]

It was about 40 today and the only way I can get it to blow real high is to have the damper open and feed it huge amounts of wood. Have you tried there technical hot line?

I am considering building walls around it and having the ducts go through the wall
to preheat the air before it gets to the unit any thoughts?

Anthony

I think we figured it out but it took a little cheating. I took about a 12 inch piece of 6 inch duct
And scribed it to the exhaust flue off the back of the furnace on the horizontal on the top we sealed it off with a cap then we put a hole in it and stuck in the probe.

Until I figure a better way this seems to be working perfectly of course we are bringing the furnace temps down but my barn is warming up just fine. Can’t wait to try it next year in the cold weather.

 

[JRHAWK9]

I feel like you’re imagining a wood boiler with perpetually 33 degree water jacket around the firebox. A warm air furnace is not like that. The still air around the firebox will quickly warm until it’s hot enough to be whisked away by the blower. Cold air is much less able to steal heat from the firebox than water. Imagine quenching a hot piece of metal in a bucket of water compared to waving it around in the air.

I see you posted in this thread "over there". This is exactly what my concern would be when using the OP's furnace in such a cold area. Not sure what his issue is or what caused it after 8 years (I think it was), but I can see it being exaggerated if he would have been trying to heat a building up from 25° all the time. Man, that is some THIN metal used on those BK's.

 

[Highbeam]

I see you posted in this thread "over there". This is exactly what my concern would be when using the OP's furnace in such a cold area. Not sure what his issue is or what caused it after 8 years (I think it was), but I can see it being exaggerated if he would have been trying to heat a building up from 25° all the time. Man, that is some THIN metal used on those BK's.

View attachment 226866 View attachment 226867

Unlike any current furnace, the bk firebox mostly runs very cold with no flames and intentional gooey tar coating everything since the firebox itself is below the condensation point. The cat stays hot and eats up the smoke to make heat. The steel should have been thicker to prevent rust through or maybe there was something else wrong there.

This is completely different than a noncat stove or furnace that runs firebox minimum temperatures several times higher to maintain low emissions.

I have a bk and that rust through concerned me.