Vermont DownDrafter

[Kiff]

Just bought a house with a Vermont DownDrafter wood furnace. I am new to wood burning heat, but very excited about it. I am having a lot of trouble trying to find any information or operation how to's on the stove. I seem to have the basics down, but the flue temps seem to always stay very cool(200-250), even when heat output is great. To get the flue temps up I go through large amounts of wood and heating the house way too much.

My other question is the brochure that was left with the stove says a loaded wood box should burn for 14hrs. I can't seem to get 6 out of it when I go to bed and dampen it right down. in the morning there is only ash left.

Any basics or info on the stove would be great!

 

[Grisu]

How do you measure the flue temperature? What kind of pipe do you have (single-wall, double-wall)?

What species wood do you load? Softwoods won't give you as long of a burn time as hardwoods.

Any pics?

 

[Kiff]

It is a single wall 8" and I am using a magnetic gauge. I have been experimenting with maple, arbutus and fir.

Another question is that if anyone has and UL number for the stove or any sort of certification numbers that would help my insurance process and fair bit!

 

[Grisu]

Interesting design. Looks like someone took a stove and put some sheet metal around it to fashion a wood furnace. That stove certainly looks older than being UL-listed. You can try to remove the shell in the back and look for an UL-listing label. If there is none your insurance will most likely consider it an unlisted stove. It will be up to them whether they accept it or not.

Outside temps of single wall flue pipe are about half of the actual flue gas temperature. Thus, you have been running the stove at 400 F to 500 F in the flue. That should be sufficient to keep the flue gases above 250 F when water vapors start condensing on the flue walls. What kind of chimney do you have outside?

 

[Kiff]

the chimney is a 8" masonry. Would the gauge already take into account the difference from flue temp and outside stove pipe? it shows "burn zone" to be around 275 F to 550 F. Above that is the "Danger Zone"

The sheet metal around the outside is insulated and definitely not factory, and routes a duct into the cold air return for the forced air system. Seems to work fairly well. The water coils for the boiler are a huge bonus as well.

 

[fbelec]

just to be sure take your stove pipe thermometer and put it in a 400 degree oven and see what it says. it won't be spot on but should give you a idea where your at.

 

[Kiff]

I had the oven set to 400*F. The thermometer read 600*F. So it is a fair amount out.

 

[fbelec]

time for a new one. that tells you you were running it to cool. just make smaller fires but hot ones and the creosote will be in check.

 

[Kiff]

It tells me I've been running hot correct? If the oven was at 400 the thermostat should have read around 800 correct? This is if the thermostat is set to compensate for stove pipe temp to flue temp. If it is not then yes I've been running things cold. The smoke out the chimney looks to be very light, sometimes almost hard to see.

The frustrating thing is burn time. With the wood box absolutely stuffed with mostly fir and some alder the longest burn time I've gotten is around 6 hours. Nothing left except for ash when the fire burns out

 

[fbelec]

if it is a magnetic thermometer it is surface temp. if it is a probe it should be the same calibration except a true reading of what is inside and not the cooler pipe. thats how it was explained to me. if your getting 6 hours out of a softwood you are doing well. see if you can get a load of hardwood and see what that does.

 

[Kiff]

So if the magnetic thermostat is giving a reading of 300*F the flue temps are around 600*F? I took my laser thermometer and was checking the stove pipe. The magnetic one was reading around 300 and the laser was showing 300-325 F. So not sure why the stove test gave a strange reading.

Forgive me if this seems like I'm beating a dead horse, but the magnetic thermostat shows the "burn zone" at the 300-500 F area. If that is surface temp then my flue temps are way too high if they are in fact double the surface temp. Then I should be aiming for a surface temp between 150-250 F

The only reason I'm hoping for a longer burn time is every morning I need to relight the stove and when I come home from work.

 

[fbelec]

i hear your problem. i have to do the same thing but for a different reason. my stove is to big for my house so i have to give it time to cool before the next fire or we'll all melt in here. if you run your stove between 300 and 400 stack temp you should be fine for the chimney. if you run it cooler than that it will continue to cool as it goes up thru the chimney and could get down below the magic number and condense and tar up your chimney. if your chimney is a outside of the house chimney you might want to lean towards the high side because it will cool off quick. my chimney is short and outside and i have problems even at 350 stack. if i ran my chimney temp up higher i'd be overfiring my stove. it's a fence i'm walkin just hope i don't fall off.