1975 defiant

[Tpaull]

So, as some of you may know, I’ve been in the market to replace my jotul firelight 12. I just bought a 1975 Vermont castings defiant for 50$. Seems to be in good shape. Wondering if there are and quirks or problematic things I should be looking for before I let this thing thing burn all winter. No cracks internally and it seems to be in good shape over all.

 

[peakbagger]

Time to get yourself a copy of the manual.

Is it a two-piece fireback or one piece?.

Very key to good operation is proper size chimney flue. These need a 8" flue pipe, trying to reduce it to 6" or connecting it to inadequate chimney is asking for problems. Preferably an interior chimney with two stories of height exiting near the ridge pole. These need good draft to run right assuming the internals are not plugged.

The key to the Defiant is a hidden chamber behind the fireback. It must be cleaned with a vacuum cleaner yearly with thin vacuum brush through a hidden access plate in the top of the stove accessed through the flue pipe opening. Its a cast iron plate under the internal damper. Fine ash will fill in the hidden chamber preventing the primitive second stage combustion system from working. Just as important, lack of flue gas flow behind the fireback creates a temperature differential between the front of the fireback and the rear of it, causing the fireback to warp and crack. The two piece firebacks are less prone to this but it still can happen but less expensive to repair.

The last issue is "backpuffing". The Defiant is a very high output stove designed to heat large spaces like a poorly insulated "barn" of a house. They throw off lots of heat. When they are used in a smaller better insulated space they really do not like to run at low output and they do not like to idle. Standard practice is for people to run them during the evening, then load them up with wood and crank the damper down. The problem is the stove has a hot bed of coals and will convert the fresh wood to gases but the air damper will be near closed preventing oxygen from fully burning the wood. The hot unburnt gases will fill up the chimney until they find a source of oxygen from the top of the chimney and they will ignite causing a small explosion in the stack and the stove. The net result is puff or huff from the stove with the thermostatic air damper snapping open and closed. It can and will lift the top cooking plate. Many Defiant owners leave a cast iron water pot on top of the cooking plate to weigh it down.

The solution to back puffing, is if you need to slow down the amount of heat, you need to do it slowly reducing the amount of wood as the evening goes on and avoid loading it up before going to bed unless you leave the air damper alone or slightly increase its opening. It will create a burst of heat but which many do not want, but if the air damper is closed down to reduce the heat with a fresh load of wood, the stove will backpuff on occasion. It may not happen all the time, in many cases, windy conditions cause turbulence in the stack and that seems to make it worse.

BTW, Defiants can be creosote makers if run in primary air mode with green wood. They are also not much more efficient than a box stove if run in primary mode. Ideally get it started in primary mode, then once up to temperature, flip the damper down and run in secondary mode.

 

[Tpaull]

Time to get yourself a copy of the manual.

Is it a two-piece fireback or one piece?.

Very key to good operation is proper size chimney flue. These need a 8" flue pipe, trying to reduce it to 6" or connecting it to inadequate chimney is asking for problems. Preferably an interior chimney with two stories of height exiting near the ridge pole. These need good draft to run right assuming the internals are not plugged.

The key to the Defiant is a hidden chamber behind the fireback. It must be cleaned with a vacuum cleaner yearly with thin vacuum brush through a hidden access plate in the top of the stove accessed through the flue pipe opening. Its a cast iron plate under the internal damper. Fine ash will fill in the hidden chamber preventing the primitive second stage combustion system from working. Just as important, lack of flue gas flow behind the fireback creates a temperature differential between the front of the fireback and the rear of it, causing the fireback to warp and crack. The two piece firebacks are less prone to this but it still can happen but less expensive to repair.

The last issue is "backpuffing". The Defiant is a very high output stove designed to heat large spaces like a poorly insulated "barn" of a house. They throw off lots of heat. When they are used in a smaller better insulated space they really do not like to run at low output and they do not like to idle. Standard practice is for people to run them during the evening, then load them up with wood and crank the damper down. The problem is the stove has a hot bed of coals and will convert the fresh wood to gases but the air damper will be near closed preventing oxygen from fully burning the wood. The hot unburnt gases will fill up the chimney until they find a source of oxygen from the top of the chimney and they will ignite causing a small explosion in the stack and the stove. The net result is puff or huff from the stove with the thermostatic air damper snapping open and closed. It can and will lift the top cooking plate. Many Defiant owners leave a cast iron water pot on top of the cooking plate to weigh it down.

The solution to back puffing, is if you need to slow down the amount of heat, you need to do it slowly reducing the amount of wood as the evening goes on and avoid loading it up before going to bed unless you leave the air damper alone or slightly increase its opening. It will create a burst of heat but which many do not want, but if the air damper is closed down to reduce the heat with a fresh load of wood, the stove will backpuff on occasion. It may not happen all the time, in many cases, windy conditions cause turbulence in the stack and that seems to make it worse.

BTW, Defiants can be creosote makers if run in primary air mode with green wood. They are also not much more efficient than a box stove if run in primary mode. Ideally get it started in primary mode, then once up to temperature, flip the damper down and run in secondary mode.

I haven’t but it home yet, it’s still in my neighbors garage. I’ve got a masonary chimney about 20-25 feet tall. I would have to reduce down to 6 inch just to get into the chimney opening in the house, but I can run 8 inch from the stove to the inlet of the chimney. I’m not sure if it’s a one ir two piece fireback, I will have to see. Going to get it home, give it a good cleaning and inspection and go from there 🤷🏼‍♂️. I’m heating about 2500 square feet, it’s a split level house and the stove is in the bottom level which means the heat has to travel up two levels to get to the bed rooms so I don’t think it will ever be running at idle. I’m just hoping it will be comparable to the jotul I currently have. In reality im probably only going to use this stove for 1-2 seasons until I’ve got enough money saved up for a new one….unless of course I end up liking it too much which is always a possibility.

 

[peakbagger]

IMHO, find a copy of the rebuild manual, take it apart and reseal all the joints. That necked down connector will be a problem but a good draft may overcome it. For the price, it is probably worth trying and if in doubt if there are no cracks in it you should be able to resell it for more.

 

[Tpaull]

IMHO, find a copy of the rebuild manual, take it apart and reseal all the joints. That necked down connector will be a problem but a good draft may overcome it. For the price, it is probably worth trying and if in doubt if there are no cracks in it you should be able to resell it for more.

I was going to give it a good once over, seal it all off and smoke test it to check for leaks. Probably throw a coat of paint on it and run a couple fires in it outside before putting it in the house

 

[peakbagger]

Good idea about running it outdoors after you have painted it. Lots of surface area to smoke off. You really can not get a secondary burn going with temp stack so the right end with the secondary chamber will smoke once indoors.

 

[claudebo04444]

I just paid $500 for mine because I really wanted a split back, turns out the lower back has couple cracks so going to replace that also ($130) . Am rebuilding it got it all apart and just finished cleaning and prepping. This will go into my new shop.
This is my second one I left the old one at old house, ran that one for 30 years. Love these stoves.
I will run an 8" pipe to the 6" chimney thimble (into an 8" clay liner). Thanks for the heads up on pipe size was going to try the 6" it came with.