Older VC Defiant Owners I need advise

[kwikrp]

I have an older Defiant late 70's early 80's. My problem is with the horizontal burn. I am able to get the griddle temp to 500-600 degrees and I establish a good bed of coals. I would then open the secondary air port and close the damper as instructed in the manual. BUT my temp drops to around 400. Is this to much of a temp drop? Please let me know your experiences or any tips. Thanks

 

[schortie]

I have a much newer version of your stove, but I do experience a significant heat dip on the stove top "thermometer" after I close the damper - this is after I pack the stove full on reload. After a bit, the temps rise back to 600+. Does your temp. rise after a while, or does it stay at 400?

 

[Brian VT]

I'm not familiar with that stove but I suspect that when you move the exhaust to the secondary you're diverting a lot of the heat away from where your thermometer is.
That's how my Resolute funtions.

 

[fraxinus]

Hi Kwikrp,
If your Defiant is one of the original pre-catalytic models, chances are you need to clean out the fine ash which has accumulated between the fire back and the rear casting - this can block the air very easily and if the ash has really filled this space, it can cause the fireback to overheat and crack. The method for cleaning this space has come up a few times in the past year or so, so I'll be brief. With the stove pipe removed and the damper out of the way, look straight down. You'll see a casting that can be removed to gain access. It's far easier, however, to run a vacuum hose down into the space on the left hand side.
I'm not sure what you mean by opening the secondary air port. If you're referring to the hole with a cast iron cover near the side loading door, this should remain open all the time. The flap type thermostat on the stove back is used to adjust the amount of air coming in and thus the heat output.
It's normal for there to be a short period when the temperature drops when you first close the damper, but it should quickly come back up.

 

[kwikrp]

I have cleaned out the fire back as well as resealed the joints for the primary(flap door) passage way as well as the secondary (cast iron cover near side loading door). the temp just hangs at 400.

 

[Valhalla]

I have cleaned out the fire back as well as resealed the joints for the primary(flap door) passage way as well as the secondary (cast iron cover near side loading door). the temp just hangs at 400.

Kwikrp,

Just some basic brain storming questions.

When does the griddle temperature eventually and finally climb? Then to what temp after the wood supply is exhausted? 600F sounds fine.

Is your fixed round air port fully open and always uncovered ? This is very important.

Does the thermostatically controlled flap fully function? If I remember it was at the left for lower temp - to the right for higher temps. I kept mine about 1 o'clock. This position is really a matter of how the chain was adjusted.

The flue and it's condition - how is the draft?

When it is in horizontal burn, as I remember it being called "Horizontal Combustion," can you hear the strong air flow, called by some a rumble ?

One last but tough question for now. How about your seasoned wood? Tell us the type, how and how long was it seasoned?

I owned and loved an original Defiant from 1980 for 14 years. Hope that we can help.

Oops, got to go for now as the wife says the turkey is ready!

Be back.

 

[kwikrp]

The griddle temp drops to 400 maybe within 30 minutes of the switch.
I have usually have it(round air port on side) closed during vertical combustion and the temp climbs very well, I then open it when I switch to Horizontal. I have tried leaving it open all the time, but it the temp climbs faster and higher in vertical.
The thermostatic control appears to be working have not seen it close much on its own, ( any way to test or calibrate it has its own heatshield) but if I move the lever to the left it opens the port more and lets more air in and the right closes the air port.
the flue is 10 X10 clay of an interior mason chimeny about 35 foot tall with only 5 foot exterior. The draft seems great some times when you are closing the door the flames roar and even some ash gets stirred up. When I switch I dont hear a rumble more like ticks or tings
The wood is seasoned hardwood with a moisture level around 15 % tested with a moisture meter.

 

[fraxinus]

With wood as dry as you have, your problem should not be happening. If you're sure you have cleaned out the space behind the fireback - between the fireback and the back casting, I'm really at a loss for an explanation. The reason I keep suggesting the ash issue is this: when you switch to horizontal mode, the main source of air comes through the holes located toward the bottom of the fireback. If these are clogged, the fire will be choked out when you close the damper. If you reopen the damper and open the side loading door after the temperature has fallen, what do you find? If the previously blazing fire has become smokey and the wood is only charred rather than burning, it's a sure sign that the oxygen has been cut off. Another thing to check: when you've switched to the horizontal burn mode by closing the damper, put your hand by the opening controlled by the thermostat flap. You should definitely be able to feel (and hear as another poster said) air rushing into this opening. If you don't feel/hear this, it's another indication of clogging behind the fireback. The only other thing I can think of is that you may have inadvertently sealed something with furnace cement that should have remained open.

 

[Valhalla]

Kwikrp,

The round air port should always be left open, at least from my memory. This allows for minimal combustion air even when the thermostatic flap is fully closed. My suggestion is to always keep it open and burn at least a few tests.

The 400F griddle temp could be caused by the temporary insulating effect of almost 20 inches vertical of room temperature/cold wood added in the firebox. However you should gain horizontal combustion, not loose it over a bed of hot coals and burning splits! Air flow should be by both supply sources until the thermostatic coil stabilizes and almost closes the flap. I always remember the flap slightly bouncing off the square port when my temps were up and cruising in horizontal combustion. The characteristic Vermont Castings air flow is always reassuring.

Clearly, air flow and supply continues to be suspect. Is there a chance to put compressed air or at least vacuum cleaner air output into the two ports and see/feel/hear its flow into the firebox? On a cold and clean stove of course! Watch for flying ash first.

My suggestions for now. Consider them at least. Good luck.

 

[doug60]

I ran that stove at 400 as a norm.
No need to bring it up to 600 before horizontal burn.
I also always left the small round hole open.

Come spring ,take the stove outside if you can. use a leave blower to blow out the fine ash .
Force feed the intake.

Thats a great stove, Mine never missed a beat. Uses wood but very predicable,& nice to look at.

http://picasaweb.google.com/lh/photo/6RQTTbx1ZbkSuaBy_aStGA?authkey=jgqtoJB0kNU&feat=directlink

 

[summit]

I have an older Defiant late 70's early 80's. My problem is with the horizontal burn. I am able to get the griddle temp to 500-600 degrees and I establish a good bed of coals. I would then open the secondary air port and close the damper as instructed in the manual. BUT my temp drops to around 400. Is this to much of a temp drop? Please let me know your experiences or any tips. Thanks

This is normal for almost any stove when you turn it down for a prolonged burn, more so w/ the older vc stoves as all the flame goes daown and away from the stove top when you close the damper.