Older VC Defiant Air supply adjustments

[kwikrp]

I was wondering if someone could describe the way they adjust their air supply using the primsry and secondary both in Verticle mode and then in horizontal burn ?
I am learning this stove have had some issues to overcome. I am able to get the griddle temp up to 500 with the secondary( small round cover next to load door ) open and the primary ( adjustable air door on lower left back ) open half way in verticle burn, but how do I know if I am closing it to much or to quick ? When the temp drops? how long do you wait between adjustments?and how open do you usually have your air adjustment to acheive max heat with max burn time? the manual says to close the damper to go into horizontal burn the stove should be minimum of 500. Do you add more air when you close the damper or leave it as is or close it some if so how much please describe the more detail the better.

 

[kwikrp]

forgot sorry....What do you do when you reload, leave the air the same, add more?

 

[fraxinus]

If you're writing about the original pre-catalytic Defiants from the 1970's: The round opening with the cast iron cover located below/behind the side loading door should remain open all the time. When the damper is open, the stove is in a vertical burn mode. This is the way the stove operates when first starting a fire or when the two front doors are open for fire viewing. When the damper is closed, the stove shifts to horizontal burn mode. Now the intensity of the fire and the temperature can be regulated with the thermostat at the rear of the stove. The thermostat uses a chain connected to a bimetallic coil. It closes the metal flap when the stove grows hotter and opens it as the stove cools - it's adjusting all the time. There are too many variables - species of wood, how dry it is, for examples - to make a hard and fast rule about how long the stove remains in vertical burn before shifting to horizontal. A thermometer can be used, but generally I go by the heat radiating from the stove. Once I can definitely feel it, I close the damper.

 

[kwikrp]

what are you suppose to see when you switch from vertical to horizontal ? Longer hotter burns?

 

[fraxinus]

The horizontal burn mode is more efficient in that it captures more heat from a given quantity of wood by redirecting gasses over the hot coals before they go up the chimney. This is probably a very unsophisticated secondary burn system compared to more modern EPA stoves, but it's great virtues are simplicity and ease in regulating the heat output. Two things to be careful of with this stove: Don't run it in a low air, shut down mode for lengthy periods. This results in a lot of creosote and was usually a problem for people who bought this stove for too small a space and ran it with the thermostat damper closed because it produced too much heat for their needs. Second, if you find it difficult to maintain a fire in the horizontal mode, chances are ash has built up between the fireback and the rear casting. Ash should be removed from this area annually. You can downlload a complete manual for this stove at Vermont Castings website.

 

[kwikrp]

in horizontal mode do you add more air when you close the damper ? I get the stove griddle temp to 535+ and then switch, with a good bed of coals, and the temp begins to creep down and the heat output begins to diminish. Should I open the primary before making the switch.

 

[fraxinus]

When you close the damper, the temperature decreases for a short time just as it does when you add wood to the firebox. Introducing more air at this point by using the thermostat lever may help the temperature come back up more quickly, but a lot again depends on the dryness, size and species of wood. If when you close the damper the temperature decreases and does not come back up after 15 or 20 minutes or at all you probably have either clogged secondary air tubes because of ash behind the fireback (most likely cause) or the wood is not very dry. Remember too, that you leave the opening by the side loading door open all the time; there's no adjustment necessary. The thermostat adjusts the amount of air/oxygen entering the stove.