Taming the wild Quadrafire 2100, part 2A

[precaud]

Taming the wild Quadrafire 2100, part 2A

Part 1 described the issues I encountered with this stove, and highlighted some areas where changes might/could be made. So let's do some tweaking and see what happens. You might want to refer to part one for photos 1 thru 8, so here are the links:
https://www.hearth.com/talk/threads/5429/
https://www.hearth.com/talk/threads/5430/

First on the agenda is to slow down the burn rate. Experienced woodburners know that, to stimulate a fire, you give it more so-called "underfire air," which meets the wood at the level of the coals bed or below. So in the case of a hard-to-control stove, the first thing to look into is restricting any underfire air sources. The Quad 2100 has two; one in front and one in back. The one in front is larger and has the biggest influence. Many modern stoves have an underfire air source at the front of the stove like this (see photo 9). It's a part of the primary air system, which can't be closed off, so a strong stream of air comes out of this thing at all times, right to the base of the fire, exciting it to burn hotter and hotter. This sets the minimum burn rate of the stove very high. It's a simple matter to lessen the stream by blocking part of the hole. I like to use little clips that I cut from strips of sheet metal, bend into shape with needle-nose pliers, and then file down to exact dimensions (see photo 10.) Photo 11 shows the clip in place, reducing the hole diameter by a little less than half.

The other underfire air source is at the back of the stove, fed by the startup air system. It plays it's role mostly toward the end of the burn, making sure the logs at the back of the firebox aren't starved for air. This too needs to be trimmed back a little to tame the inferno. A similar clip is placed into the hole at the bottom rear of the stove (see photo 8.)

Next I removed the stop screw in the primary air feed (see photo 6), which allows it to be closed down more, even all the way shut if desired.

With those three mods we now can control the fire. Next let's see if we can clean up the glass. Remember we discovered that this stove's design robs some of the air destined for the airwash and feeds it directly into the exhaust stream (see photo 5) ? We want to give some of this air back to the glass to keep it cleaner. I made and installed clips to reduce the middle 12 of the 14 holes (see photo 12.) The two outermost holes were blocked completely with stove cement to give even more air to the airwash where the glass was sooting up the worse.

Next on the list is to discover why the stove had a right-to-left "swirl" burn pattern, which also causes the dirtier glass on the left side. In prior work with stoves, I learned that symmetry in construction, air feeds and exhaust is critical. So I looked for firebox leaks and construction defects of any kind.

The baffle above the secondary tubes is cut to fit loosely enough to allow for expansion and easy removal. That is one possible leak source. I measured the dimensions of the exhaust chamber opening. Well well, it was just under 1/8" taller on the left side than the right.That may not sound like much, but it gives about 6% larger area to that opening on the left side, easily enough to cause the exhaust to pull stronger on the left. So I cut a strip of 3/32" thick sheet metal, half the stove internal width, and placed it at the front-left edge of the secondary baffle. Then I cut a piece of 1/4" kaowool and covered the entire top of the secondary baffle. This will deal with any leaks around the baffle.

(continued in Part 2B, so photos can be included with the text)