draft measurement

Just used my manometer to measure the draft on my stove. Idle fire, calm day, 45 degrees F I show about 2 mm or .07" of WC. I expected to have high draft just from the feel of the draft when I relined my chimney with 6" stainless flex. Should I consider adjusting my baro to reduce the draft to closer to .04 or just leave it alone? Stove seems to burn properly, but I don't understand the implications of having too much draft (not that .07 is too much...or maybe it is...I dunno)

Your thoughts?

Thanks

av8r wrote:Should I consider adjusting my baro to reduce the draft to closer to .04 or just leave it alone? Stove seems to burn properly, but I don't understand the implications of having too much draft (not that .07 is too much...or maybe it is...I dunno)

.07 is high, most hand fireds will cap the draft at .06, stokers tend to be lower. I don't know what your unit is, but I would tone it down to at least .06, maybe even .05. You are giving some heat away with the higher draft. The manufacturer should be able to give you the minimum and maximum draft settings your unit requires.

More heat up the chimney, less heat in the house if your draft is too high.
Most of the stoker stoves should be around .02-.04. Idle it should be set for lowest draft setting. With your baro set accurately, it should maintain pretty close to you setting. .07 does seem a bit high.
Check it with a good fire burning, the draft will increase with the more heat, so you draft may go up even more.

As I recall Leisure Line recommends .04.

I asked this question of Jerry (Leisure Line) quite a while ago and he told me about .02 at idle and I could go to .05 at high fire. He also stated that with a high draft (he didn't say how high) there is a possibility of a hopper fire. I guess that if there is a high draft the stove sucks a lot of air through the hopper and can cause the coal to burn back.

By: Leisure Line On: Wed Aug 01, 2007 3:01 pm

Hi Gambler,
We always recommend a -.02 at low, to .05 at high. With everything taken into consideration, setting the weight on 2/3 will be a real good starting point. Make sure the stove and chimney are at operating temp. for a few hrs. This is very important for a proper setting.
Good luck,
Jerry

gambler wrote:I asked this question of Jerry (Leisure Line) quite a while ago and he told me about .02 at idle and I could go to .05 at high fire. He also stated that with a high draft (he didn't say how high) there is a possibility of a hopper fire. I guess that if there is a high draft the stove sucks a lot of air through the hopper and can cause the coal to burn back.

Thanks, Rick.

Now the next question. I can't really measure my draft in the pipe before the baro because my T and baro are mounted right on the collar on the stove so I'm going to tap a hole in the very bottom edge of the stove on the side closest to the exhaust hole and measure from there. I'm assuming there won't be much difference in the measurement?

Thanks much.

I'm assuming there won't be much difference in the measurement?

From my understanding that is a completely different draft (over fire draft) than the flue draft and should be significantly lower. Maybe some of the experts will chime in.

Chimney draft needs to be checked in the stovepipe prior to the Baro if there is one. If you measure the draft before the stoves outlet it will be overfire draft and that can vary considerably from the chimney, usaully much lower. Chimney draft is what the baro is set to, nothing else.

coaledsweat wrote:Chimney draft needs to be checked in the stovepipe prior to the Baro if there is one. If you measure the draft before the stoves outlet it will be overfire draft and that can vary considerably from the chimney, usaully much lower. Chimney draft is what the baro is set to, nothing else.

OK..so...seeing as I can't really get more than an inch or so from the baro to take the measurement before it, what would you suggest?

Thanks

With the stove warmed up and the stoker running, strive for .03 over the fire and .05 in the pipe. Your manual should have the exact setting, it might be .02 over the fire and .04 in the pipe, or .04 and .06 but these numbers are close. There aren't any separate adjustments for over fire or flue draft, it's best to check them both and make sure you have enough in both spots.

e.alleg wrote:With the stove warmed up and the stoker running, strive for .03 over the fire and .05 in the pipe. Your manual should have the exact setting, it might be .02 over the fire and .04 in the pipe, or .04 and .06 but these numbers are close. There aren't any separate adjustments for over fire or flue draft, it's best to check them both and make sure you have enough in both spots.

I just re-read the manual and I can't find anything about the actual draft number needed. Draft is mentioned, but nothing specific.

Update:

I removed one of the screws that hold the T and baro and used a ball inflation needle (thanks, Matthaus) to measure the draft in the only possible spot that isn't in the stove and as far away from the baro as possible (maybe a few inches from the baro). Idle fire, somewhat breezy night I had about 1 mm of WC or .04" of WC. I then manually stoked the fire up to a full burn and the measurement never changed. I then closed off the combustion air intake with my hand and the measurement bounced a bit but then leveled off to 1mm. I then tried to hold the baro closed using a piece of coat hanger (I can't see my baro as it's inside the firebox behind the stove) and I didn't see any significant movement on the manometer. So...I guess I either can't get an unaffected reading due to my only measurement point being in such close proximity to the baro and/or the baro is working exactly as expected and my initial setting on it is correct.
So...does this sound about right? If the baro is working right and my measurement point is too close to it, should I expect the reading to be whatever the baro is set to? Should I bother trying to drill and tap the stove body and measure there? I can actually get within 2" of the exhaust flange on the inside of the stove with the hole. Are these measurements close enough that I should just find something else to occupy my time?
Thanks

av8r wrote:Should I bother trying to drill and tap the stove body and measure there? I can actually get within 2" of the exhaust flange on the inside of the stove with the hole. Are these measurements close enough that I should just find something else to occupy my time?
Thanks

IMO you should be OK with what you have, I have had good luck just checking the draft in the pipe, and I did a little experiment on the Keystoker in the garage. took screws out from the flange on the furnace all the way to the T on the Baro, not a whole lot of difference in draft gauge reading at each location. Since every pipe configuration will lead to different flow this test in no way reflects your conditions.. but I guess I offer it as a data point.

So bottom line, drill and tap if you are looking to continue the science project, but my feeling is you are good with what you have set up.

Matthaus wrote:

av8r wrote:Should I bother trying to drill and tap the stove body and measure there? I can actually get within 2" of the exhaust flange on the inside of the stove with the hole. Are these measurements close enough that I should just find something else to occupy my time?
Thanks

IMO you should be OK with what you have, I have had good luck just checking the draft in the pipe, and I did a little experiment on the Keystoker in the garage. took screws out from the flange on the furnace all the way to the T on the Baro, not a whole lot of difference in draft gauge reading at each location. Since every pipe configuration will lead to different flow this test in no way reflects your conditions.. but I guess I offer it as a data point.

So bottom line, drill and tap if you are looking to continue the science project, but my feeling is you are good with what you have set up.

Thanks, Matt.

I'm sure I'll be compelled to get the drill out..it's calling my name...