Barometric Damper : Draft Pressure Setting

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Lightning
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Post Tue. Nov. 05, 2013 6:22 pm

I recently moved the weight out on my baro door to make it more sensitive to draft. Under normal conditions (no high winds or extreme cold) my baro won't allow my draft to exceed a -.035"wc. I like to keep my draft pressure between a -.02 and a -.035.. I took pictures of it at various draft pressures. The pictures are increments of -.01 starting at -.01 and the last pic is at -.05.. I used a MPD and draft inducer to manipulate my draft pressures.. I was wondering if others that use the Field Controls RC see the baro door open at the same angle with same amount of draft as in the pictures.

Heres at -.01"wc.. The door is nearly completely shut but not up against the stop on the baro housing.
baor01.jpg
The next pic is at -.02"wc
baro02.jpg
Here is -.03"wc
baro03.jpg
Here is -.04"wc
baro04.jpg
Here is -.05"wc
baro05.jpg


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mozz
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Post Tue. Nov. 05, 2013 6:51 pm

Is it level? Looks a bit off. Also, if you take it off and clean all the buildup on the weight and flapper, it will move easier. Scrubbed mine with a small wire brush this year and it swings like it was new. My 5" baro pegs wide open all the time, draft is too much with chimney going through the center of the house when it is cold out.

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Post Tue. Nov. 05, 2013 6:52 pm

I think the observations you make are great, but in this case I don't think you will get an answer because it first requires the calibration of barely opening at .01 and running up to .05 which most will not have either the manual pipe damper or adequate chimney to achieve.

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Lightning
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Post Tue. Nov. 05, 2013 7:13 pm

mozz wrote:Is it level? Looks a bit off. Also, if you take it off and clean all the buildup on the weight and flapper, it will move easier. Scrubbed mine with a small wire brush this year and it swings like it was new. My 5" baro pegs wide open all the time, draft is too much with chimney going through the center of the house when it is cold out.
Oh yeah, It's perfectly level both ways. I used an oblique camera angle to show the door position the best. I keep it clean too, I brush fly ash off it with a tooth brush about every two weeks lol. :)

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Lightning
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Post Tue. Nov. 05, 2013 7:20 pm

franco b wrote:I think the observations you make are great, but in this case I don't think you will get an answer because it first requires the calibration of barely opening at .01 and running up to .05 which most will not have either the manual pipe damper or adequate chimney to achieve.
Thanks Franco :D I was hoping that maybe someone would chime in with what their door position is at say a -.03 or -.04 as compared to my door's position. Just curious to see if people run theirs this sensitive or if they need more negative draft to achieve the same door position.

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Post Tue. Nov. 05, 2013 7:26 pm

I can't contribute here because I have the Type M damper. Mine is just beginning to crack open at 0.04" of WC.

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Lightning
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Post Tue. Nov. 05, 2013 8:05 pm

lsayre wrote:I can't contribute here because I have the Type M damper. Mine is just beginning to crack open at 0.04" of WC.
I've considered trying a type M. So if it's just beginning to open at -.04, what pressure is it at when it's at about a 60 degree angle?

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Post Tue. Nov. 05, 2013 8:58 pm

I have looked into the Fields site. I wonder if the weight should be on the left side, so it will behave differently. I would call them, as their online resources do not clarify.


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Lightning
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Post Tue. Nov. 05, 2013 9:09 pm

2001Sierra wrote:I have looked into the Fields site. I wonder if the weight should be on the left side, so it will behave differently. I would call them, as their online resources do not clarify.
One side is for a horizontal pipe, the other side is for a vertical pipe. Why it would make a difference I don't know. I found that the side it's on currently, reacts more sensitively than the same position on the other side. The path for the weight seems to be inclined slightly more on this side also. I have a diagonal pipe so I guess it's just "pick one" hahaha.

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Post Tue. Nov. 05, 2013 11:07 pm

I had my Type M on the oil boiler set to .02 .. so, it was open constantly - just at varying levels depending on the wind gusts.

The oil burner is very abusive to it though. Each time the burner kicks on, the thing slams shut with force. So much force that I found it stuck shut more than once. Pisses me off - that damn thing was expensive! Should've left the cheap ass one on there .... :roll:

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Post Tue. Nov. 05, 2013 11:29 pm

i guess don't understand how you are setting up your testing at different pressures with the different openings or what you are trying to determine. :?

my baro position and the mano readings are the opposite of yours. I do not have a draft inducer or a manual damper. my manometer is connected prior to the baro. after the stove has reached firing temp (as opposed to idle temp) if I intentionally close my baro to the position you have in your first pic my draft will read roughly .06 depending on how cold it is outside. if I force open it up to the position you have in the last pic the draft will drop to about .02.

if I leave the baro to work on its own, it will maintain a .04 reading on the manometer while being open varying amounts from all the way closed to just about wide open, depending on the wind.

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Post Wed. Nov. 06, 2013 6:08 am

Lightning wrote:
lsayre wrote:I can't contribute here because I have the Type M damper. Mine is just beginning to crack open at 0.04" of WC.
I've considered trying a type M. So if it's just beginning to open at -.04, what pressure is it at when it's at about a 60 degree angle?
By 0.05" it is about wide open. It is incredibly sensitive.

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Lightning
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Post Wed. Nov. 06, 2013 6:46 am

Thanks Larry, That's good information. So the type M keeps your draft in a narrow range which is what you want. The RC keeps it in a slightly wider range.

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Post Wed. Nov. 06, 2013 6:55 am

Lightning wrote:
One side is for a horizontal pipe, the other side is for a vertical pipe. Why it would make a difference I don't know. I found that the side it's on currently, reacts more sensitively than the same position on the other side. The path for the weight seems to be inclined slightly more on this side also. I have a diagonal pipe so I guess it's just "pick one" hahaha.
Haha, I was looking at mine as well curious which side to use because mine is set up at a 90* called a bull nose and I came to the same conclusion...whichever side you need to get the results you want! HA!

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Lightning
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Post Wed. Nov. 06, 2013 7:54 am

titleist1 wrote:i guess don't understand how you are setting up your testing at different pressures with the different openings or what you are trying to determine.

my baro position and the mano readings are the opposite of yours. I do not have a draft inducer or a manual damper. my manometer is connected prior to the baro. after the stove has reached firing temp (as opposed to idle temp) if I intentionally close my baro to the position you have in your first pic my draft will read roughly .06 depending on how cold it is outside. if I force open it up to the position you have in the last pic the draft will drop to about .02.

if I leave the baro to work on its own, it will maintain a .04 reading on the manometer while being open varying amounts from all the way closed to just about wide open, depending on the wind.
I realize the mention of using the draft inducer and manual damper to manipulate the draft pressure may have confused some people :( . I was trying to get a reference for where others set their weight on their baro door during "normal" burning conditions. So the pictures at -.04 and -.05 don't really apply since I used the inducer to exceed the drafting strength of the chimney. It seems that with my set up, my baro will keep the draft inside a particular range, for example between a -.02 (where it starts to open) and a -.04 (where its approaching a 45 degree angle) which is a .02"wc range.

Larry says his stays in a .01 range (-.04 starts to open to a -.05 where its almost wide open) a narrower range for a more consistent draft pressure. I likey :)

Its amazing how sensitive a hand fed is to draft pressure (mine seems to be). My furnace ran between 260-263 degrees all night long. This morning I saw my baro was holding draft at a -.02"wc with the baro door open at about a 60 degree angle. I decided this was a hair weak (I have a fiddling issue :lol: ) SO, I moved the baro weight toward the door about a 1/16 of an inch so it would hold it at a -.025"wc.. This small adjustment in draft caused my furnace temp (measured over the load door) to increase 12 degrees (from 261 to 273 degrees) over the period of an hour.


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