What Am I Doing Wrong? Too Much Coal Being Used

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stoker-man
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Post Thu. Feb. 21, 2008 1:17 pm

It might be possible to have a positive draft if your air is set too high and the chimney is too small, but it would be at both sides. The draft over the fire is the most important measurement; taken at the door.

Your fire must be stoking and the chimney warm when you do these tests.

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CoalHeat
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Post Thu. Feb. 21, 2008 10:35 pm

I'm not familiar with the meter you are using, but on my Dwyer I'm actually using the portion of the scale which reads in positive increments for the reading. It's interpreted in negative inches of water column. The negative scale is too short to use. The draft reading will increase if you hold the baro's flap closed, will decrease if you hold it open.
MAMOMETER 11-18-07.JPG
Scale reads positive but reading is actually negative pressure.

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e.alleg
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Post Thu. Feb. 21, 2008 11:58 pm

I think he's just reading the scale wrong, if the chimney had positive pressure then I think he'd be complaining of a smell and a massive headache.

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stoker-man
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Post Fri. Feb. 22, 2008 5:45 am

He's using the Bacarac draft meter. The scale is exactly the same as Wood n' Coal's meter, except, the positive side of the scale is on the left.

I don't understand why there is such an emphasis on the positive side of the Dwyer scale when stoves require negative drafts.


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coaledsweat
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Post Fri. Feb. 22, 2008 7:41 am

stoker-man wrote:I don't understand why there is such an emphasis on the positive side of the Dwyer scale when stoves require negative drafts.
There are two hoses on the Dwyer, changing them reverses your reading from positive to negative.

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stoker-man
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Post Fri. Feb. 22, 2008 7:46 am

On the scale picture, it appears that there is a negaitve sign on the left side.

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CoalHeat
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Post Fri. Feb. 22, 2008 7:50 am

stoker-man wrote:He's using the Bacarac draft meter. The scale is exactly the same as Wood n' Coal's meter, except, the positive side of the scale is on the left.

I don't understand why there is such an emphasis on the positive side of the Dwyer scale when stoves require negative drafts.
Only because the Dwyer meter is intended to be connected in a different application, for example on a forced air system to monitor the air flow through a filter. The high side tube is connected to a point before the filter, the low side after. If the filter is after the blower it will read positive pressure. As the filter becomes clogged the reading on the meter will begin to climb.

Since the negative side of the scale is so short we just use the positive side, in effect using the gauge backwards, since it's not positive pressure, but negative pressure (vacuum). The same would be true in a forced air system with the blower after the filter, since it would be all negative pressure.

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