Barometric Pressure and Draft

Here, just back up to check the stove, my barometric pressure here is 1027.5 MB , about 30.3 inches. My draft , with a fire, is only barely .101 >> I know coal has lower stack temps than wood, and when I lived in VT and it was very cold ( clear , and high pressure) it was hard to start the wood stove. My Coal stove does have 3 90's and 4 ft 6 inches above the roof. The fire is very lazy, and its up to about 375, but not all the coal will light, and heat output is down..I was not expecting this to be an issue to this extent. I had .30 draft the other day after it had been stormy, fire was hot and doing well. Anyone else getting slow fires tonight, today?

At .3 don't let the car get too close to draft regulator or will get sucked into chimney. I run .03 one tenth of what you are talking about. I suspect the grates not shaken and sliced if need be. If you don't see bright orange above the grates you are not done tending the stove. That will easily cut the air through the coal bed and end up with a lazy or no fire. With .3 or even .1 draft the stove should look like a foundry.

ddahlgren wrote:With .3 or even .1 draft the stove should look like a foundry.

I'm thinking the OP made a math error on a 10 factor scale in his reading of the manometer.

lsayre wrote:

ddahlgren wrote:With .3 or even .1 draft the stove should look like a foundry.

I'm thinking the OP made a math error on a 10 factor scale in his reading of the manometer.

.101 and the stove is not putting out much heat, there must be a missing zero to the right of the decimal point.

I'm also curious as to what brand mano has a scale that can give a reading of .101 ?

Can an orange glow be seen throughout the ash pan after shaking ashes ?

Paul

Formulabruce wrote:Here, just back up to check the stove, my barometric pressure here is 1027.5 MB , about 30.3 inches. My draft , with a fire, is only barely .101

My personal opinion is that outdoor barometric pressure has no bearing on chimney draft. The reason is because house pressure always tries to equalize with outdoor pressure, and it does quite easily by opening a door or just thru natural gaps and cracks in the construction. Temperature difference between outdoors and indoors is the biggest player for causing natural stack effect in the house and would cause some of the variations in mano readings you see. Speaking of which, I assume you meant .01 and .03 as opposed to .101 and .30 respectively in your first post.

Formulabruce wrote:The fire is very lazy, and its up to about 375, but not all the coal will light, and heat output is down..

I would suspect that you have some ash bounding the coal bed in particular places. Try poking up the bottom to free it up and shake it out.

Sunny Boy wrote:...8<... .101 and the stove is not putting out much heat, there must be a missing zero to the right of the decimal point.

I'm also curious as to what brand mano has a scale that can give a reading of .101 ? ...>8...

Paul

Two are available:

• It's cutting it close to call 0.101 but look at a Dwyer Model 460 Air Meter
  • "pressure ranges from .005-.09 and .05 -1.0 in w.c."
• Series 2000 Magnehelic® Differential Pressure Gage
  • "2000-00 Differential pressure gage, range 0-0.25" w.c., minor divisions .005, calibrated for vertical scale position."

AS Tim the Tool Man Taylor would say:

More Pressure is good, VROOOMMMM!!!!!! Of course when Jill's
dishwasher exploded through the island in the kitchen he was
not expecting that.

VigIIPeaBurner wrote:

Sunny Boy wrote:...8<... .101 and the stove is not putting out much heat, there must be a missing zero to the right of the decimal point.

I'm also curious as to what brand mano has a scale that can give a reading of .101 ? ...>8...

Paul

Two are available:

• It's cutting it close to call 0.101 but look at a Dwyer Model 460 Air Meter
  • "pressure ranges from .005-.09 and .05 -1.0 in w.c."
• Series 2000 Magnehelic® Differential Pressure Gage
  • "2000-00 Differential pressure gage, range 0-0.25" w.c., minor divisions .005, calibrated for vertical scale position."

I can see the 2000-00 model has a scale that reads to three places, http://www.ebay.com/itm/Dwyer-Magnehelic-Differen ... 338ec70958

I have a 460 and while it will read that low, at such low readings, the slight amounts of air that get pulled through it develop static electricity, which makes the ball stick and throws the readings off by as much as 0.10.

Paul

Sunny Boy wrote:I can see the 2000-00 model has a scale that reads to three places, http://www.ebay.com/itm/Dwyer-Magnehelic-Differen ... 338ec70958

I have a 460 and while it will read that low, at such low readings, the slight amounts of air that get pulled through it develop static electricity, which makes the ball stick and throws the readings off by as much as 0.10.

Paul

On the 460, I agree which is what I meant it would be calling is close. It takes some occasional maintenance to clean the tube (remember the pipe cleaners that came with it?) and replace the ball.

I find my stove requires different settings for different OAT & density altitude (ambient pressure).

The colder and drier it is the "Better" the stove runs.

scalabro wrote:I find my stove requires different settings for different OAT & density altitude (ambient pressure).

The colder and drier it is the "Better" the stove runs.

I will agree with ^^^^^^^^^^^^^^^ what he said. B4 our wood stove days we had a Duo-Therm kerosene heater for 21 yrs. that vented thru a 6" pipe with an baro in it,weather conditions definitely made a big difference on the stack draft or pressure which ever you feel like calling it.

I did have the decimal off by one, was listening to my friend read it. ( was .01)
My wife turned on the dryer, same floor, and I didnt realize it, that lowered my draft, even with window open a crack near the stove
I live in a river valley ( higher pressure) and will keep a record of baro pressure. I know it can equalize in the house, but higer pressure keeps smoke down outside and does affect hot air rising. Since my stove has 3 90's in the flue system, I had some concerns... IT's back up to temp and running well now.
thanks for the comments !!