Manometer Reading

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ScottD
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Post by ScottD » Thu. Oct. 30, 2008 11:37 pm

OK, I have my manometer hooked up and am reading my stoves correct numbers.
My question is to me and other newbies;
When I read .04 or -.04, is it primarily where I attach my hose on my manometer? Low or High? It seems the numbers are the same + or - depending where you attach it to the manometer. The reason I mentioned it is because it is mentioned - or + in the same posts and some people don't know what that means. Those in the know, please clarify. People may have the belief that it is a good draft when in actuality it will kill them!
Sorry if I'm the only dope thinking this way.

Scott

 
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Devil505
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Post by Devil505 » Fri. Oct. 31, 2008 5:38 am

ScottD wrote:People may have the belief that it is a good draft when in actuality it will kill them!
Don't understand???? :?

 
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Post by WNY » Fri. Oct. 31, 2008 6:19 am

Yes, depending on HOW you hook up the low or high, that will make it read PLus or MINUS on the scale. Most of us hook it to the POSITIVE SIde (I think high), Larger scale (Not that it matters, since you are measuring such a low number) So, the scale goes to the right (+.03) everyone just has to know that if it goes to Zero (0) or to the opposite of the scale, you have a problem. I believe most people are using the plus or minus interchangeable.

Basically, It doesn't matter which way it reads, just as long as you realize what it means and know what you have vacuum on the stove and it's above the zero mark. :)

 
ScottD
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Post by ScottD » Fri. Oct. 31, 2008 6:35 am

Dave,
That's what I was getting at. Just wanted to clarify it. Thanks

Devil,
The reason I asked was because of it mentioned so many time + and - in the same threads, I don't want someone to read a positive pressure by accident. There are some people who don't have CO detectors. If they are only using a Manometer, I want them to understand it.


 
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Devil505
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Post by Devil505 » Fri. Oct. 31, 2008 6:50 am

ScottD wrote:Devil,
The reason I asked was because of it mentioned so many time + and - in the same threads, I don't want someone to read a positive pressure by accident. There are some people who don't have CO detectors. If they are only using a Manometer, I want them to understand it.
Greg is the real manometer expert here but I think I'm accurate when I say:

1. Assuming you have first established a draft, a manometer reading is displaying the amount of vacuum (sucking) that your chimney is experiencing,( not positive pressure) & thus gases will be sucked INTO your stove, stovepipe & chimney, not be pushed out.

2. You should never operate a stove without a (functioning) CO detector (or 2) installed!

 
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Post by ScottD » Fri. Oct. 31, 2008 7:18 am

Devil,
I agree with 2 CO detectors!
What I was getting at is that a lot of people establish their drafts WITH a manometer. If you are hooking it up wrong, I wouldn't want anyone to see a downdraft falsely and go to bed. It popped into my head last night. Maybe I am over thinking this. Just want everyone to be safe this winter. I am constantly checking it myself.

 
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Post by Devil505 » Fri. Oct. 31, 2008 8:27 am

ScottD wrote:Devil,
I agree with 2 CO detectors!
What I was getting at is that a lot of people establish their drafts WITH a manometer. If you are hooking it up wrong, I wouldn't want anyone to see a downdraft falsely and go to bed. It popped into my head last night. Maybe I am over thinking this. Just want everyone to be safe this winter. I am constantly checking it myself.
When you say "establish their drafts WITH a manometer" I assume you mean MEASURE their draft?
Once your fire is going, your chimney will always be 'drawing" from your stove. A downdraft may weaken your draft, but I can't imagine a scenario that your chimney will create positive pressure & force smoke & CO back into your house???

In any case, having working CO detectors gives you all the protection you need.

 
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Post by LsFarm » Fri. Oct. 31, 2008 1:27 pm

If you have a really tight house, and a minimal drawing chimney, and you turn on several exhaust fans, like two bathroom fans, a kitchen range hood fan and run the clothes dryer,, it is quite concievable to get a reverse draft in a weak chimney.. That's what the CO detectors are all about..

Dev, that is why I classify your chimney as 'borderline dangerous'.. It is only because of your years of experience that you get away with burning a handfeed with only .02-.03"wc..

As for the + / - discussion, this is semantics.. but a draft or draw is always a [-] negative.. but I agree that someone needs to know how the meter is plumbed to know what it is reading..

This is one reason that the 'Loaner Manometer Program' now has mechanical manometers, that read only one way.. less explaining, and simpler to hook up.

Greg L


 
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Post by Devil505 » Fri. Oct. 31, 2008 1:52 pm

LsFarm wrote:If you have a really tight house, and a minimal drawing chimney, and you turn on several exhaust fans, like two bathroom fans, a kitchen range hood fan and run the clothes dryer,, it is quite concievable to get a reverse draft in a weak chimney.. That's what the CO detectors are all about..
Another way to do this is with a whole house fan. (I have done it once or twice in the early spring when I had the coal stove still going & turned on the WHFan) You should tape off the WHFan switch when you have the stove going!

I was referring to a natural scenario that could cause a draw to reverse & just wasn't sure if Scott was getting the concepts correct when he said this:
ScottD wrote:I wouldn't want anyone to see a downdraft falsely and go to bed. It popped into my head last night.

 
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Post by coaledsweat » Fri. Oct. 31, 2008 2:09 pm

Draft reversal would be a rare occurrence in a flue with a solid fuel appliance operating into it. But be warned, it is not uncommon to have a reversal in multiple flue chimneys. The solid fuel one will be expelling exhaust and the gas/oil appliance and the nearby flue could become your makeup air (and bring with it your solid fuel combustion byproducts from the working flue). A good reason for a electric stack damper for said gas/oil appliance, or outside combustion air for the solid fuel unit. The draft reversal can also use a fireplace if the damper is not closed. This trend is more noticeable as the draft gets higher and demand for makeup air goes up.

 
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Post by arcticcatmatt » Fri. Oct. 31, 2008 2:25 pm

Won't your reading vary by day?

My chimney/stove inspector told me to save my money on a manometer. He said it changes daily so whats the point of one? He told me to adjust my barometric damper to that it just barely wobbles a little bit "tink, tink, tink" when the stove is running.

 
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Post by LsFarm » Fri. Oct. 31, 2008 2:39 pm

I'd ask that guy : Just how much draft is 'tink tink tink? The whole idea is is to control too much draft. So how do you know if it's too much??

The draft will change slightly with weather changes, but you have a built in safety device with a manometer. If the chimney becomes partially clogged with ash, your draft will drop.. you will notice this if you have a full time manometer. Without the meter, you will only know if you look or if the CO detector goes off.

I don't believe a manometer is wasted money at all.

We have a 'Loaner Manometer Program' for people who don't want to spend the money,, and only care to set the Baro once.. That's why we created the program.

Greg L.

 
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Post by coaledsweat » Fri. Oct. 31, 2008 5:20 pm

arcticcatmatt wrote:Won't your reading vary by day?

My chimney/stove inspector told me to save my money on a manometer. He said it changes daily so whats the point of one? He told me to adjust my barometric damper to that it just barely wobbles a little bit "tink, tink, tink" when the stove is running.
He is confused, the atmospheric pressure changes day to day. The setpoint of your baro will not as it works off of the differential between the room and the stovepipe. "The point" is to limit the units maximum draft and not waste heat or overfire the unit. Setting it to tink is exactly that, you have no idea what the draft truly is.

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