# manometer



## trettig (Nov 17, 2011)

I need to test my chimney's draft.  It was suggested to purchase a manometer to test draft.  Does anyone know what manometer I should buy.  I am only going to use it a few times.  So an expensive model doesn't seem to make sense.


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## Jackfre (Nov 17, 2011)

Do you know anyone who works for an oil company? Thay have to do draft tests when cleaning/setting up oil burners. Ask around a bit.


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## fossil (Nov 17, 2011)

A manometer is a simple device, basically consisting of a piece of tubing shaped in sort of a J, and a bit of fluid is introduced (of course, they can get a_ lot_ fancier).  It will indicate the difference in gauge pressure between the two legs.  When there is no difference, the fluid level will be the same in both legs.  When there is a pressure difference, the fluid will be displaced...dropping in one leg and rising in the other. (Think sucking very gently on a straw...you can get the fluid to rise just a bit and stay there).  Measuring the distance of the fluid displacement between the two legs of the manometer will quantify the pressure differential.  For small differentials (like a solid fuel-burning appliance flue draft) the fluid is typically water, thus the measurements are expressed in inches of water.  The problems I see in using a manometer to measure your draft are that you will have to drill a hole in your flue to attach it, and obtain an instrument that can withstand high temperatures.  Did whoever is recommending this to you happen to give you any guidance as to just how to go about it?  Rick


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## CaddyUser (Nov 17, 2011)

Check with your local stove/chimney installer.  They might be able to help you out.  Most installers around here don't have that type of equipment; that's why I got into doing those types of things on the side.  I've been doing draft checks and video inspections for a couple years now....

If I was closer, I'd drop by to do it....  Just don't tell my better half though.  She'd love to head to Boston & Cape Cod for the fun of it!!  Then again, so would I


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## Danno77 (Nov 17, 2011)

Let's say you get a reading. What does it mean? Are there appropriate draft readings? I mean will you be better off than if you stick a hand over the chimney and say "yeah, that feels like a good draft"?


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## CaddyUser (Nov 17, 2011)

Generally, draft falls into three categories, excessive negative, normal, and excessive positive.  Excessive negative causes more heat to head up the stack and possible overfiring of the stove, excessive positive causes smoke spillage into the living area.  Normal is relative, and can vary quite a bit, depending on barometric pressure and temperature variance between outdoor and indoor temps.

Any wood burning appliance that has an adjustable draft is going to vary the stack draft, so it's really only those that have on/off drafts, like those on furnaces that are of a concern.  These can lead to the excessive situations as I mentioned.  Open fireplaces are another matter.  Granted, excessive situations can occur with adjustables too, especially when the stove is not matched correctly to the chimney. Too high, and/or too large chimneys can cause 'interesting' problems.

That's why a lot of furnace installs require the use of a barometric damper.  Manual dampers, although used quite a bit, are not permitted in some locations because of the possibilities of excessive situations that are due to the operator.

Most of tests that I do end up doing data collection of both stack temps and differential pressure over a number of hours.  Doing a test for a small amount of time doesn't really show much, unless the appliance is spewing smoke into the living area most of the time, or is turning the stove cherry red.

This is not a complete take on draft and spillage - who thought burning wood was so complicated.....


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## trettig (Nov 17, 2011)

I should have said - my hearthstone equinox is not running hot enough.  The best I can get is 400 degrees out of the stone.  Even with dry pine boards.  I talked to Hearthstone - they recommended using a manometer to measure my draft in my chimney.  HE SAID THE DRAFT SOULD BE - between .05  - .09 - over .10 - is an overdraft and could be sucking heat out of chimney.  Heating season is here and I need to figure this out.  Again as always - thanks for all your suggestions.  
Tom


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## maple1 (Nov 17, 2011)

Here's the one I just got. Ordered it Monday, it showed up yesterday. Haven't had chance to take out of box yet.

http://www.dwyer-direct.com/shop/it...em=25&manufacturer;=&manufacturerItemNumber;=


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## EJL923 (Nov 17, 2011)

You can find cheap manometers, like the one mentioned above.  It is made by a reputable company.  You just have to make sure the scale is correct for your application.  I think the manometer pictured above wouldnt be good for this application.  Its scale is 0-3" water column (in H20).  Whoever told you is correct in the range, he suggested .05-.09, which im sure he meant inH2O.  Jotul recommends 10-20 pascals, which equates to about that.  Measuring this small amount on a 0-3" meter probably would be too small to read.  I know i have overdraft in my chimney, and have thought about doing the same.  The problem is even if i confirm i have overdraft, my options are limited to fix it with an insert.


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## DanCorcoran (Nov 17, 2011)

From Dwyer's website, it appears that a manometer with the precision needed for flue pressures will cost you $250 or more.  These are the type that, in industrial applications, are mounted with one tube on each side of an air filter, to indicate when the filter is dirty and needs changing (that is, a certain pressure difference across the filter).  Getting one that will withstand flue temps is another matter.


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## DanCorcoran (Nov 17, 2011)

trettig said:
			
		

> I need to test my chimney's draft.  It was suggested to purchase a manometer to test draft.  Does anyone know what manometer I should buy.  I am only going to use it a few times.  So an expensive model doesn't seem to make sense.



I've read your other thread about your difficulties with your stove.   Don't worry about your draft until you first resolve your dry wood question.  The easiest way to do this is to, 1) get yourself the moisture meter others have recommended from Lowes, Harbor Freight, or wherever, then, 2) buy several packs of kiln-dried wood at your local Ace Hardware or Lowes or grocery store.  Take it home, split several pieces, then measure the moisture level on the freshly split surface.  Once you have a stove load or two of known-dry wood (less than 20% moisture), then get your stove up to the temperatures recommended in the other thread (again, you'll need a stove-top or flue thermometer, or both).

The moisture meter and thermometer are inexpensive (compared to the precision manometer you'd need) and both will come in handy as you continue to learn more about burning your stove.  They are also a lot cheaper than replacing your stove, which others-who-have-one say is not going to solve your problem.

If, after all this, you are still having problems, then attack the draft problem.  Wood which is not sufficiently dry is not only the cause of most EPA-approved stove issues, but is also the easiest to diagnose.


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## Battenkiller (Nov 17, 2011)

This is the one you need.  33 bucks.


Dwyer Manometer


Not necessary to get extreme accuracy in this anymore than you do with a stove top thermo.  This manometer will be "eyeball accurate" across the desired range.  If the colored water is between the .05 and .10 markings you should be good according to the manufacturer.

You will need to firmly attach a piece of metal tubing to it if you want to get a reading inside the flue pipe.


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## EJL923 (Nov 17, 2011)

Nice close up.  Your right, it should be good enough to get in the ballpark.


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## backpack09 (Nov 17, 2011)

I would like to say that I would tip that MAN-O-METER off the charts.


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## Battenkiller (Nov 17, 2011)

Backpack09 said:
			
		

> I would like to say that I would tip that MAN-O-METER off the charts.



Really?  I thought the the upper limit was well within the range of "average".  Have I been lied to?   hh:


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## trettig (Nov 18, 2011)

DanCorcoran said:
			
		

> trettig said:
> 
> 
> 
> ...




Thanks again -


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## DanCorcoran (Nov 18, 2011)

Battenkiller said:
			
		

> This is the one you need.  33 bucks.
> 
> 
> Dwyer Manometer
> ...



I think any reading between 0.00 and 0.20 might be good, but you'd never really know.  According to the specs, the accuracy is +/- 3% of full scale, which would be +/- .09.  Thus, you might have zero draft and get a reading of 0.9, or you might have a draft of 0.8 and get a reading of 0.0.  (Edit: see math correction below).

As I understand meters, they are typically most accurate at mid range, which is how you should determine which one to buy.  Using this one at the bottom end would be like using your bathroom scale to determine postage on a small package...not accurate enough to bother with.  I like the idea of the metal tube, though, used with the right manometer.


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## LLigetfa (Nov 18, 2011)

DanCorcoran said:
			
		

> According to the specs, the accuracy is +/- 3% of full scale, which would be +/- *.09*.  Thus, you might have zero draft and get a reading of *0.9*, or you might have a draft of 0.8 and get a reading of 0.0...


Maybe it's just too early in the morning for me to do the math, but aren't you off by a decimal place?


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## DanCorcoran (Nov 18, 2011)

Yes, I was on the last two numbers (which are in the range of a good draft).  It should have said, "According to the specs, the accuracy is +/- 3% of full scale, which would be +/- .09.  Thus, you might have zero draft and get a reading of 0.09, or you might have a draft of 0.08 and get a reading of 0.0â€¦"

Thanks for pointing that out.  My point remains, however, that using the meter at the extreme low end, given the specs, won't tell you anything.


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