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Old 02-01-2010, 10:33 PM   #16
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Chimney Drafting Seems Un-Solveable


You had a blower door test done. And they couldn't find any significant air leakage?
Was this one of those $100.00 foot in the door test?

If you got this much down draft from your chimney. They should have had trouble even doing a BD test.
You might have been horn swagged on that test. You might have more issues then they knew how to deal with.

What size is your boiler?

Are those the inside dimensions of your chimney, or of the fire place?

That chimney if its not high enough above the roof line. Will be in a positive pressure zone. And you can end up with a down draft no matter how tight you seal the rest of the house.

When you do that test. After you checked for all other possible causes of the down draft. And if you can't find any.
Take the plastic off that fireplace, before you take the plastic off the boiler room. If you still have a strong down draft with the boiler room sealed. there is a REAL good chance that the chimney not being far enough above the roof line is what is causing your problems.

You may need a chimney guy to come in a verify that it is the chimney in that case. Not just a mason. But an actual certified chimney inspector.

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Old 02-02-2010, 03:01 PM   #17
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Chimney Drafting Seems Un-Solveable


My thinkin exactly. The chimney may need to be extended and depending on the roof line(s) /prevailing winds/trees you can get eddy currents/swirling and affect the chimney. Another trick you can use ( we use in office bldgs to check air currents for complaining staff) is to get some dry ice, let it create "smoke" and you can see your air patterns/currents in the house.
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Old 02-02-2010, 03:37 PM   #18
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Chimney Drafting Seems Un-Solveable


You just like to make fog.
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Old 02-02-2010, 03:57 PM   #19
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Chimney Drafting Seems Un-Solveable


Only on "chili" nights. And I ain't talkin about the weather.
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Old 02-03-2010, 11:00 AM   #20
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Chimney Drafting Seems Un-Solveable


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My thinkin exactly. The chimney may need to be extended and depending on the roof line(s) /prevailing winds/trees you can get eddy currents/swirling and affect the chimney.
Yep yep... exactly! But, if the chimney is extended, because of the improved draft he'll still need a supply of air. Keep the window open I guess.
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Old 02-03-2010, 02:31 PM   #21
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Chimney Drafting Seems Un-Solveable


Motorized damper on the boiler flue. When the damper opens the end switch turns the draft inducer on. No big deal. Do it all the time on commercial applications.
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Old 02-03-2010, 03:17 PM   #22
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Chimney Drafting Seems Un-Solveable


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Motorized damper on the boiler flue. When the damper opens the end switch turns the draft inducer on. No big deal. Do it all the time on commercial applications.
Ok.

So your recommending that he installs a motorized damper on his boiler.
And then have its end switch run an inducer that he needs to install in his fireplace chimney. So that the fireplace now draws air out. Instead of the fireplace down drafting.

Since he isn't having a problem with teh boiler or its chimney not having enough draft.
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Old 02-03-2010, 03:51 PM   #23
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Chimney Drafting Seems Un-Solveable


Chimneys can be a nasty complicated business. The one from the boiler may be updrafting nicely as it is higher than the other one. They may both need to be a matched size and height to have equal draft/function. He has a combustion air pipe to the boiler room to bring air in. Hopefully it is the right size. How big is it/diameter?
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Old 02-04-2010, 10:15 AM   #24
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Chimney Drafting Seems Un-Solveable


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Motorized damper on the boiler flue. When the damper opens the end switch turns the draft inducer on. No big deal. Do it all the time on commercial applications.

So, the draft inducer draws air from outside?
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Old 02-07-2010, 09:56 AM   #25
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Chimney Drafting Seems Un-Solveable


Ok, so further testing done..and thank you again for all the posts.

I turned off the boiler and the air handler and sealed up the boiler room.

Not much of a difference. The fire place mostly drafts into the house, but occasionally it drafts out of chimney. It kind of "breathes", but the majority is drafting in the house, which is virtually the same as with the boiler on.

I sealed my attic door - no difference.

I also noticed that any door I closed on my second floor seemed to be pulling air. If I put plastic against the door it would pull the plastic against it. And that was any single door, so I don't know if that is normal or not.

Another test - window opening
1) opening in basement and first floor would make the chimney draft out of the chimney
2) opening a window on the second floor - no affect
I actually could feel when I opened the window on the second floor that the air was not rushing in like it does below.

Regarding the two chimney's:
the are not the same heights
The one that shares a flue with the boiler and is drafting to the outside always is higher.
The other one, where the problem is is shorter

Once again I appreciate everyone's comments, though I'm not sure what to do to fix the problem still. Does anyone think there is anything conclusive here?
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Old 02-07-2010, 10:18 AM   #26
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Chimney Drafting Seems Un-Solveable


Still sounds like the house is acting like a chimney to me. If the doors on the 2nd floor are sucking in the plastic then thoughs rooms are the exhaust. They cant suck air in with out exhausting air out. You need to find the leaks in the rooms and seal them. Use a smoke candle or blow matches out and watch the smoke were it exits the rooms.

A cigerate works if you smoke.

Last edited by JohnH1; 02-07-2010 at 10:20 AM. Reason: Idea
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Old 02-07-2010, 10:20 AM   #27
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Chimney Drafting Seems Un-Solveable


Conclusive? Not yet.

Is your duct work for the second floor in the attic? I ask because you said you have a negative pressure in those rooms. So your duct work if its in the attic could have some holes in it. Which could cause some of your draft problem.

You probably need your chimney extended. This is something a chimney guy needs to check and verify though.
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Old 02-07-2010, 11:27 AM   #28
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Chimney Drafting Seems Un-Solveable


This is actually a physics problem, and you already found the solution. If opening the basement window "solves" the problem, so to speak, then you've actually solved the problem. The boiler and/or its chimney is using your house as its air intake. It will pull air from any opening to the outside, including the "problem" chimney. Four floors, and you can create a HUGE vacuum!

To check out whether I'm right, stop the boiler and close its chimney, and see if the problem goes away. If it does, then the simple solution is to provide a separate intake for the boiler direct from the outside air. If it doesn't, then you have a different problem, a huge air leak allowing air into the attic (or roof, or whatever) which is creating the vacuum.

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Old 02-07-2010, 11:32 AM   #29
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Originally Posted by joncampbell View Post
This is actually a physics problem, and you already found the solution. If opening the basement window "solves" the problem, so to speak, then you've actually solved the problem. The boiler and/or its chimney is using your house as its air intake. It will pull air from any opening to the outside, including the "problem" chimney. Four floors, and you can create a HUGE vacuum!

To check out whether I'm right, stop the boiler and close its chimney, and see if the problem goes away. If it does, then the simple solution is to provide a separate intake for the boiler direct from the outside air. If it doesn't, then you have a different problem, a huge air leak allowing air into the attic (or roof, or whatever) which is creating the vacuum.

Regards
Jonathan
pretty sure he already posted that they added a air intake in the boiler room already.
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Old 02-07-2010, 11:45 AM   #30
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Chimney Drafting Seems Un-Solveable


I am already providing a fair amount of air to the boiler room via 2 methods:

1) I have a plus air system that takes air from the outside and puts into to the air handler directly
2) I have a open air vent directly from the outside that vents close to the boiler.

In regards to the questions about the 2nd floor. The duct work is indeed in the attic, but most of it is covered as it is finished on that floor. The doors were drawing, but as a test I closed a door on the 1st floor and it had the same effect, it gently pulled the plastic from it. I'm wondering if that is common.

What really baffles me if it is indeed the height of the chimney is why it "breathes." How can sometimes it draw into the house and other times draw out of the house? Today seems to be particularly windy and the breathing is more pronounced than usual.

In regards to air leaks throughout house. Would one way to test that to be to seal all the doorways with plastic upstairs and see if it solves the problem? I have a feeling it won't do anything b/c I covered one and saw no difference. But if the air leak is under some covered portion does anyone have any suggestions on tests I could do to better pinpoint it?

As I mentioned I did have a blower test done, but it was cheap as it was done as part of the state's energy conservation program and I only had to pay a nominal fee to have it done. They found nothing however in regards to leaks.

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