would a chimney cap stop downdrafts

[keving]

Its very windy here today (the thumb of michigan)and we notice that once in awhile our fireplace insert will let out a small puff of smoke, would a chimney cap lessen downdraft? Ive cracked open an outside door and it seems to help
there is no visible smoke in the house just the smell of it.this is the first time weve noticed it. we have been burning about four months with zero problems

 

[wkpoor]

I would have to say no.If it could block air from coming down it could block it from going up. My guess is your insert is not being burned hot enough. A cold chimney could do that but not a hot one.

 

[keving]

interesting....It just so happens we let the fire die down during the night and didnt notice a change till I refilled the insert this morning,thanks for the reply

 

[anti TC]

If you don't bother to go outside to smoke, I see no harm in a little fire smoke being in the house? Wouldn't a cap on the chimney allow no smoke from the fireplace to escape outside anyways?

 

[2FatGuys]

To prevent "puffing out" on my insert(s), I usually open the damper fully for a few minutes to allow the coals to re-establish the proper airflow before I open a door. Otherwise, I find that the vaccuum created by the door pulling open will cause a small puff of smoke. It doesn't take much at all to be detectable. The human nose is VERY sensitive to smoke.

 

[habanero]

I would have to say no.If it could block air from coming down it could block it from going up. My guess is your insert is not being burned hot enough. A cold chimney could do that but not a hot one.

There are actually chimney caps designed to prevent downdrafts caused by eddy currents in strong winds. I don't know of any brand names off the top of my head, but I know they exist.

Mom and Dad had this problem with their fireplace several years ago. It wasn't due to a cold chimney, as the chimney could be plenty warm and still if the winds were out of the right direction they'd occasionally get a puff back out of the stove. The problem was there were some trees near the house that had grown tall enough that the wind coming over the top of them created an eddy that would impinge on the chimney.

You can visualize what's happening by looking at a building or fence in a blizzard and watching the snow come over the top and swirl on the backside. When the downward part of that swirl passes over the chimney, you momentarily lose draft and get a puff-back.

I looked into these caps for the parents, but Dad decided to trim the trees back instead and that fixed the probelm.

 

[anti TC]

So if you employ a cap, you're technically a draft dodger? Right?

 

[PaulLovesJamie]

So if you employ a cap, you're technically a draft dodger? Right?

:biggrinbounce2: Ok, that was funny.