I am having a problem with a 2 sided fireplace in new house we built last year. It is on top of a hill and windy much of the time. We have installed a glass door on one side and left the other side open. It is a brick chimney with 3 flues (1 woodstove, 1 boiler and 1 for the fireplace. It has a direct fresh air supply to the outside via a sliding grate on the bottom of the firebox. It burns nicely most of the time but sudddenly it will let out a puff of smoke. Because it does this every few minutes, after and hour or so, the 2nd floor of the house smells smokey.
I was wondering if anyone has suggestions. Has anyone used a Exhausto chimney fan and if so, how do they work? I hate to have to put one on top of a large colonial chimney stack, but if it is the answer so be it
Edited 4/9/2002 3:35:08 PM ET by Ken
Replies
Ken,
Your problem is caused by downdraft and can be cured simply with a chimney cowl.
Here's a link for you to a firm that sells chimney cowls
Unfortunately they don't look too pretty -- there is an alternative made out of terracotta which fits in the top of the flue and looks like a louvred chimney pot but I can't find a URL for you. Perhaps you can search for it if you don't like the look of the metal ones.
IDG.
Edited 4/9/2002 3:57:21 PM ET by IanG
Been here before and had luck with adding a "smoke curtain" to the top of the hearth opening. The correct size can be experimentally derived by using hemmed pieces of aluminum flashing of assorted drop lengths and holding temporarily in the top opening of the hearth.
It seems that in most cases the flue size was marginally adequate and fluctuations in the house's atmospheric pressure caused smoke to belch. You can actually lay on the floor and look up into the smike chamber of the fireplace while a smoky fire burns and watch the undulations of the smoke and eventually a "belch."
The maximum ratio of heath intake area to flue cross section area is 8 sq in: 1 sq in. Try a calculation on your set up and see where it falls. A "smoke curtain" reduces the area of the hearth intake.
Try it ...it may save you some smoke and $$$..........................Iron Helix
Ken,
As an architect, I know when we do residential house (which I have not done one in about 10 years, my office does all commercial) I know there is a certain distance the chimney needs to rise over any and out from any adjacent roof ridge. I don't know the rule of thumb to base the height of the chimney flue versus the distance from the roof ridge off hand, and I really don't know your chimney to roof situation, but I know this type of problem can cause a chimney to not draw correctly. That my two cents worth. Good luck, Eric
ecomma,In the UK it's a minimum distance of 3' from ridge to top of chimney pot, but that by itself doesn't guarantee no downdrafts.
Overhanging trees, surrounding land formation, wind strength and direction, etc., will all affect the draw.
Providing the Hearth/Flue is correctly constructed, I've never known a problem that WASN'T solved by fitting some type of cowl or other though.IDG.IDG.