To: "Leggett, David"
From: Jim Buckley
Subject: RE: Stacked Rumfords-upper sucking smoke from lower
Great looking fireplace. Thanks for the picture.
From your comments below any of the factors you mention could be the problem. If I had to pick the most likely it would be the two large returns, both in the ceilings of upstairs hallways.
But my most important advice is to get some incense and test out these theories as outlined at http://www.rumford.com/smoky.html. Does air come down the bedroom fireplace chimney? How about when the furnace is on and does the incense smoke indicate it goes into the return vents? For sure try to open the combustion air vents in the firebox but check with the incense to see if air comes in or goes out. Typically the big problem with combustion air in bedroom fireplaces - beside not being adequate in the first place - is that the upstairs part of a house is usually positively pressured and the air flows backward out through the combustion air vents. And that could be a fire hazard.
Let me know what you find,
Subject: Stacked Rumfords-upper sucking smoke from lower
Date: Mon, 7 Jan 2008
From: "Leggett, David"
To: "Jim Buckley"
Jim, thanks for your reply.
There are bathroom fans throughout the house, and there are four baths, one in the basement, one on the first floor, and two on the second. The master bath has two such fans. In addition, there is a kitchen range fan. But all of these are small fans, and none of them is used very much, and none have been running at all when this problem is occurring. It might be interesting sometime to fire them all up at once, just to see if I can make the great room Rumford smoke!
There is a two-zone heating forced air gas heating system in the house. The original basement furnace heats the basement, first floor and one of the second floor bathrooms. There are generally heating vents in each room, with separate returns, except the great room has two large returns, one near the floor and one higher in the wall. The thermostat for this zone is near these returns. I should have had it put somewhere else, and may yet do so, as the Rumford in the great room is easily able to shut down this entire zone, as it raises the temp at the thermostat to 75 degrees with no difficulty. Whoever said fireplaces were negative energy providers never saw my Rumford, which can go a long way toward heating the first floor of the house!
The second zone covers the rest of the second floor, including the master bedroom, and the heat comes through the ceiling from the furnace in the attic through flexible insulated ducts. There are two large returns, both in the ceilings of upstairs hallways, one in the old part of the house, and one in the master suite, about 15 feet from the Rumford. Don't know if this is a factor.
Both Rumfords have small outside air vents through the rear of the firebox, as they were required by code. Keeping in mind the problems you have cited from such vents, I have always kept them closed, and they are hidden behind the tall cast iron fire backs which sure have saved the ordinary brick of the fireboxes. I am wondering now why I just shouldn't try opening these up, and see what happens. Your site seems to say these vents are most tricky on second floors, but the problems you cite seem only to occur when the fireplace is in use, and as mine is not used much, maybe it would be ok. Any thoughts if I should open just one, or both? This is the quickest way I can think of to get a bit more air into the house, without leaving windows or doors open. Otherwise, it seems that one is dealing with air handlers, which are awfully expensive. Any thoughts on non-drafty, secure solutions that don't involve sale of my first-born? Just for grins, I have attached a photo of the great room Rumford. I call it Count Rumford goes to Athens. I will have to send one of the second floor (identical fireplace, but somewhat different mantel planned) as soon as I finish playing carpenter up there.
Nice to hear from you again. It is an odd situation. It'a much more common for smoke to be drawn down a flue that vents a fireplace in the basement or first floor where the indoor air pressure is usually the most negative.
Anyway, the smoke comes down any chimney only because the pressure at the bottom - in this case your bedroom - is less than it is at the top of the chimney. Have you got a big fan in that room or a furnace air return? Try opening a window in the bedroom to neutralize the pressure and see if that stops the downdraft. If it does, you just need to find a non drafty way to let some more ventilation air in the house - maybe down low in the mechanical room or over heated laundry area.
If I didn't mention it before, read through the smoky fireplace check list at http://www.rumford.com/smoky.html, get a stick of incense and see what the relative air pressures are and how the air moves in your house.
Air or smoke comes down your chimney due to lower air pressure in the house than outside. Adding more ventilation air will fix it. Whatever you might do to the top of the chimney will only treat the symptoms - not fix the problem.
Let me know how you fix it or if you have more questions.
[Back to Technical Discussion]
Buckley Rumford Fireplaces
Copyright 1996 - 2009 Jim Buckley
All rights reserved.