Smoke comes out when opening fireplace door

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sjamesc

New Member
Dec 7, 2020
6
Ontario Canada
We have a 2 door BIS 1.2 ZC fireplace. When adding firewood, I usually only open one door. However, if I also open the second door (part way) a lot of smoke (and some ash) escapes into the room. What is causing this to happen? I ask because we are thinking of replacing our unit with a new single door fireplace and I fear I'll have constant problems with smoke whenever I add firewood. Do other people have this problem with single door units?
 

begreen

Mooderator
Staff member
Nov 18, 2005
91,301
South Puget Sound, WA
When was the chimney and cap last cleaned?
 

begreen

Mooderator
Staff member
Nov 18, 2005
91,301
South Puget Sound, WA
There are several factors that can cause this. A cap or chimney that needs cleaning, a negative pressure location, relatively warm outside temperatures, and sometimes, poor design. Make sure that none of these are the cause before replacing to remedy.
 

begreen

Mooderator
Staff member
Nov 18, 2005
91,301
South Puget Sound, WA
Does the fireplace have an outside air connection? Is this a first-floor or basement installation?
 

begreen

Mooderator
Staff member
Nov 18, 2005
91,301
South Puget Sound, WA
Does the problem occur on a cold winter day or just in milder weather?

Check the outside air supply to make sure it is not blocked by anything. There are some factors that can create negative pressure in the room. A strong kitchen exhaust fan running, an open window or attic vent or bathroom exhaust fan running on a second floor can reduce pressure in the rooms below. One test that may help is to open a nearby door or window an inch and see if that helps.
 

sjamesc

New Member
Dec 7, 2020
6
Ontario Canada
Does the problem occur on a cold winter day or just in milder weather?

Check the outside air supply to make sure it is not blocked by anything. There are some factors that can create negative pressure in the room. A strong kitchen exhaust fan running, an open window or attic vent or bathroom exhaust fan running on a second floor can reduce pressure in the rooms below. One test that may help is to open a nearby door or window an inch and see if that helps.
Thanks for those tips. I'll give that a try.
 

Charby

New Member
Mar 17, 2021
4
1000 Islands, ON
I usually keep it open a fair bit. But I haven't checked for obstructions. I'll check that.
We just bought a house within the year with a Bis 1.2 and have looked at manual with the following questions:
I have outside air coming in but not sure of what the control lever does or position it is to be in?
It is a a vertical arm on left side of fan compartment underneath box.
The 2 side levers operation in front are confusing too or doe the do anything?
 

begreen

Mooderator
Staff member
Nov 18, 2005
91,301
South Puget Sound, WA
I am reaching back a bit in tired memory cells, but I think the manual should show that the left hand control is the primary air control. Move it to the left to increase air to the fire. The center control is for starting the fire and called the boost air control. This has a delay timer on it that you set according to how dry the wood is and how strong the draft is. In mild weather the fireplace may work better with it more open and in very cold weather it may work better with it less open. This control is move to the right to open. It is normally only used for a cold startup, not a reload. Moving it to the left closes it off. If the chimney draft is strong and the firewood is nice and dry it may not be needed and the control can stay to the left. The manual should have all of this information in it. Please refer back to this as it's been many years since I last visited this fireplace.
I don't know what the other lever is. This may be an add-on valve closing off the fresh air intake? Normally there isn't one, but perhaps the installer added it. If so, it will have to be determined what is the open position. The fresh air supply must be open to operate the fireplace.
 
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Charby

New Member
Mar 17, 2021
4
1000 Islands, ON
I am reaching back a bit in tired memory cells, but I think the manual should show that the left hand control is the primary air control. Move it to the left to increase air to the fire. The center control is for starting the fire and called the boost air control. This has a delay timer on it that you set according to how dry the wood is and how strong the draft is. In mild weather the fireplace may work better with it more open and in very cold weather it may work better with it less open. This control is move to the right to open. It is normally only used for a cold startup, not a reload. Moving it to the left closes it off. If the chimney draft is strong and the firewood is nice and dry it may not be needed and the control can stay to the left. The manual should have all of this information in it. Please refer back to this as it's been many years since I last visited this fireplace.
I don't know what the other lever is. This may be an add-on valve closing off the fresh air intake? Normally there isn't one, but perhaps the installer added it. If so, it will have to be determined what is the open position. The fresh air supply must be open to operate the fireplace.
Thanks for the advice, and with further investigation of the front controls, something may have been changed in mine.
The left control when moved to the right opens air ports underneath as I can feel them. This was also evident when the fire is at the right burn rate that I can see a difference in flame dancing when moving it in the open and closed direction. The right side seems to be the same type of control as its mechanical slider and only use it to get it started as you mentioned. Manual says it operates as a booster on a timer, but mine is totally mechanical and would not shut off on its own. There is an outside air supply pipe in basement leading to the fireplace and there is a vertical lever control (which doesn't do anything) on left side under front panel. There must have been a fan setup at one time as I see 2 house wires coming in lower panel on right and cut off. There is no power and don't know when there is a switch. Can't get access to the area in basement, as it would be nice to move the hot air out.
Some of these issues could be on others.