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Remedy for a smoking fireplace

BeeDub's picture

I have a fireplace that backs up smoke into the house making it unusable and unsafe.  A fireplace repair contractor came by today and told me that there is an offset in the terracotta chimney liner about 10' down from the top that is the cause of the smoke backup.  To fix it, he wants to install a double wall SS chimney liner in the fireplace chimney and in the furnace chimney and he says this will solve my smoking problem.  The cost will be $3,100.  This doesn't sound reasonable and the cost is way more than I expected to fix this problem.  Is this a reasonable solution to fix my problem?  I would appreciate any and all advice.  Regards,  BeDub

Did he say how much of an (post #206831, reply #1 of 18)

Did he say how much of an offset it is, in what size liner?

It might fix the problem, but most smoky fireplace problems can be solved by assuring there's a good draft.  Warming up the chimney is one key, the other is providing a goodly amount of makeup air.  And a tightly-fitting fireplace door can help quite a bit, especially if the fireplace is over-tall (which is often the case).


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Responding to DanH (post #206831, reply #2 of 18)

The current terracotta liner is 13 x 13.  He said the offset was about 6".  I always get a good draft when starting a new fire; but it seems that when the chimney warms up in 2-3 minutes, then the draft seems to disappear, the smoke billows around the firebox and then comes into the house.  Once that starts, it can't be stopped.  I do have a tight fitting fireplace door already. The house is a ranch style so the chimney is about 18' and clears the roof ridge beam by at least 2'.  BeeDub

How tall is your chimney and (post #206831, reply #3 of 18)

How tall is your chimney and how far above the roof dies it project? You may have a situation where downdrafts are

b;owing down the chimney ot there is a such a big slug of cold air in it that the heat from a fire can't push it out. Next time it happens

Take a piece of newspaper, light it and stick it up the chimney  as far as you can. If that makes the smoke rise then  it's possible you may need to modify your chimney or have hotter fires.

Florida Licensed Building Contractor, 40 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

It sounds like you're drawing (post #206831, reply #4 of 18)

It sounds like you're drawing a vacuum in the house.  Have you tried simply opening a window in the room?


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Need more air (post #206831, reply #5 of 18)

That's my guess...  Or, perhaps, the OP is closing that tight fitting door which has no provision for combustion air.

Need more air (post #206831, reply #6 of 18)

I think you got it right.  When you close the fireplace door, you have cut off the air needed to create a draft. There is probably enough air to support combustion, but thats all. 

Well, (post #206831, reply #9 of 18)

"it seems that when the chimney warms up in 2-3 minutes..."

No masonry chimney warms up that fast. It takes 15-20 minutes of a god hot fire

13x13 for an 18' stack is too large of a flue for most common sized residential fireplaces. So relining smaller might help get the size right.

 

A 6" offset should not be a problem

urious - is this a rough brick flue or a caly fire flue? Rough surfaces create a lot of eddies that can slow movement of the air column

 

 

Oh Well,

We did the best we could...

Reply to All (post #206831, reply #7 of 18)

Thank you all for your ideas.  I have tried all of what has been suggest over the years with no success.

When I try using the fireplace, I never close the doors; I only close the ember screen to prevent pops from coming into the room...so I think there is sufficient air to make the fireplace work.

Berfore starting a fire, I always roll up some newespaper, light it and hold it as far up the chimney as I can to warm up the flue air and make sure there is a draft.

I am sensing from all the feedback so far that the contractors $3,100 solution to reline the chimney isn't going to solve my problem except make me poorer.

A friend of mine gave me a 5" fan and housing designed for high heat applications.  I was thinking of fashioning this into some metal ducting and connecting it to a felxible metal tube that runs from the ash cleanout in my garage to the ash trap in the floor of the fire box as a way to provide a substantial amount of make-up air to the firebox without drawing heated air from the house.  Does anyone out their think such an arrangement would work and would it solve my smoking problerm?  I'd be interested in any and all thoughts.  BeeDub

You didn't mention opening a (post #206831, reply #12 of 18)

You didn't mention opening a window.  The fire starts OK and burns well until it's drawn a vacuum.  Then the fire can't get air, so the draft stops.  The vacuum then pulls cold air down the chimney, blowing smoke into the room.

(I recall the first time we tried our fireplace.  It smoked badly until it occurred to us to open a window.  Later I figured out that I could take advantage of a fresh air intake feeding the adjacent utility room, with a grille between that room and the family room.  The trick is to figure out a makeup air scheme that produces the least mixing fo makeup air with room air, before it gets to the fireplace.)


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Please clarify (post #206831, reply #15 of 18)

You haven't stated whether or not opening a window a few inches in the room with the fireplace will make this smoking problem go away. Don't close the window after the fire starts burning. Knowing the answer would help folks know whether this might be a problem with makeup air and the tightness of the house.

Also, what is the relationship of the furnace flue to the fireplace? Are they entirely separate? Does the furnace fire into this masonry chimney? 

I would not go for your idea of a fan blowing in makeup air. You might look into a chimney-top draft inducer. 

Yeah, the fan blowing makeup (post #206831, reply #16 of 18)

Yeah, the fan blowing makeup air into the pit would blow smoke INTO the room.  The fire needs to be allowed to naturally DRAW it's draft.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

I doubt that lining will fix (post #206831, reply #8 of 18)

I doubt that lining will fix it, but will surely line his pockets nicely.

One clue he is mostly interested in selling for profit instead of fixing the problem is that he is adding in the furnace flue whicch seems to have no problem.


There can be very valid reasons for using a SS liner, but in doing so, you decrease the size of the flue which CAN CAUSE drafting problems. Now if your flue is way too large for the fireplace openning size, that can be a valiud fix because too large of a column of air is hard to move without a roaring fire.

 

The more common problem that causes this is a house that is too tight and no makeup air is available to the draft. Adding an outside air supply to the firebox is the fix for that, but I would need far more info about the whole house and size of fireox, chimney height, flue size, etc to really have an opinion.

 

 

Oh Well,

We did the best we could...

Make up air. (post #206831, reply #10 of 18)

The minimum distance between the highest opening in a fire and the top of a chimney is 16 feet.

The top of a chimney needs to be at least 3 feet above the highest part of the roof.

The supply of make up air needs to be as close to the fire as you can get it (underneath is good)

The best position for a chimney is in the middle of the roof, where it is kept warm by the house.

A warm chimney, will help the cold air to rise.

How does the fire perform when there is a strong wind. 

 

 

 

 

 

 

 

The top of a chimney needs to (post #206831, reply #11 of 18)

The top of a chimney needs to be at least 3 feet above the highest part of the roof.

 

No it doesn't. Code requires a chimney to be 3 feet above any part of the roof 10 feet away horizontally.

See what happens when I get old............ (post #206831, reply #13 of 18)

I had it in my mind it was 2ft higher within 10 of roof.

 

Perry says 16' minimum on initial ht., never knew that one-is that true?

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I would imagine that the (post #206831, reply #14 of 18)

I would imagine that the rules for this have not been totally uniform nationwide, given that is is one of the first things that likely ever made it into code.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

The design of the chimney (post #206831, reply #17 of 18)

The design of the chimney seems NOT to be the problem, and a SS liner may not help much, because, from that way you describe the effect (fireplace drafts well in the beginning, then starts to backdraft), it sounds like the room is being de-pressurized.

De-presurrization could have a number of causes:

1) insufficient makeup air. And "makeup air" includes not only air needed for actual combustion, but also all the air that flows up the chimney along with the smoke and combustion by-products. Test for this by opening a window before you start a fire, as others have suggested already.

2) Insufficient return air to a forced-air furnace from other parts of the house. In that case, a return in same room as the fireplace will "suck" more powerfully and can draw air downward via the chimney. This effect would only happen when the furnace blower is running, so it would be easy to eliminate the possibilty by making sure the furnace blower is not running when there's a fire in the fireplace. 

3) Any exhaust fans that might be running when there's a fire in the fireplace. (Dryer vent, bath or kitchen exhaust fans.) Again, easy to test.

If any of these do not show the problem, then possibly a liner would help.

Venting Issue (post #206831, reply #18 of 18)

Has the fireplace been remodeled lately? As DanH mentioned, often the opening is too tall, but in our area its often too tall because some unknowing soul has ripped off the face and took out the smoke shelf with it. Always surprised by 'a piece of iron' just hanging there (lintel bar)....silly.

If the opening is too tall, the smoke shelf may be missing, in which case would need to be poured back for it to work.