Upgrade question 2

[Bootlegger]

I bought a house 2 years ago with a late 70's Fisher stove. We've used it to heat our home in central Kentucky the last two years. At times we've supplemented with electric heat, but I've pulled out most of the baseboard heating and started the process of replacing old windows, adding insulation and new siding outside, and generally sealing up the house. We'd like to go without any electric heat from this point forward. I have two questions about our upgrade issues. Here is question 2:

Our upstairs fireplace cannot be lit at the same time the downstairs stove is lit. The two flues run side by side in the middle of the house through a massive masonry set of fireplaces (brick downstairs, stone upstairs). The downstairs stove spills smoke when the upstairs fireplace is lit. The sweep told me its because the upstairs fireplace creates a negative air pressure that draws air down the downstairs flue.

In question 1 I asked about my plans to upgrade to two stoves, an insert upstairs and a free standing stove downstairs. The sweep says we are still likely to have the same problem we have now, where one unit pulls in air that has to come from outside and will likely come down the other unit's flue, bringing smoke into the house.

My second question is open-ended: how do I solve this problem?

 

[Jags]

Do these connect to the same flue or do they both have their own flue? That question has to be answered first.

 

[snowtime]

Put an outside air supply on the downstairs stove.

 

[Todd]

Extend the one flue you plan on using the most a foot or so above the other. Outside combustion air will also help.

 

[Bootlegger]

Do these connect to the same flue or do they both have their own flue? That question has to be answered first.

Separate flues, but they run parallel to each other. The one from downstairs has a liner for the wood stove. The one upstairs is 11x17 masonry.

 

[Bootlegger]

Put an outside air supply on the downstairs stove.

That was my first thought but not sure how to vent it to the stove. The stove is in the middle of the room on the main floor. The house is on a slab. Can you run the intake down the chimney next to the flue?

 

[BrotherBart]

PM the webmaster about his product called Extend-A-Flue. Made to handle a problem like this. I have the same problem with my flue in the basement if I am not running both stoves and my flues are offset heights which is supposed to prevent it.

Do you have a single large cap covering both flues?

 

[Bootlegger]

PM the webmaster about his product called Extend-A-Flue. Made to handle a problem like this. I have the same problem with my flue in the basement if I am not running both stoves and my flues are offset heights which is supposed to prevent it.

Do you have a single large cap covering both flues?

Yes, one cap covering the top of the entire rectangular chimney but I would have no problem taking it off, extending one flue and capping each separately. Should the downstairs flue be the higher one?

 

[Bootlegger]

Put an outside air supply on the downstairs stove.

That was my first thought but not sure how to vent it to the stove. The stove is in the middle of the room on the main floor. The house is on a slab. Can you run the intake down the chimney next to the flue?

cant be inside the flue & the airflow in the length of the intake pipe may be constricted by the length of the run. talked to local codemaster lately?

Codes? What codes? (can't play dumb here can I?)
The intake would run next to the venting flue, but inside the same chimney. Intakes a 4" while the vent is 6", right? Chimney is 11x17.

 

[Bootlegger]

Has anyone tried the Exhausto chimney fan advertised at the bottom of the page?

 

[BrotherBart]

Has anyone tried the Exhausto chimney fan advertised at the bottom of the page?

Look at the price of it and you will get over it quickly.

You want the upstairs flue higher than the downstairs flue. Quite possibly just getting them off the same cap will do the job but while you are at it raise that upstairs flue up over the one downstairs. Shared caps are notorious for this problem.

 

[Bootlegger]

Has anyone tried the Exhausto chimney fan advertised at the bottom of the page?

Look at the price of it and you will get over it quickly.

You want the upstairs flue higher than the downstairs flue. Quite possibly just getting them off the same cap will do the job but while you are at it raise that upstairs flue up over the one downstairs. Shared caps are notorious for this problem.

Righteous sir, parsimonious and inexpensive, thank you.
After the work is done I'll report on the findings.

 

[learnin to burn]

BB - "You want the upstairs flue higher than the downstairs flue."
Yep I agree.

Also from question 1 you were considering an insert for the fire place - If you put an insert in up stairs with an Outside Air Kit you would solve the problem of pulling air in through the other unit. I think you still need to extend the upstairs flue though.

 

[Todd]

Why should he extend the upstairs flue if he's burning the downstairs flue most of the time? Extend the flue you plan on using most to get the smoke well above the other. I had this problem and that's what I did, problem solved.

 

[North of 60]

Why should he extend the upstairs flue if he's burning the downstairs flue most of the time? Extend the flue you plan on using most to get the smoke well above the other. I had this problem and that's what I did, problem solved.

He says the problem is when they are both lit. Its not pulling smoke down from the other flue. The negative is causing the smoke to come out of the stove that is also operating. Since the stove is in the middle and slab on grade and you have spent $ on insulating and upgrading windows... Id spend a little more $ and install a HRV unit to create a positive in the home or possibly if an insert is installed upstairs it will draft less and it could be fed the OAK easier. :coolhmm:

 

[Bootlegger]

Great ideas folks. I will extend the bottom flue when I do the upgrade and put them under separate caps. I think for now I'm going to replace the Fisher (maybe put it in my future workshop) with an Englander as Lowes has a great price on the 3.5 cf unit ($999).

One issue, my current venting is for a rear vented stove and goes up through the existing brick fireplace downstairs. Can I install a top vent stove to a rear vent flue system?

 

[crazy_dan]

a picture of the connection from the stove in to the chimney would help a lot.

 

[Wet1]

Mod the flue as mentioned. I'd still find a way to install an OAK on the lower stove. With two going you're creating a lot of negative pressure in the house. My guess is the lower you would benefit from installing an OAK even w/o the upper running.

 

[Bootlegger]

a picture of the connection from the stove in to the chimney would help a lot.

I'll try to get a pic this evening. It's an ordinary brick fireplace, at ground level, with a large brick hearth. The stove is on the hearth, vented straight out the back and up the existing chimney. There is a plate of steel filling the fireplace opening through which the vent pipe passes.

 

[oconnor]

The flue extender will likely keep the smoke out of the house, but not the cold air that is drawing the smoke in with it. Adjacent fireplaces often have this problem - best option is to better seal the damper in the offending fireplace - ideally block it off all together, as most fireplaces don't add much heat to the home anyways.

 

[Bootlegger]

The flue extender will likely keep the smoke out of the house, but not the cold air that is drawing the smoke in with it. Adjacent fireplaces often have this problem - best option is to better seal the damper in the offending fireplace - ideally block it off all together, as most fireplaces don't add much heat to the home anyways.

How does one seal a flue or block off a chimney?

 

[BrotherBart]

The flue extender will likely keep the smoke out of the house, but not the cold air that is drawing the smoke in with it. Adjacent fireplaces often have this problem - best option is to better seal the damper in the offending fireplace - ideally block it off all together, as most fireplaces don't add much heat to the home anyways.

How does one seal a flue or block off a chimney?

(broken link removed to http://www.chimneyballoon.us/chimneyballoon.html)

Or just stuff an old blanket in it but leave something hanging down so a quest doesn't decide to welcome you home with a nice fire and smoke up the joint.

 

[oconnor]

The flue extender will likely keep the smoke out of the house, but not the cold air that is drawing the smoke in with it. Adjacent fireplaces often have this problem - best option is to better seal the damper in the offending fireplace - ideally block it off all together, as most fireplaces don't add much heat to the home anyways.

How does one seal a flue or block off a chimney?

If you plan on installing a stove in the upstairs fireplace - likely an insert - you shouldn't have the same issues as you do know, given that a new EPA stove with a full liner, properly installed, isn't going to allow the same volume of air to draft down the flue as you are getting now.

Give the "Guide to Residential Wood Heating" in my signature block a read thru. There is a section in there covering what you are experiencing.

 

[BrotherBart]

If you plan on installing a stove in the upstairs fireplace - likely an insert - you shouldn't have the same issues as you do know, given that a new EPA stove with a full liner, properly installed, isn't going to allow the same volume of air to draft down the flue as you are getting now.

Don't be so sure. I went for decades without it happening, until I put the two liners and EPA stoves in.