Do I need/How to install flue damper?

[nola mike]

Hope to finish the install tomorrow...
Have an old Jotul 602 that I'll be installing in a coal fireplace. Just swept the chimney and installed the 5" x 30' liner today. Do I need a flue damper? I bought one like this: (broken link removed to http://www.stovax.com/images/acc_vent_fluedampers_ac_1.jpg)
the liner will go into an adapter like so: http://www.chimneylinerdepot.com/store/catalog/linercoupler.jpg

So, if I should install one, how do they install? Do I drill a hole in the liner, or the adapter, and just thread the metal rod through? I don't have room in the install to put in any stove pipe, and won't have a ton of access to the liner once the stove is in place...

 

[snowtime]

typically a key damper is installed above the stove in a section of stove pipe. I would not put a damper in your liner. There are many possible problems with that but the biggest by far is that you can not take it out easily to clean chimney. Most people do not use or need one so just forget it.

 

[KeithO]

Only needed for long vertical runs where the chimney is a) well insulated from outside cold, b) in constant use thus not cold c)vertical height exceeds a critical threshold for your stove (draft is too high to permit control via the inlet air control on the stove.

My chimney is a 9-10ft run of single wall stovepipe inside my great room (puts out a lot of heat), then meets the class A at the ceiling, followed by another 7-8ft of class A in the attic where it is not quite as cold as outside + the final 3-4ft above the roof line. So I have at least 20-21ft of vertical rise and most of it is in insulated space. The only place I collect a deposit in my flue is the last 4 feet that is out in the weather.

My chimney was an absolute pain until I put in a flue damper and it could stand a second one 6 ft above the first. With the current cold weather and big temperature differential, even with the flue damper fully closed, I still have way more draft than I need on my T5. I bonded a 1/4" washer over the air wash inlet with stove cement to reduce the cross section by about 4x and have ground back the stop on the air inlet control so that it can shut all the way. The thing with excessive draft is that the more you close up the leaks, the harder it pulls on the ones left, like the secondary air inlet. Really, it is far better to leave the stove alone and just choke down the chimney until it behaves. Unfortunately, as mentioned, flue dampers do create service issues. In my case, I don't even run the brush down to the damper anymore, since I know the stovepipe is clean, so the main thing is to be sure the dampers are open when you clean above on the roof.

I did have a bird get through my chimney cap and fall down the flue and that really was a pain to get out....

 

[begreen]

I think you will need it. Our 602 draws well on about 12 ft of pipe and I found a key damper helpful even then. In order to install one I expect you will need to come off the back of the stove with an elbow, then a 12" length of rigid pipe in which the key damper is installed, then the liner.

 

[nola mike]

I think you will need it. Our 602 draws well on about 12 ft of pipe and I found a key damper helpful even then. In order to install one I expect you will need to come off the back of the stove with an elbow, then a 12" length of rigid pipe in which the key damper is installed, then the liner.

hmm, that would really bugger what I'm trying to do. The stove needs to sit in the fireplace (the room/hearth are REAL small) and exit from the top. As I said, I don't think I'll have room for the stovepipe; actually, I wouldn't have room even exiting from the rear. Is there an issue with installing it directly in the liner? It would be a bit difficult to get to (but not impossible), and would simplify the install...

 

[begreen]

No problem if it's top exit, the principle is the same. Just skip the elbow. I don't think the liner is tough enough to support the damper or deal with it's daily operation. I think it would tear and leak pretty quickly.

 

[nola mike]

No problem if it's top exit, the principle is the same. Just skip the elbow. I don't think the liner is tough enough to support the damper or deal with it's daily operation. I think it would tear and leak pretty quickly.

good point. If I install stove pipe, I'll have to pull the liner/pipe joint up into the chimney (where it will be inaccessible), which I guess isn't a huge deal. I'll also need to see if I'll have enough flexibility with the pipe in to make the terminal connection to the stove--it's going to be a tight fit as it is. All I really need though is enough pipe for the damper to mount in--I would think 4" should be plenty. Last (biggest?) issue will be if I can find another coupler for the pipe connection locally. Now, is this damper something that needs regular adjustment, or can I just get it right once, and leave it?

 

[KeithO]

Open damper fully before opening the stove door, else smoke will pour into the room. Reload the stove, get it cranking, close the primary air some, then when stable fully close the damper. Give the stove time to adjust, then adjust the primary air to the right point. Between the damper and primary air you get to set how much primary vs secondary air you will have. Damper open + primary fully closed = lots of air through the airwash and the normal amount of secondary. Damper closed + primary slightly open = less secondary air. For instance when burning down coals, lots of secondary air is not your friend.

So the answer is, you are going to be working the damper every time you need to open the door to the stove, which is often. If location is a hassle, you could fit it high enough in the masonry chimney that you can drill a hole through the brick to fit an external handle. Of course everything will have to line up just right...

Good luck

 

[begreen]

No problem if it's top exit, the principle is the same. Just skip the elbow. I don't think the liner is tough enough to support the damper or deal with it's daily operation. I think it would tear and leak pretty quickly.

good point. If I install stove pipe, I'll have to pull the liner/pipe joint up into the chimney (where it will be inaccessible), which I guess isn't a huge deal. I'll also need to see if I'll have enough flexibility with the pipe in to make the terminal connection to the stove--it's going to be a tight fit as it is. All I really need though is enough pipe for the damper to mount in--I would think 4" should be plenty. Last (biggest?) issue will be if I can find another coupler for the pipe connection locally. Now, is this damper something that needs regular adjustment, or can I just get it right once, and leave it?

The damper will need a minimum of 6" pipe length so that it can swing full range and not get hung up on anything like a crimp or attaching screws. I would use at least 8" of pipe.

We always opened the damper to start the stove, but you will have to experiment. If your draft is very strong during cold weather you may be able to run with it partially or all the way closed, all the time. In mild weather I suspect you'll need to open it for starting. You can never close it off fully. There are holes in it to prevent blocking draft completely. Point the handle to the front so that it remains very accessible.