Quad 4300 Step Top: Smoke spillage

[richg]

Gang:

I hope you are doing well. I have fired up a new 4300 step top a few times of late, and was disappointed at the amount of smoke spillage, both on startup and while the stove is running. The glass is getting very dirty as well. Here is the setup:

2010 Quad 4300 Step Top
Outside Air kit
Chimney: double-wall Selkirk
Stove Pipe: Double wall selkirk
Runs: 3 feet up from flue collar to a 90-degree bend, 2 feet horizontal into the thimble, outside the chimney goes 17 feet up to the cap.
Obstructions: None-chimney is clean as a whistle, no birds nests creosote etc

I had a 2100 on this chimney last year and it vented like a champ. Is it possible that the still (relatively) warm temps and high winds are doing this? My dealer can't help. Any advice would be appreciated, thanks.

PS: instead of a 90, what about 2 45's?

 

[webbie]

My guess is that some is due to the weather. Chimneys will get stronger as the weather cools (the differential between inside and outside is greater).

However, your chimney is marginal and can probably be improved as you mention....

A rough calc works like this - each 90 degree bend takes 5-6 feet off the effective height of the chimney. Min. chimney height for most stoves is about 13-14 feet.

So, take 10 off your 17 and you have a 7 foot chimney!

Yes, I think the flow about be better to use adjustable els or 45's to eliminate that 90. Also, make 100% sure that have sealed all joints between the pipes and at the stove with furnace cement. Lastly, you might want to add a couple feet to the top of the chimney if things do not improve enough otherwise.

 

[Backwoods Savage]

Craig, I thought the elbow took away 3' rather than 5-6 feet, but you may have been talking about both elbows.

In addition to the 45's your horizontal section should have a minimum of 1/4" rise per foot of horizontal. We did ours at about 1/2" rise per foot. With this said, I will also add that our chimney is way too short in theory. In practice, it works very well.

 

[webbie]

I've seen figures as low as 2 feet and as high as 6 feet for each 90 degree. I think it depends on a lot of things...for instance, the ID of the vent, whether the turn is on a chimney (insulated) or on black pipe, etc.
In other words, it combines with other factors! It also differs with various fuels and types of combustion - that is, oil or pellet which is partially fan forced, as opposed to wood or even gas (DV or BV) which is 100% natural draft.

Rather than overcompensate, a figure of about 4 feet for a 90 and 1 foot for a 45 might be in the ball park.

It's all the little things which often add up. This seems to be an exterior chimney, which takes a bit off the draft.

In the real world, I've seen 10 foot (stove to top) straight up chimneys through a flat roof do better than 30 foot exterior chimneys from a basement all the way up....with a couple inside els! Too cold.......to ever warm up.

 

[Backwoods Savage]

Right on. Probably better to figure on the high side rather than too short.

 

[oldspark]

If that is the case my chimney is marginal but it works well even in the warmer weather, results vary a lot it seems. What is the difference between the stove you have now and the one you had last year?

 

[richg]

Oldspark:

Last year I had a Quad 2100 on this chimney setup. The 2100 is their smallest stove and I had no issues with smoke spillage when the door was opened. The new stove is a 4300 Step Top which is the 2nd largest one they make.

Today I added another 3 feet of pipe on the outside, and put stove cement on the stove pipe joints that do not need to come apart for cleaning. It's curing now and I may fire it up later today. Thanks for the input gents.

 

[richg]

I LOVE HEARTH.COM!!

Gents,

As noted, yesterday I followed Craig's advice and modified the vent system. What I found was that the Selkirk flue adapter was 5.5 inches in diameter whereas teh Quad flue is 6 inches....there was obviously a 1/4 inch gap all the way around that was hindering draft. I cemented gasket around the pipe for a tigh tfit. Then I sealed the pipe joints which were not needed for disassembly, added 3 feet of chimney pipe, and the problem is solved. There was an anology in anotehr thread that if your venting system is porous, it is like trying to drink a thick milkshake through a straw that has a hole in it. Best of all, the stove is burning much hotter, cleaner and the flames are doing wild displays that are quite a treat to watch.

Thanks again for the advice, and happy burning!