Top or rear vent?

[Dave P]

The info. on my new wood stove shows a significant drop in efficiency when vented from the back vs. the top. My problem is venting through the top will mean another elbow or a total of two. Would the additional elbow negate some of the advantages of the top vent?

 

[Corie]

Significant drop? What wood stove do you have? I'm trying to think of a company that posts efficiency numbers for top and rear vent, but I'm having a hard time thinking of one? It makes me wonder....



Anyway yes, to answer your question if you need another elbow if you top vent, you're probably back to the rear vent performance point.

 

[Dave P]

Thanks Corie,
The stove is Scan Anderson and the spec.'s from the company gives a sq.' heating capacity for top vent 1200 sq.' and rear down to 900sq.' I'm not sure how much faith to put in those numbers. Rear vent would look alot better but that's quite a drop.

 

[Corie]

Whoa! That is quite a drop.


Would it be a real killer to hook it up rear vent first and see what happens and then if the performance stinks, switch it over to top vent? That's what I might do. I don't think I believe those numbers 100% though, loosing 300 square feet of heating capability means a serious loss of efficiency and makes me wonder if the stove would even pass as a rear vent, ya know?

 

[elkimmeg]

I wonder what every extra 90 degree elbow does to effeciency so you have a top venter with 2 90's and the stove preforms worse that the rear exit and on 90 or better yet a tee.

Do they tell you the % of stove performance drop due the friction caused in the curbed section of the connector pipe?

I admit that is a huge drop in performance. Never heard it expressed like that before

 

[Dave P]

No Elk, they don't provide that kind of detailed info. I think you are probably right in that this stove just makes it as a rear venter.

 

[Highbeam]

My stove can be rear or top vented. I chose the top. How would this affect efficiency? The flue outlet on the rear vent allows the smoke more travel distance above the secondary baffle. Maybe the only difference is that the additional bend required to make the chimney vertical. So long as draft was adequate it would seem (a feeling) that the rear exit would be more efficient since the top vent allows the hottest smoke to escape.

 

[Corey]

I wonder if they may be figuring in the heat from the extra length of pipe that may be exposed if you do a top vent, whereas the rear vent, they may be expecting you to run directly into a chimney or through a wall?

 

[KeithO]

European stove. European homes are typically brick & mortar and non combustible. Thus if you go out the back, you loose the heat that would ordinarily be gained in radiation off the stovepipe. I can believe it makes that much difference on a small heater. It sounds like a more honest performance appraisal than most.