Rear flue exit VS Top flue exit

All things being equal is a wood stove installed with a rear flue exit any less efficient or inferior in any way to the same wood stove installed with a top flue exit ?

I have a fireplace insert (see my avatar) which I'm considering replacing with a wood stove and of course I would need to have a rear flue exit to make it work without modifying my chimney. To me the rear exit is not the preferred way. The top exit seems way more practical and efficient but I really don't know.

The stove I was thinking of getting is the jotul F3 CB which has both rear and top exit options and seems just large enough to heat my 1250 sq ft main floor. I was thinking of moving my insert to the basement and using it down there to heat that area up. Or maybe I should get a bigger wood stove and install it in the basement and heat the whole place up with it? Not sure.

Any ideas ?

fox9988 said:

https://www.hearth.com/talk/threads/another-woodstock-keystone-install.66069/#post-849450

Post #24

If rear vent was my only option, I would do it without reserve. But, I think top vent will draft better and you get a few BTU's off the connector pipe. Many say heat with your stove and not your pipe. If I'm blowing unnecessary BTU's up the chimney, I want them back. If that means sweeping the chimney more often, so be it.

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"...heat with stove and not your pipe..." ... how does one control that I wonder ?

Aside from that do you think replacing my fireplace insert with a good quality wood stove is worth the effort and expense ? Will I get more heat or is going up the chimney too ?

My dad has a wood stove in the basement in his rec room and it seems to throw way more heat than my insert, mind you it's a smaller area than my upstairs open area. I do have a blower on my insert but you stand about 8ft away and you can hardly feel the heat even though I have it as hot as I can get it (can hear the steel box clank sometimes). My dad can throw a few sticks in his stove and in minutes it's to hot to be in the rec room it seems... and there's no blower on it. It's like my insert gets hot but that heat is likely going up the chimney ? Hard to know sometimes. I'm going to call in some local experts but I'd like to get educated on wood burning and available options somewhat first.

mellow said:

I would recommend a rear vent freestanding over an insert any day if you have the clearance to combustibles and the hearth area to support it. It will heat better (due to not being IN the fireplace) and does not require a blower.

An insert to me is a last resort heating device, you have the fireplace but don't have the room for a freestanding then an insert will have to work.

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Good point. Maybe that's why someone put it in, found out not enough clearance for regular wood stove. I just assumed there would be enough clearance since there is a fire place there. I'll have to measure it out. Thanks for the tip.

Nick Mystic said:

When I went from an insert to a Jotul F 600 freestanding stove I had to use the rear vent set up to get inside my fireplace to a T-connector and then straight up my chimney. I don't have any problems with getting a good draft and I think the T-connector adds an extra layer of protection from creosote sloughing off the flue liner and clogging or impeding the smoke as it exits the stove. Anything coming down the flue ends up in the bottom of the T-connector several inches below the connection to the flue collar. Since the stove is designed to use either a top or rear connection I believe the manufacturer factors both methods of hooking up a flue to the stove to assure it will perform properly.

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That's good news I was thinking of using a T connector as well. I wonder if a person could get a T connector so the "bottom" of the T opens for easier clean out. I guess to clean out an installation as the one you have I'm assuming you have to disconnect and move the stove out from the fireplace ? The F-600 is almost 200lbs heavier than the F3 CB model.

Charles1981 said:

I have my stove setup rear vent. There is almost 4 feet of horizontal run before it hits the clean out T and goes up 26 feet.

Wouldn't have it any other way.

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4ft horizontal run seems very long. I wonder if there's any set limits on how much a person can run it horizontally. It's definitely good news for me though. I don't think I'll need to run it more than a foot or two I'm guessing.

firefighterjake said:

Probably depends some on the stove . . . if the F3 is anything like the F500 the rear exit and top exit are not all that drastic when it comes to changing the air flow/draft . . . I would guess we're talking inches since the part fits in the same place. If I had my druthers I would go with top exit, but I honestly don't think in most cases it would make much of a difference in terms of draft and stove performance . . . more of an issue if fitting it into an alcove or a particular set up.

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I would go top exit too but in my case it's so much easier to use a rear flue exit as there would be significant work for me to modify the existing fireplace to acommadate top flue exit. If there's no appreciable difference in efficiency and safety then I think I'm good to go from at least choosing between rear or top flue exit goes.

Thanks for the insight.

weatherguy said:

I'm going to do the same thing next year, replace my insert with a free stander, just need to build out my hearth 6 inches. Your father probably has a radiant stove while your insert is convective so you're going to feel the heat more with a radiant stove. As long as you size it right you should be fine.

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I'm doing ok with my insert, no complaints sort of, but can't help thinking I'm losing a lot of heat compared to a free standing stove. My dad has the jotul F3 CB free standing wood stove, it's almost 30 yrs old I think... I'll correct this if it's not the case. It cranks out the heat but hard to compare with mine as his area to heat is smaller than the area I'm trying to heat. My insert will take an hour to increase the temp by one deg 25 ft from the insert ( roughly middle of the house ). When it's really cold out (-20 or so) it's basically burn wood to keep the central heat from coming on, house is under 65deg so it's still a bit chilly.I'd have to burn real aggressive to heat the house from 65 to 70 and it would take hours. To me that just doesn't seam right.

Good luck with your insert replacement. I'm intending to replace mine in the summer if all goes well and I can afford it.

weatherguy said:

Are you considering a Jotul Frank? They have a couple stoves I really like but I also love the Progress Hybrid

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I am considering a Jotul. They seem to have the experience on their side and proven products, the Jotul F3 CB as one example which I've seen working many times over the years. I haven't heard of the Progress Hybrid but it sounds interesting and I'll google it to learn more.

fox9988 said:

Double wall pipe usually. It keeps the heat in the chimney, helps to prevent creosote condensation. I have 8 ft of single wall pipe + 8 ft of class A. Surface temp is usually ~125F at the ceiling. I like the extra BTU's. I will and do sweep as needed so it's not a hazard/problem for me. Each to his own.

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I just learned about the double wall pipe yesterday. It makes sense. Keeps the gases hot so they can escape and not condense due to huge temp diff between pipe and room? The rapid cooling of the single pipe can cause rusting I've heard, unless of course you use SS all the way. If I rear vent my stove (which I likely will) I won't have any stove pipe so I'll lose those BTU's.

Nick Mystic said:

With my Jotul F 600 I don't have much room to get behind it to remove the bottom cap on the T-connector for cleaning. However, there is a big top plate on the F 600 that is attached with just two bolts. Once that is removed you have ready access to the top of the baffle for inspection and cleaning and it's an easy reach into the T-connector for scooping out any creosote/ash that drops down from a sweep.

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That sounds good. I'd love to see what all that looks like. I didn't realize the T connector comes with a cap... but then that does make sense. I'd love to be able to have a set up where by I can reach in and remove that cap without moving the stove, and also be able to slide some kind of container in to catch the debris that falls down the pipe when cleaning. The jotul 600 is way to big for my application but maybe not if I burn softwood during the cold days. I read here somewhere it maybe advantageous to have a bigger stove because then you have the option of building both small and large fires.

begreen said:

It is. One needs a good uphill pitch on the horiz. section from the stove to the chimney and good draft to support this.

Some stoves are fussier than others about rear venting. The Castine for example is a shallow stove with a big door. In milder weather (above 45F) we would get a bit of smoke spillage when opening the door carefully. We were warned about this when the stove was installed with rear vent instead of top vent. I never hooked it up top vent but suspect it would have fixed this minor issue. This was with a 20ft tall flue system.

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I get some smoke spillage as well, not so much right now as it's -19 outside. So that spillage is likely from my insert having what I think is a rear exit flue? I'll know more this summer when I clean it out for the first time and if lucky sell it and replace it with a free standing stove. I have not used the stove since I got the SS liner installed many years ago. I disabled the insert that whole time as I rented my house out while I was away. It's likely due for a cleaning.