35' Pellet Vent in Chimney - Any problems?

[scelder]

I'm looking at a DIY pellet stove installation in an 1830 solid brick home. My two options (as I understand them) are:

1. Drill a +/- 4" hole (depending on brand) through 13-14 inches of solid brick masonry for a direct vent, cost of materials $200-400 depending on stove, etc., plus cost of masonry drill bit & damage to home

2. Run a 4" flex pipe up my 35' masonry chimney and finish off the top with a cap & rain guard. I recently had an insulated liner put in another chimney, and it ran for 35. Cost of materials $400-500, and the terror of getting up on my roof. Chimney has 2 slight bends on the way up (nothing extreme), hence the flex pipe.

At this point I'm not interested in wrecking my wall. Additionally, I'm probably going to go with a basic Englander or Pleasant Hearth, which would mean an L-pipe and riser up the exterior of the wall (correct? as opposed to more expensive Harmans, which have the more discrete power-venting option?), which would really wreck the look of my historic home. The double-walled insulated 6" pipe that I had installed for the woodburner was a real bear to get down the chimney, but i would think a single-walled 4" (especially if uninsulated) would be pretty easy for a couple of guys to drop down the chimney.

My question for for the 35' chimney is: Will this long of a run cause me any drafting or operating problems with the stove? I know pellet venting works somewhat differently than a woodburner (damned computers). The manuals I've read online mostly say "Over 15' of chimney, make sure you go with 4" pipe" -- but nothing about insulation (is it needed?) or if there is a max chimney height before problems start to emerge.

Any help would be appreciated - and if I'm mistaken on any points, please correct

 

[alternativeheat]

I had questions with my dealer on running 26' up my chimney uninsulated. He said nope just run 4". He said they run 35 ft all day long, 4". His words not mine. I have had 0 issues with mine. I ran mine from the bottom up and did all the bottom insulating and install on a Sat afternoon and fired it up that night. When my stepson could get over here about Thurs with a 40 ft ladder he did the topper for me. It all passed insurance inspection. All they wanted was the chimney re pointed but that was just in general, not because of the install.

 

[Golfeur]

Hello, I installed a Harman P68 basement to replace wood stove I used my fireplace 6 '' insulated 34 'I stove outlet with a T 3' 'right 40' 'right elbow 18' 'adapter 3 '' to 6 ''
I have no problem and when there is a hydro fault I did not smoke in the house

 

[alternativeheat]

Hello, I installed a Harman P68 basement to replace wood stove I used my fireplace 6 '' insulated 34 'I stove outlet with a T 3' 'right 40' 'right elbow 18' 'adapter 3 '' to 6 ''
I have no problem and when there is a hydro fault I did not smoke in the house

Same here, in fact if there was a way to feed the stove it might keep burning with no power !! Certainly no smoke for sure.

 

[scelder]

Thanks for the responses - good to know this would work!

 

[alternativeheat]

Thanks for the responses - good to know this would work!

On a 35 ft run I would suggest the smooth inside 4" flex though. Someone else could probably explain that better than me as to brand or model.. Basically it comes like you see the outside of a flex, with that rough interior. Or with a smooth interior. I just used plain old Duravent I guess and paid too much for it at the dealer. Could have gotten it online but I wanted to be able to go back if something went sideways on me and say, hey this doesn't work !! Sometimes its worth paying a little extra to deal with a local guy, sometimes it's not..

 

[batchman]

Adding to the experience base, I replaced a basement woodstove (that wouldn't draft) with a large pellet stove that requires a 4" vent. I ran 12" back, "T", 4' diagonal, "90" then 2' of flex into the existing 35' tall 6" masonry lined chimney (pointing up). My only problems were access to the horizontal flex for cleaning, and the stove prefers not to run below medium.

This year I changed the 90 to another "T", much easier for per-ton cleaning, too soon to tell what my chimneysweep will say. I will say cleaning the "corrugated" flex pipe is not ideal as the pleats trap ash.

I think you'd be fine, especially if you can use smooth sided pipe. The question will probably be how low can you run the stove, I can't use the hi/lo thermostat mode with my setup but that's OK by me.

So, as far as making holes in your house, save it for the outside air kit - which as someone who lived in an antique a long time I suspect you will want really badly.

Cheers,
- Jeff

 

[scelder]

Adding to the experience base, I replaced a basement woodstove (that wouldn't draft) with a large pellet stove that requires a 4" vent. I ran 12" back, "T", 4' diagonal, "90" then 2' of flex into the existing 35' tall 6" masonry lined chimney (pointing up). My only problems were access to the horizontal flex for cleaning, and the stove prefers not to run below medium.

This year I changed the 90 to another "T", much easier for per-ton cleaning, too soon to tell what my chimneysweep will say. I will say cleaning the "corrugated" flex pipe is not ideal as the pleats trap ash.

I think you'd be fine, especially if you can use smooth sided pipe. The question will probably be how low can you run the stove, I can't use the hi/lo thermostat mode with my setup but that's OK by me.

So, as far as making holes in your house, save it for the outside air kit - which as someone who lived in an antique a long time I suspect you will want really badly.

Cheers,
- Jeff

The OAK (from what I understand) does not need to have a vertical rise, and for most applications can make a pretty long run -- the hope there would be to put a small hole through the wood floor and run it out through the nearby basement window.

I think if I can swing the expense of a Harman, I would put the hole through the wall for their power vent system, which I believe integrates exhaust and OAK.

 

[Pete Zahria]

So exactly what does just running your pellet stove into an existing chimney do
to adversely effect the stove's operation?
Just curious.

 

[scelder]

So exactly what does just running your pellet stove into an existing chimney do
to adversely effect the stove's operation?
Just curious.

Not an expert (I'm the one asking the questions!) but if you were to just vent a short pipe (i.e., not the entire length of the chimney) into the flue, you would have all sorts of downdraft issues, problems creating draw, and the danger of your exhaust gasses being forced back into your living space -- not to mention sparks and embers during a malfunction falling back on your stove or hearth.

It's just generally dangerous, inefficient, and ineffective because the stoves are manufactured to be sized to a certain flue which creates a certain draw, etc. etc. . . .

 

[Pete Zahria]

I'm confused.
Looking at the Harman instruction sheet, one of the venting options is to run it
into an existing chimney, providing it has a good clay liner..
My coal stove has very little air flow going through it, and no blowers.
It maintains a ~.08 draft all the time. the temp on the pipe by the thimble
is usually around 175-185°, which is cooler than my shop pellet stove..
(that one is direct vent..)
But I have toyed with a p68 to replace the coal stove. But won't consider it
if I have to fart around with the chimney...

Believe me, I am not trying to argue the point, I am just looking for the reasoning
for not running it into a clay lined chimney... if it shouldn't be done, then that is that....
I'll scrap the thought of the pellet stove.... thanks..

(broken image removed)

 

[scelder]

I'm confused.
Looking at the Harman instruction sheet, one of the venting options is to run it
into an existing chimney, providing it has a good clay liner..
My coal stove has very little air flow going through it, and no blowers.
It maintains a ~.08 draft all the time. the temp on the pipe by the thimble
is usually around 175-185°, which is cooler than my shop pellet stove..
(that one is direct vent..)
But I have toyed with a p68 to replace the coal stove. But won't consider it
if I have to fart around with the chimney...

Believe me, I am not trying to argue the point, I am just looking for the reasoning
for not running it into a clay lined chimney... if it shouldn't be done, then that is that....
I'll scrap the thought of the pellet stove.... thanks..

(broken image removed)

Looks like a tight clay liner in good condition would be fine, but it's still technically a liner (as opposed to a masonry stove that is just brick or stone). Also, if you'll notice in that particular picture they are also showing a 3'+ rise off the back of the stove to a thimble into the chimney. If there was no chimney and that thimble just went through the wall to the outside, that would be an acceptable installation.

Ash, etc. can still be cleaned out of the bottom of the chimney, and would not fall back on the stove or into the living area. Additionally that vertical rise inside the house helps create enough draft to counteract any downward pressure in the chimney itself. And downward pressure in the chimney wouldn't push gasses back into the house.

To your initial question, it seems like when most people ask the question about sticking a pellet stove in a chimney, they are thinking of pushing an insert or upright unit into their open-hearth fireplace and running 2' or 3' short feet of pipe straight up into the open chimney to stave money.

 

[alternativeheat]

I'm confused.
Looking at the Harman instruction sheet, one of the venting options is to run it
into an existing chimney, providing it has a good clay liner..
My coal stove has very little air flow going through it, and no blowers.
It maintains a ~.08 draft all the time. the temp on the pipe by the thimble
is usually around 175-185°, which is cooler than my shop pellet stove..
(that one is direct vent..)
But I have toyed with a p68 to replace the coal stove. But won't consider it
if I have to fart around with the chimney...

Believe me, I am not trying to argue the point, I am just looking for the reasoning
for not running it into a clay lined chimney... if it shouldn't be done, then that is that....
I'll scrap the thought of the pellet stove.... thanks..

(broken image removed)

Yes this is a Harman option, as is going into a lined chimney through an existing fireplace. In that diagram ( the latter) they show about 6 ft of flex into a clay liner up from the fireplace with a bottom block off place ( obvious pain to clean though). Nothing is falling into the living space but onto the old smoke shelf and bottom cap or block off plate if you will. But that's Harman, not all manufacturers show the same diagrams and some show a pellet sized metal liner through existing clay lined chimneys..

If your install is like your diagram you put up and you have a bottom clean out, then it looks blessed by Harman to me and with clean out capability. There is no way to compare coal stove draft with pellet stove positive pressure except to say just that. Coal stoves generally use draft or draw from heated gasses rising up the chimney. Pellets stoves use positive pressure in the exhaust but obviously Harmam isn't too concerned with that part once past the limited rise required in their diagrams.

 

[Pellet-King]

My Insert I use 3" of SS Flex 20' up to top of chimney, I know i should of used 4" but what is done is done and havent had any issue's except one time I was burning on low for long periods and eventually my pipe got clogged with creosote, quick blast from leaf blower cleaned it out.
Other house stove was in I just had a blockoff plate and 6' of 3" SS pipe, problem is the ash build up on top of the plate and was a mess once removed after10 yrs of use

 

[MarkF48]

I've been operating a Harman XXV into a clay lined chimney as shown in the diagram above since 2011. Stove has been operating fine. The exhaust vent pipe has about a 4' rise to the chimney thimble. This method applies to the Harman XXV, but I don't know if for other models or manufacturers this would be acceptable.
I did put a cap over the top of the chimney as for some reason ducks seem to have had a propensity for falling into the chimney.

 

[Pete Zahria]

..for some reason ducks seem to have had a propensity for falling into the chimney.

I found one in my cleanout once, when I tell people that they think it's a yarn.....
Sad part was, she laid an egg before she died..

 

[Pete Zahria]

... Coal stoves generally use draft or draw from heated gasses rising up the chimney. Pellets stoves use positive pressure in the exhaust but obviously Harmam isn't too concerned

And once the heated gas from your pellet stove is introduced into the masonry chimney, those gases will rise..