Venting questions

[scotthershall]

Hello everyone,

Well I’m a proud new owner of an ESW 25-PDV from AMFM. The purchase/home delivery process went flawlessly. I just need to do a dry run when I get a little time. The stove will be installed over the summer, which is what I have a few questions about.

The PDV will be replacing a wood stove which has an 8” stove pipe leading to a 25’ or so brick chimney with an 11” x 7” (approx) terra cotta flue. This is obviously way to large for a pellet stove.

The first option would be to install a 4” insulated liner. I’ve still got to decide if that’s a job I can do myself or if it’s worth paying someone to do. After watching plenty of Youtube videos, the process seems straightforward enough but being on a roof wielding a 25’ long piece of pipe wouldn’t be my favorite DIY activity... Looks like materials will be in the $650 range. Does anyone have any idea what it would cost to have a mason or chimney sweep do the job?

A second, and perhaps crazy, idea of mine would be to direct vent that thing straight through the hearth/chimney/clean out area to the outdoors behind the stove. This would require putting two holes in the brick and running vent pipe through. To me, there seems to be two benefits to this idea: 1) I can do it myself over the summer with masonry drill bits and chisels, and 2) it would make cleaning the vent pipe a heck of a lot easier or even possible depending on the weather. Given all the snow and cold temps we’ve seen in the past month and a half, cleaning the liner from the roof would be impossible, which to me would present serious concerns. I plan on using the pellet stove as primary heat with our electric baseboards as back up, so I could see me burning 3-4 tons per season, so per-ton clean will be important if only for peace of mind. I believe I could accomplish this without hitting the 4’ horizontal limit on venting, but I’m not sure how much vertical I’d need to compensate. There is a small clean out right near where I’d have the vent run through so I’d be able see what I’m planning on doing.

If I had to reverse the second idea, I’d just install a clean out door to make it look pretty outside or find matching bricks. If I were to switch to wood, I’d have to install a 6” liner anyway, and the holes I’d be adding for the pellet stove are a good 5’ below the thimble for the current stove pipe.

Anyway, what do you guys think?

Any info is greatly appreciated.

Thanks,

Scott

 

[Ranger72]

The stainless liners are extremely light weight. I'd run the 4" inside the existing liner. Just make sure you cap it off with a cap designed for a 4" liner.

 

[fmsm]

You can attach the 4" pipe to the cap with a simple worm clamp. A "t" on the bottom would allow you to clean from the bottom up.

 

[alternativeheat]

Run 4" flex, very light and you can uncoil it as you go. In fact I ran mine from the bottom up through my fireplace.. You shouldn't need insulated pipe. I think you would be the only person on the forum with one if you do that !! lol.

 

[scotthershall]

Run 4" flex, very light and you can uncoil it as you go. In fact I ran mine from the bottom up through my fireplace.. You shouldn't need insulated pipe. I think you would be the only person on the forum with one if you do that !! lol.

I thought the prevailing thinking on the forums here was to use an insulated liner to keep condensation/creosote/etc to an absolute minimum? Maybe I'm incorrect. My chimney is on the outside of the house, not an interior one. If I don't go with insulation, that knocks about $250 off the cost and will probably make it a somewhat easier to install, which would be nice.

 

[scotthershall]

You can attach the 4" pipe to the cap with a simple worm clamp. A "t" on the bottom would allow you to clean from the bottom up.

I thought of doing the cleaning from the inside... but I'm concerned with brushes/rods being able to make the 90 degree turn. I wouldn't be able to access the bottom of the tee to go straight up. I've got to pull the old wood stove out to take a look, but the last time I saw it, the thimble looked to be a good 10-12 inches long. So the brush/rods would have to go in 10 inches then make a 90 then go up 20-25 feet to the top. Do you folks think a Soot Eater, or similar system, could do that?

This brings up another question... I might have enough room in the chimney to make that 90 degree into the existing thimble with the liner itself rather than using a tee with the removable snout. It would possibly make cleaning easier since I could hold onto the liner while working the brush/rod through the turn and up the chimney. Since I can't access it, a clean out tee would pretty much be useless anyway. Is doing that with the liner permissible?

 

[scotthershall]

We do this all the time. Far better than going up the chimney. Makes it super easy to keep the flue clean. I recommend this to all customers as the first option.
Not crazy at all. You are thinking on your feet. Well done buddy.

At least I'm not crazy! Thanks for that info. Now, do you run a vertical length once outside the chimney to encourage draft, or just terminate it assuming the proper clearances are there? I'd rather just terminate it for cleaner look but it would be nice to have a little draft in case of a power outage.

 

[SidecarFlip]

I'm with Chickenman and suggested just that to another poster. Get your SDS drill out and some impact chisels and go straight through. Mortar up the voids and call it good. On the backside of the chimney you can put on a vent hood and call it good. You won't have natural draft but 3" pellet venting really don't make much natural draft in the first place..

and.........

It will be oh so easy to keep clean.

 

[johninwi]

I thought of doing the cleaning from the inside... but I'm concerned with brushes/rods being able to make the 90 degree turn. I wouldn't be able to access the bottom of the tee to go straight up. I've got to pull the old wood stove out to take a look, but the last time I saw it, the thimble looked to be a good 10-12 inches long. So the brush/rods would have to go in 10 inches then make a 90 then go up 20-25 feet to the top. Do you folks think a Soot Eater, or similar system, could do that?

Just use the flex rods and a fiber brush.
If your not going thru the back of the chimney like suggested by sidecar and chickenman, (they have far more experience than i) you won't have a problem getting a the flex rods and a brush around a 90, i go around 2 90's and up 20', they will fight you a bit when the screw joints are making the bend but it's not a big inconvience, just be certain to tighten the joints of the rods more than finger tight, or they just might come undone.
Also regulare inspection of the pipe will require being on the roof if that bothers you.
The out the back also make the pipe very inexpensive.
If you go straight out how far off the ground will the exhaust be? You mentioned an existing thimble, another option is into the thimble and thru the chimney to the outside if clearance above ground is needed, also gains you a bit of vertical to help with draft.

 

[scotthershall]

Hi everyone.

Took me a few days to get back to this... sorry about that.

Thanks for all the info. I'm happy to hear that the "out the back" method isn't crazy and is actually preferred in some cases.. I'll have to wait until all this snow melts (like, July sometime, maybe) so I can take measurements, get on the roof to evaluate the chimney, etc so I can decide what to do.

If you go straight out how far off the ground will the exhaust be? You mentioned an existing thimble, another option is into the thimble and thru the chimney to the outside if clearance above ground is needed, also gains you a bit of vertical to help with draft.

That's certainly another option. I think I'll have at least 12" of clearance from the ground, which I believe is what vent manufacturers require, but I need to do some measurements to be sure. Being that the current thimble is in the center of the hearth, going through it instead of making a hole specifically for the PDV (which has the exhaust located on the left side look at the stove from the front) might be better if we ever decide to change stoves. And with this setup I could use a traditional clean out tee behind the stove possibly making cleaning the vent pipe easier since I wouldn't have to move the stove. Hmmm... I'm starting to like this option...

Anyway, I'll report back when I can get some measurements and get on the roof.

Thanks everyone!

Scott

 

[scotthershall]

Well, I thought I'd report back and upload some photos so as to give some ideas to anyone searching for alternatives to lining their entire chimney...

Bought me a SDS rotary hammer from Harbor Freight for $69.99 with a coupon, and a set of 12" bits for $16. I figure buying one was better than renting one for $45/day. HF isn't best quality but it's not like I'm trying to make a living off of it... Anyway, the SDS drill went right though the chimney and terracotta liner. I drilled a series of holes in about a 5" circle then used a 3/4" cold chisel and 3lb hammer to remove the rest of the material.

I ended up buying the "out and up" Duravent kit from Lowe's for $229.99 but using it in an "up and out" configuration. I also bought a 12" adjustable pipe length that was placed right below the 90 degree elbow. I bought a 36" vent pipe as well and used that to go through the thimble and chimney to the outside. I ended up with two extra 12" vent pipe sections from the kit but discovered they were labeled for individual sale so I returned these to Lowe's getting about $30 back! I'll eventually paint the inside pipe using some high-temp paint. I've got two rolls of clear Nashua brand silicone sealing tape that I'll use to seal 'er up after that. If you notice the vent pipe is at an angle since the thimble and the stove exhaust didn't line up. I think a 45 elbow right at the appliance adapter will mostly straighten the vent pipe, but I think that's more cosmetic than anything so I'll do it if the wife gets on me about it.

The vent ended up with about 5.5' of clearance to the ground. I routed the OAK through the chimney clean out that lined up almost directly with the outside air inlet on the stove. At 20" off the ground it's a little lower than I'd like on the outside. I'll need to keep an eye on it when we get any significant snow on the ground. To mount it higher I would have needed to drill a hole in the chimney from the inside as well and I didn't want to do that but I think this will work fine.

The last pic is of one of my cats enjoying the heat from the old VC Vigilant that the pellet stove replaced. I should have taken a better pic before I removed the stove. Oh well. The VC was there when we moved in. It put out plenty of heat but the fire back was warped preventing the damper from closing, so it burned pretty inefficiently. I also don't have nearly enough room to season three winter's worth of wood. It was fun lighting up and filling the street with smoke; I think the neighbors will appreciate it being gone. And my wife will enjoy getting some heat at the push of a button... like when it's 55 outside and couldn't get a proper draft going with the VC...

Anyway, I hope this can be a resource to someone else.

Take care,

Scott

 

[scotthershall]

Well, I took this cool fall morning as an opportunity to start up the stove. Aaaaannnnd, smelled and saw smoke. I couldn't find where the leak was coming from but I saw wisps near the stove adapter. I assumed I somehow botched the seal job on the stove adapter, so I dragged the stove out, tore that apart and re-did it. I added a second screw on the other side of the first one to fully secure it (had some movement that I thought may have broken the silicone seal although the adapter was quite difficult to pull off the stove...). Put it back together, aaannnd still smoke.

I noticed it was just pouring out of the joints on the tee. It has silicone on the inside but clear it's just there for looks... Did some searching on here and found it was suggested to run a bead of hi-temp silicone around the exterior of all the joints. So much for my somewhat nice spray paint job...

I'm guessing that's not enough silicone tape between the tee and the adapter, so I'll add more once I verify the tee isn't leaking anymore. I've already wasted quite a bit of tape this morning...



Waiting for the silicone to dry. We'll see what happens then...

Scott

 

[scotthershall]

So that bead of silicone solved the leaking around the tee. But wait, there's more... leaks!

I had to seal up the tee cleanout cap which stopped the slow seeping of smoke from the bottom of the cap:


On the adjustable pipe piece I found the seam below the end of the pipe was leaking pretty badly, so some silicone tape solved that for now (it's the lower piece of tape in the picture):


The 90 degree elbow is also leaking in a few spots. That horizontal seam was leaking badly. I'm still getting wisps of smoke from around the entire seam that I started to seal, and the seam below that one (bottom of the pic).


I've been running the stove on 9-9 for about 2 hours now. I'm waiting to see if the elbow stops smoking. I see a lot of what appears to be oils from the manufacturing process seeping out. The darker section around the rivet in the above pic is oily residue. Just maybe it's that oil burning off ever so slowly... If not, I'll hit it with the silicone tape...

Of course, I realize now that I should have went out and bought some black hi-temp RTV instead of using the Permatex Ultra Copper I had in my tool box. But even the black stuff would have looked awful, but maybe slightly less awful. Hopefully this stuff is paintable...

I understand now why people drop some serious $$ on the Selkirk Direct Temp venting. Maybe in a few years...

Other than the leaks, the stove seems to be working great! Putting out some nice heat!