Insert installation - stovepipe questions

[runswithsizzers]

My Englander 24-JC is presently installed in a masonry fireplace by the "direct dump" method. That is, flue gasses come out of the top of the stove and go directly up the chimney without any metal stove pipe; the only thing that seals off the chimney from the interior is fiberglass packed between the back of the cover plate and the front of the fireplace. The chimney is external, and lined with clay fireplace tiles or tubes which seem to be in good shape. The insert works OK now, except it's impossible to open the door without quite a bit of smoke getting into the room - and occasionally it back puffs with significant amount of smoke and noise.

I've heard this is a sub-standard installation method, so I'm considering adding some stove pipe. Why? I'm not sure - safety(?) improved draft(?)

1. Do I need to go all the way to the top of my chimney with the stove pipe, or is part way enough? How much is enough?

2. Is single wall OK, or should I use double wall? Regular steel, or stainless?

My situation is greatly complicated by some kind of heat exchange system - there are several large diameter metal pipes blocking the throat of the fireplace, which will have to be cut out with a saw or torch before any stove pipe can pass through. So, it's going to be a major project ...

3. ... is it worth the effort, or should I live with it, as is?

4. I'm a "Do It Yerselfer" - light electrical, plumbing, carpentry, automotive, etc. - but I'm wondering if this something I should leave to the pros?

5. I guess after more than 10 years of use, I should replace the ceramic catalytic combustor, too?

Thanks,
-gw

 

[begreen]

A full liner is the way to go. Cut the heat pipes that are in the way of the liner with a sawzall. If the combustor is still working and in decent shape, then no need to replace. If it's breaking down and performing poorly, then yes.

 

[Hogwildz]

My Englander 24-JC is presently installed in a masonry fireplace by the "direct dump" method. That is, flue gasses come out of the top of the stove and go directly up the chimney without any metal stove pipe; the only thing that seals off the chimney from the interior is fiberglass packed between the back of the cover plate and the front of the fireplace. The chimney is external, and lined with clay fireplace tiles or tubes which seem to be in good shape. The insert works OK now, except it's impossible to open the door without quite a bit of smoke getting into the room - and occasionally it back puffs with significant amount of smoke and noise.

I've heard this is a sub-standard installation method, so I'm considering adding some stove pipe. Why? I'm not sure - safety(?) improved draft(?)
Typically a "slammer" install takes piping to the first flue tile, above the smoke shelf or just to the old damper, and has a block off plate installed just below the damper.

1. Do I need to go all the way to the top of my chimney with the stove pipe, or is part way enough? How much is enough?
You don't want to use stove pipe, you want liner approved for the installation type. Yes go all the way, that way you don't have to remove the insert to clean the chimney each cleaning.

2. Is single wall OK, or should I use double wall? Regular steel, or stainless?
Use stainless steel approved flex or rigid. Can be insulated or not, insulated adds added safety, and may be needed to meet code, and usually helps draft, and should relieve your smoke back puffing.
I went double wall rigid with flex at the very bottom from first flue tile to the insert. The double wall is pre insulated.

My situation is greatly complicated by some kind of heat exchange system - there are several large diameter metal pipes blocking the throat of the fireplace, which will have to be cut out with a saw or torch before any stove pipe can pass through. So, it's going to be a major project ...
Cut them the hell out of the way. Just what you need to. Make sure they are not structural.

3. ... is it worth the effort, or should I live with it, as is?
I would NOT burn that way, is your life and your family worth it?

4. I'm a "Do It Yerselfer" - light electrical, plumbing, carpentry, automotive, etc. - but I'm wondering if this something I should leave to the pros?
Very capable DIY project, did mine and helped a few others, many here do their own. Do it right! Don't skimp.

5. I guess after more than 10 years of use, I should replace the ceramic catalytic combustor, too?
Take it out and inspect, prolly shot, but ya never know.

Thanks,
-gw

 

[runswithsizzers]

Hogwildz,

Thanks for your reply. Sorry about the newbie questions (and long post) - it is not my intention to be argumentative, but only to be sure I understand correctly before starting the project:

I don't know what you mean by <“slammer” install> but I'm guessing you do not approve of a partial lining?

If a "block-off plate" is needed for partial piping, does that mean a block-off plate is not needed for a fully lined installation?

When you say "insulated adds added safety" - what kind of safety? My liner will be inside of a massive exterior masonry chimney with a good clay tile liner. I don't believe there is any risk of the lining heating up the interior of the chimney any hotter than it's already been during it's 60 year life - so there would be no extra danger to my wood structure caused by the liner - with or without insulation - right?

You say: "I would NOT burn that way, is your life and your family worth it?" It's not obvious to me how my installation is life threatening - what, exactly, is the danger?

The Owner's Manual for my insert shows 2 methods for installation: "1. Direct Connect: ... requires 8" diameter 24 gauge pipe from the stove thorough the damper opening. ... necessary to block off the open area around the pipe ... with sheet metal..." and "2. Direct Dump" - which is my present installation, as previously described. In other words, if I've followed the manufacturer's directions for installation - can it really be that bad?

Finally, a new complication. The opening in the top of my insert is 8" in diameter - but the inside dimensions of the clay tile chimney liner is about 6.5-6.75" square. In other words, there is no way I would be able to use a liner larger than 6" in diameter, and there's probably no room for a 6" liner plus insulation. Is that enough square inches? My exhaust gasses go through a 6" diameter ceramic honeycomb catalytic combustor, so it can't really need the whole 8" diameter, but how much smaller than 8" can I go? If 6.5" square, my tile has a cross section of 42 sq inches - while a round 6" liner would be about 28 sq inches (a 33% reduction). Does that sound like enough? The stove doesn't draw great, now - several possible reasons for that - but I'd hate to spend a bundle on too-skinny pipe to make it worse.

-gw

 

[begreen]

The insert requires at least 50 sq in. of flue and is being choked down to about 42. The heat exchanger pipes are adding some amount of added resistance. Look in the manual for what it says about flue requirements. Add the slammer install (no stub above the damper and no block off plate) and you have at best a poor behaving system. At worst, under the right conditions, it could reverse draft and fill the house with smoke or CO.

Flue Size Needed:
The proper flue size is normally determined by the inside diameter of the opening on the unit, which in this case is eight inches (8”). Therefore, the connector pipe should be the same size or larger and never less in diameter than the opening on the stove. The area of the chimney liner in square inches must also be equal to or larger than the area of the opening on the stove.

 

[runswithsizzers]

BeGreen,

Thanks for your valuable suggestions.

Turns out I was wrong about my flue dimensions. There are 2 passages in my fireplace: one is 6.5"x6.5" for the furnace (inside dimensions) - I had a piece of that on the ground from an old repair, and that is what I measured for my initial post. I had forgotten that the second passage, the one which vents the fireplace is bigger - 6.5"x11" - giving me a little over 70 square inches.

I got no manual with my (used) insert purchase, but after downloading the manual from Englander's website, I read this:

"The proper flue size ... is 8". Therefore the the connector pipe should be the same size or larger and never less ..." Then the manual goes on to contradict itself: "Exception: If you reline the flue and direct connect this unit, a 6" flue liner is acceptable."

So it looks like a reline is doable in 6" - but probably no room for insulation.

Hmmm... The mfg says "acceptable" - not sure if that's a recommendation or a warning. Would it be preferable to go for an un-insulated 6" reline to the top - compared to running 8" through a block off plate and as far up as I can go - which won't be far once I get to the 6.5"x11" flue lining (might be able to ovalize it for a few inches). I haven't got the old heat exchange pipes out of the way yet, so I haven't got accurate measurements of the old damper throat area. Just to eyeball it, looks tight - I think 6" would go - 8" maybe not.

-gw

 

[begreen]

The large flue is certainly better. How tall is the chimney?

If you want to go insulated, Simpson Duraliner oval liner is insulated and designed for this type of installation.

 

[runswithsizzers]

The large flue is certainly better. How tall is the chimney?

If you want to go insulated, Simpson Duraliner oval liner is insulated and designed for this type of installation.

BeGreen - It's about 19 ft from the top of the insert to to the top of my chimney.

It's not that I WANT to go insulated - I'm just trying to improve my "slammer" install (your term, I don't even know what that means). My goal right now is only to provide a safe and functional install without going overboard on cost and complexity. If going through a stop plate with single wall pipe into my flue is adequate, then I'd be happy with that, for now.

The Simpson Duraliner oval liner looks great, but too costly for me to consider right now. In the future, I might want a full re-lining to simplify creosote removal - that is, if a full reline means I don't have to pull out the insert at cleaning time.

Thanks,
-gw

 

[webbie]

Given that flue tile size, your choices are limited somewhat without major work.......

Assuming that you feel the chimney is built safely as-is, the best draft may be gained by this method - use a 8 to 7 adapter (ss) and then use a 7" flex pipe up to as close as you can get to the first flue tile. Make up a metal block-off plate which fits as tightly as possible (we have an article here on how to do it)....

Looking at the specs on that insert, I'm not sure why they used an 8" flue. Based on the firebox size, a smaller flue would easily vent the products of combustion - my guess is that the particular design of the stove and loading door made a little smoke leak out when the door is opened, so they went with the larger 8" flue. That is a rarity these days - quite a few inserts and stoves with much larger fireboxes have smaller flues.

If you are going to do a complete reline, my suggestion is to use RIGID pipe, not flex. Flex has a large OD and also hinders draft a bit more. In this case, of course, you would have to step down to 6".

In the end you might have to add some height, which should not be hard if you reline it...and, in fact, there are ways of doing so even if you do not reline the chimney.

 

[runswithsizzers]

Assuming that you feel the chimney is built safely as-is, the best draft may be gained by this method - use a 8 to 7 adapter (ss) and then use a 7" flex pipe up to as close as you can get to the first flue tile. Make up a metal block-off plate which fits as tightly as possible (we have an article here on how to do it)....

Thanks - just the kind of specific advice I was looking for. I'm going to try to do it this way unless the local pros can talk me out of it with something both better and affordable. My stove opening is just about exactly 8" - can I expect the 8-to-7 inch adaptor to fit in my stove opening, or do I need something in-between?

Looking at the specs on that insert, I'm not sure why they used an 8" flue. Based on the firebox size, a smaller flue would easily vent the products of combustion - my guess is that the particular design of the stove and loading door made a little smoke leak out when the door is opened, so they went with the larger 8" flue. That is a rarity these days - quite a few inserts and stoves with much larger fireboxes have smaller flues.

You are right about the door design - only if done in slow motion can the door be opened without a puff of smoke in your face. I thought the 8" was oversize, too. With the top damper (bypass) open, the gasses can exit from a 3"x9" rectangle and a 5.5" circle which is mostly filled with ceramic - less than 51 sq.in, total. With the bypass closed, the total is reduced to less than 24 sq,in.

If you are going to do a complete reline, my suggestion is to use RIGID pipe, not flex. Flex has a large OD and also hinders draft a bit more. In this case, of course, you would have to step down to 6".

In the end you might have to add some height, which should not be hard if you reline it...and, in fact, there are ways of doing so even if you do not reline the chimney.

I've got a couple of "pros" coming to give me estimates - is there a rectangular or oval ridged material available that I should ask them about?

 

[Hogwildz]

What was not mentioned to you is if you do not reline all the way to the top of the old chimney, you will have to pull the insert out for each cleaning, ans the ash and crud will fall around the short stub of piping you run up to the first flue. Which is either going to be a pain in the ass for you to do each year while sweeping the chimney, or cost you a hell of alot more down the road in additional charges each time a sweep comes out and has to do it.
Or in some cases as was mine the first, last and only time I hired a sweep, he left it in and swept the crap down leaving what fell sound the outside of the stub laying there. Of course I found it, it found me, and I cleaned and wore alot of it when I pulled that old insert out and installed the new one and new liner myself. Now I pull the baffle, sweep the liner, reinstall the baffle and go for the season. I even leave the crud I swept down in there until the first scooping of ash is needed. Just my two cents. Sometimes short term savings are not in the long run.

 

[runswithsizzers]

... if you do not reline all the way to the top of the old chimney, you will have to pull the insert out for each cleaning, ans the ash and crud will fall around the short stub of piping you run up to the first flue. Which is either going to be a pain in the ass for you to do each year while sweeping the chimney, or cost you a hell of alot more down the road in additional charges each time a sweep comes ...

You are right about that! We have been pulling the insert out each year for cleaning, and it's a major ordeal without the added complexity of a block-off plate and partial pipe.

I just found out about the 30% tax credit for buying a new high efficiency "biomass" stove. Looks like the credit will apply to the lining and labor, too (with the new stove purchase)! So, for not much more than the $1900 the pros want to reline my chimney for use with my old insert, I can get a new insert AND the SS lining! That decides it for me - I'm shopping for a new insert.

Anybody want to buy a used Englander 24-JC with a brand new catalytic ceramic combustor?