What kind of pipe do I need to go up through chimney?

[scott walter]

Hi, this is my first post....the guys at woodnet.net suggested I ask my question here since it is about a stove. I have a Baby Bear type little freestanding stove. I also have a heartch with a functioning fireplace. I was considering two types of installs. 1. I was going to place the stove on a pad (2x2 frame with plywood, backerboard and ceramic tile) directly in front of the hearth with a pipe exiting the back of the stove and entering the firebox. I was going to have a sheet of metal closing off the firebox so the pipe would go throught the sheet material with an elbow pointing the smoke and let the chimney draw. 2. It was suggested by some on the other site that I run the pipe all the way up the chimney and insulate around the pipe. If so, do I need inuslated pipe? or fireproof insulation around the pipe? Also, the previous owner took the damper from the chimney, so I have a rectangular hole there. If the pipe should go up past that, is it ok to extend the pipe through the rectangular hole and reshape to my needs?

The factors for decision making are obviously safety. Both short term and long term. Second is cost. I already have the stove and the sheet metal was free.

I appreciate any help. I have made about 6 calls in 2 days to the county/city and I can't get anyone to answer my calls.

 

[Woody Stover]

directly in front of the hearth with a pipe exiting the back of the stove and entering the firebox. I was going to have a sheet of metal closing off the firebox so the pipe would go throught the sheet material with an elbow pointing the smoke and let the chimney draw.

Some klown installed my wife's first stove here like that. Volatile gasses built up in the fireplace and smoke chamber. She opened the door, supplying more oxygen, and the whole mess exploded, ripping the door out of her hand, knocking her on her butt, and filling the entire room with thick smoke. So I suggest that you do something else. At least "direct connect" up to the clay liner tile. If your tile liner isn't too huge, that might work OK.

"Positive" connection is the best. But a stainless chimney pipe to the top ain't cheep...

Positive, Direct, Slammer.

 

[chimneylinerjames]

You need to install a stainless steel chimney liner from the stove to the top of the chimney. Use insulation. Some people will say just do the top and bottom, but to maintain the UL listing you need to insulate the chimney liner the entire length.

Use the same size liner as the flue outlet on the stove.

 

[scott walter]

You need to install a stainless steel chimney liner from the stove to the top of the chimney. Use insulation. Some people will say just do the top and bottom, but to maintain the UL listing you need to insulate the chimney liner the entire length.

Use the same size liner as the flue outlet on the stove.

Why do I need insulation? The surrounding clay flu is in place and it currently takes a fire now. I just talked to a guy that installs stoves and he is telling me I don't have to do anything but run a pip about 5 feet up from the fire box with no insulation. I'd like to know the "why's"...not just the "what's".

thanks for the help by the way.

 

[chimneylinerjames]

For a few reasons. One is obviously safety. I understand it is ok to just have flues in the home and use a wood stove, but it is not me saying this but UL requires insulation on chimney liners that handle solid burning appliances like wood. So if you have a liner installed an say you have a chimney fire, if anything happens they are going to look at the chimney liner to see if it was installed according to the manufacturers instructions, (UL requirements).

Another reason is performance, read other threads on here about draft difference between an insulated liner and non-insulated liner, many people are mad they didn't insulate form the beginning and are impressed with the stoves performance with an insulated liner.

The problem with just adding 5' of liner is the that once the smoke enter into a chimney designed for an open fireplace, the smoke has too much, what is called residency time. That is time in the chimney. When it is in the chimney it has time to cool down which then creates creosote. It was explained to me like this one time. Think of venting a wood stove in the attic with a small hole in the roof on the opposite side of the room. Do not have anything attaching the stove to the hole, just the stove sitting on the floor venting out of the top and a hole in the roof. Will the smoke will vent out of the hole in the roof? Sure. But will it draft well? Nope. It is because you are venting it into an area much larger than the stove was designed to vent into. That is exaggerated but you get the idea.

Now take the same scenario and add a 6" round pipe directly from the stove to that hole. Now how will it draft? The answer is obvious.

That is my 2 cents. I never installed a liner for a wood stove that wasn't insulated all the way and never ever had a complaint about weak draft. I figure if you are going to do it, do it right the first time.

 

[scott walter]

For a few reasons. One is obviously safety. I understand it is ok to just have flues in the home and use a wood stove, but it is not me saying this but UL requires insulation on chimney liners that handle solid burning appliances like wood. So if you have a liner installed an say you have a chimney fire, if anything happens they are going to look at the chimney liner to see if it was installed according to the manufacturers instructions, (UL requirements).

Another reason is performance, read other threads on here about draft difference between an insulated liner and non-insulated liner, many people are mad they didn't insulate form the beginning and are impressed with the stoves performance with an insulated liner.

The problem with just adding 5' of liner is the that once the smoke enter into a chimney designed for an open fireplace, the smoke has too much, what is called residency time. That is time in the chimney. When it is in the chimney it has time to cool down which then creates creosote. It was explained to me like this one time. Think of venting a wood stove in the attic with a small hole in the roof on the opposite side of the room. Do not have anything attaching the stove to the hole, just the stove sitting on the floor venting out of the top and a hole in the roof. Will the smoke will vent out of the hole in the roof? Sure. But will it draft well? Nope. It is because you are venting it into an area much larger than the stove was designed to vent into. That is exaggerated but you get the idea.

Now take the same scenario and add a 6" round pipe directly from the stove to that hole. Now how will it draft? The answer is obvious.

That is my 2 cents. I never installed a wood stove that wasn't insulated all the way and never ever had a complaint about weak draft. I figure if you are going to do it, do it right the first time.

ChimneylinerJames....that is a nice answer. thanks. I will ask another extending off your response. Why is it safer to have insulated then not? I understand that you mentioned UL req's and chimney fires. How does an uninsulated pipe make it more dangerous? What is going to catch on fire? I can clean the pipe to prevent any buildup. Don't get me wrong, I am not being argumentative but I am conflicted. My last gas bill was unbearable and I have a free stove (my dad's), free blockoff plate, and free wood. I am basically unemployed...at best very underemployed so I am trying to understand why I need to pay the inflated price for SS insulated pipe vs the cheaper black pipe. Again, thanks for your help.

 

[begreen]

Black pipe is not an option. It is against code and plain bad economy, so let's talk about stainless uninsulated vs insulated liners. You might be able to stub it with a damper sealing block off plate but this could lead to a dirty, creosote accumulater. If your chimney is tile-lined and it's in great shape it might be ok with an uninsulated stainless liner. The issue and question here is about sustained heat. An uninsulated liner radiates a lot of heat. In the event of continued high temps in the liner, the adjacent chimney will also warm up, especially if the liner is touching the brick or tile liner as it often does. If the tile is flawed, cracked or if there is no tile liner, wood touching the chimney will also warm up. Long term exposure to heat reduces wood's combustion temperature significantly. Eventually wood can combust under these conditions.

Are you certain that the chimney at all points has at least a 1" air gap from any combustible? Does the chimney have a tile liner that is in excellent condition? If so, you will probably be safe with a stainless liner that is uninsulated. But we have not covered stove performance and creosote. The wood stove typically has a 6" or 8" flue collar. When the smoke from the stove is dumped into a cold chimney with say a 10" x 12" throat, the flue gases slow down a lot and they rapidly cool down. This is especially true if it's a cold exterior chimney. That leads to a lot of creosote condensing on the chimney walls. A liner will keep the flue gases moving faster and hotter and an insulated liner even better. So there is the added advantage of a cleaner flue and less risk of chimney fires.

 

[chimneylinerjames]

Black pipe is not an option. It is against code and plain bad economy, so let's talk about stainless uninsulated vs insulated liners. You might be able to stub it with a damper sealing block off plate but this could lead to a dirty, creosote accumulater. If your chimney is tile-lined and it's in great shape it might be ok with an uninsulated stainless liner. The issue and question here is about sustained heat. An uninsulated liner radiates a lot of heat. In the event of continued high temps in the liner, the adjacent chimney will also warm up, especially if the liner is touching the brick or tile liner as it often does. If the tile is flawed, cracked or if there is no tile liner, wood touching the chimney will also warm up. Long term exposure to heat reduces wood's combustion temperature significantly. Eventually wood can combust under these conditions.

Are you certain that the chimney at all points has at least a 1" air gap from any combustible? Does the chimney have a tile liner that is in excellent condition? If so, you will probably be safe with a stainless liner that is uninsulated. But we have not covered stove performance and creosote. The wood stove typically has a 6" or 8" flue collar. When the smoke from the stove is dumped into a cold chimney with say a 10" x 12" throat, the flue gases slow down a lot and they rapidly cool down. This is especially true if it's a cold exterior chimney. That leads to a lot of creosote condensing on the chimney walls. A liner will keep the flue gases moving faster and hotter and an insulated liner even better. So there is the added advantage of a cleaner flue and less risk of chimney fires.

Very well said.

 

[scott walter]

Very well said.

Ok, ya'll have convinced me. I will run SS insulated pipe to the top of my chimney. I assume it would have to start where the black pipe goes throught the sheet material and the elbow starts to go up. Would that be where the SS should start?
thanks again

 

[chimneylinerjames]

Does this stove vent out the rear, horizontally? If so, use a tee on the bottom of the liner. Then from the stove to the tee you could use the black pipe. If the stove will sit inside the fireplace and vent out of the top, use an appliance connector and run the liner directly to the top of the stove.

 

[scott walter]

Does this stove vent out the rear, horizontally? If so, use a tee on the bottom of the liner. Then from the stove to the tee you could use the black pipe. If the stove will sit inside the fireplace and vent out of the top, use an appliance connector and run the liner directly to the top of the stove.

yeah, the stove has the hole in the back. I was looking online and the flexible SS pipe with the wrapped insulation looks pretty good and easy. The site I am on offers 25% off via sale right now. Any problems with the flex pipe?

thanks.

Just brought home 3 truckloads of Elm and gotta get at least that in the morning.

 

[chimneylinerjames]

There is no problem with the flex pipe at all. That will work great for you. Purchase a "tee kit", that will give you the 90* turn into the back of the stove and also a clean out on the bottom. Then from the tee you could use black stove pipe or purchase a little extra stainless and have all stainless pipe.

Take advantage of that sale!!

 

[scott walter]

There is no problem with the flex pipe at all. That will work great for you. Purchase a "tee kit", that will give you the 90* turn into the back of the stove and also a clean out on the bottom. Then from the tee you could use black stove pipe or purchase a little extra stainless and have all stainless pipe.

Take advantage of that sale!!

Wierd, I talked with my insurance agent today and there no requirements for SS, insulated, black pipe, or anything. Whatever used has to be UL listed and has to be done be a professional if not by the homeowner. Plus, the guy from the county finally called me back and he said there is not a code that covers me putting a stove in an existing fireplace. I was suprised at both.

 

[chimneylinerjames]

Plus, the guy from the county finally called me back and he said there is not a code that covers me putting a stove in an existing fireplace.

What do you mean? If you install a stove it is illegal? Not up to code?

 

[scott walter]

What do you mean? If you install a stove it is illegal? Not up to code?

No....what he actually said is that I have to do what I feel is safe. He couldn't advise me regarding coding req's. I was suprised.

 

[chimneylinerjames]

Let me tell you what is safest. Install a flex liner with insulation on the liner all the way to the top of the chimney, insulation and SS liner. Install a plate in the fireplace to stop the heat from going up the chimney.

 

[Kenzen]

I want to rekindle (pun intended) this thread because I'm asking the same questions for my own stove-into-the-fireplace installation. Specifically, the question is on the value of insulation around a full length liner. As I come to understand it, the insulation allows the liner to heat up quicker, and stay warm/hot since it's not losing heat to the cold brick. With a hot liner, the updraft is now more powerful since the exhaust gas stays warmer, and thus the performance or efficiency goes up. Also, the hotter exhaust fumes will reduce the depositing of creosote. Am I thinking correctly on this?
Thanks,
Ken

 

[begreen]

Yep.

 

[Kenzen]

Thanks!