Chimney Liner Installation Details

[patrickoneal]

I'm getting a wood burning insert for my fireplace. From the reading I have done, it seems the best practice is to install an insulated liner. I poked my head in the fire place and opened the damper. The flue tile looks to be either 12x12 or 13x13, so there is plenty of room:



I understand the details about building a block off plate, and insulating it with roxul. My questions concern the top of the chimney. My chimney has two flues, one of which is used by a high mass natural gas boiler in the garage. There is one large rain cap covering both flues. Here is a picture from bing maps, as it's too dark to take a photo at the moment:



Can I just terminate my flexible liner into a top plate and reinstall the large common rain cap? I assume the top plates include a hose clamp or some other means of holding the flexible liner? Being that I'm planning to reuse the existing rain cap, I figured on just getting a flat top plate and attaching it with silicone to the flue since I'm not certain of the flue tile size:


Should I just cut the top of the liner flush with the collar or leave it proud a few inches?

Being that there are two flues: Will I likely encounter smoke traveling back down the gas boiler flue? The boiler does have a motorized damper, but it will run when the stove is in use because it also produces DHW.

And finally: Can anyone recommend a supplier for a preinsulated stainless flexible liner for a good price?

 

[bholler]

Can I just terminate my flexible liner into a top plate and reinstall the large common rain cap? I assume the top plates include a hose clamp or some other means of holding the flexible liner? Being that I'm planning to reuse the existing rain cap, I figured on just getting a flat top plate and attaching it with silicone to the flue since I'm not certain of the flue tile size:

Yes that is fine

Should I just cut the top of the liner flush with the collar or leave it proud a few inches?

Yes cut it flush

Being that there are two flues: Will I likely encounter smoke traveling back down the gas boiler flue? The boiler does have a motorized damper, but it will run when the stove is in use because it also produces DHW.

It can happen but will not when the boiler is running for sure. And while it can happen it is not that common. If it turns out to be an issue you will have to extend one of them but I would not do that without knowing if there is an issue.

 

[patrickoneal]

Excellent. Thank you for the advice.

And for the last question, does anyone know the best place to order an insulated liner for a good price?

 

[Xtrl9]

Do you want to order an insulated liner for a good price or order a nicer quality liner and insulate it yourself?

I'm not trying to bad mouth anybody in particular here but if you were say looking for some kind of Chimney Liner online retailer that sells parts accessories and "kits" there's several Depot retailers. I have hinted at the one that I used, and while I did eventually get the heavy duty flex liner (after the initial sales person talked me out of it and Bholler informed me I had ordered one step up from drier line) and it only took an additional month, a replacement adapter for the one in the kit that I had mauled trying to pry into submission. Three cuts of the liner inside my house with a grinder and three phone calls after sending in a piece of the liner they manufacture for them to realize what I told them after my attempted weekend install about their adapter being 1/4" undersized for their liner...they eventually made a "custom" one that slid on like it was supposed to. They didn't charge me for the whole mess though I did end up spending around $1150-$1300on the kit for a 25' chimney. If I ever have to do it over again, I would probably go with a different retailer. They are also known as express, and I don't trust the garbage lowes or HD prices 200% higher than cost for their products. HD is better than lowes imo because they actually have milwaukee tools at some competitive prices.

 

[double-d]

As mentioned above there a number of on line dealers that have them and some advertise here on Hearth.com. You need to know what you want and need, don't always leave it up the the retailer, they may not always have your best interest in mind.
When you call them, some have technicians that are very helpful and some are just order takers. Make sure they have them in stock and they can ship them out that same day, or do they have to ship from another location. Always ask if there are discounts available, some do offer them or will price match. You should be able to get a 316ti flex liner in the $400 plus range, and many options are available.

 

[patrickoneal]

Thanks for the advice. I keep running into bholler's posts about liner quality while I'm researching this.

I think I've settled on the Olympia Hybrid preinsulated liner in 304 stainless. It seems like a decent product, and doesn't really seem to cost much more than the thinner "forever flex".

Is that Olympia Hybrid liner decent? I know the inner liner is thicker that some, but not as thick as in the uninsulated heavy duty liners.

 

[double-d]

Olympia, IMO, has a very good liner selection. I don;t think you would have a problem with that liner. I know that they have the Pre-Insulated liner and Hybrid liners. The Pre-insulated liner I believe is about 7.25" OD so you shouldn't have any trouble getting it through a 12 x 12 flue.

 

[bholler]

Is that Olympia Hybrid liner decent? I know the inner liner is thicker that some, but not as thick as in the uninsulated heavy duty liners.

yes hybrid is a good liner it is not as thick as their armor flex but it is still much thicker then lightwall (forever flex) It should give you many years of good service. We use it on woodstoves at times especially new stoves. Older stoves we go with the full heavy wall liners for durability.

 

[patrickoneal]

The best price I've been able to find on the Olympia Hybrid pre-insulated liner kit(liner, clamp, top plate, appliance connector) in 6"x20' in 304 stainless is $676. Is that about the going rate? Or can someone suggest an Olympia reseller that gives better pricing?

 

[Xtrl9]

The best price I've been able to find on the Olympia Hybrid pre-insulated liner kit(liner, clamp, top plate, appliance connector) in 6"x20' in 304 stainless is $676. Is that about the going rate? Or can someone suggest an Olympia reseller that gives better pricing?

I couldn't find anybody that would sell olympia liner to the consumer directly. All the local shops had it or homesaver but only one with homesaver would sell me the liner.

 

[bholler]

I couldn't find anybody that would sell olympia liner to the consumer directly. All the local shops had it or homesaver but only one with homesaver would sell me the liner.

It is now available from several online sources. Which bothers me only because olympia always claimed they would never do that. And their service to us pros has suffered some since that move. They are still good but it takes longer.

 

[patrickoneal]

I tried to get a tight measurement for the liner length tonight. I previously tried fishing a tape measure up the flue and was unsuccessful. Tonight, I fished 2 10' lengths of sch 80 PVC conduit up the chimney until I heard it hit against the rain cap. The bottom of my conduit was 17" from the bottom of the fireplace. The rain cap looks to stand at least 12" above the top of the chimney, so from the top of the flue to the bottom of the fireplace, the measurement should be about 20' 5". Would it be exceptionally foolish to order a 20' liner rather than pay the extra to get a 25'? 20' seems to be cutting it awfully close considering the few inches clamped above the flue, and the length lost bending through the damper and toward the stove.

 

[bholler]

In a case like that we would order 20' but we also have couplers and extra pieces of pipe if it comes up short.

 

[patrickoneal]

One last question....

How clean does the chimney need to be prior to installing an insulated liner?

Looking through the damper, the flue tiles look clean to me, but it's hard to get a good photo(they appear clean and tan to the eye):



There's a bit of black on the mortar between the bricks above the smoke shelf before the flue tiles:



I've lived here since 2008, and I've only burned vent-free gas logs with the damper closed, so I don't know what's really considered "clean". The house was constructed in 1964, and the previous occupants may have burned wood.

 

[Destructor]

That looks very clean, though the smoke chamber should have been parged.

 

[Xtrl9]

When I did my install I spent a good 3 hours cutting and cleaning the smoke shelf/damper/ash/brick/mortar droppings to be able to fit my liner down into the fireplace from the flue. So you should take a look at that to see if you might need to notch out some metal/stone. Perhaps feel around up there now to see how much debris is on the top side and remove what you can now. if you do have to cut it, I would really highly recommend a face shield.


About the smoke chamber, is that ok to be made out of regular brick? mine was fire brick all the way up to the clay liner.

 

[patrickoneal]

Yeah, I'm definitely going to have to notch out the back of the damper and some of the brick on the smoke shelf to fit an insulated liner. You're right on the face shield, I was just going to go with safety glasses but a face shield seems like a better idea.

As for the regular brick, I don't know.

 

[Destructor]

If it is a hard brick such as sewer brick it is fine, especially if it is 8” thick but it should be parged. Firebrick would be my preference but firebrick is more expensive. Brick on an outside chimney that is against the house I would want 8” solid brick with staggered joints. I'm not certain what code is now. I think it is a minimum of 6" if lined with a clay smoke chamber. Whether it is firebrick or plain red brick the mortar joints are what will most likely deteriorate.

 

[patrickoneal]

That's not a problem for me since I'm installing an insulated liner?

Also, I've got a gas pipe coming in the side of the fireplace near close to the bottom that's currently feeding a set of gas logs. I'm perfectly comfortable with removing the pipe and installing a cap or plug outside of the fireplace in the garage.

What do I patch the hole with? Do I need refractory cement? Or would plain mortar or hydraulic cement work in that application?

 

[patrickoneal]

Here's the pipe:


It looks like whoever put it in wasn't too good at using a rotary hammer and dinged up the bricks around the hole.

 

[Destructor]

Regular mortar. My description of a well built smoke chamber would be for a fireplace being used as a fireplace. Your smoke chamber looks to be in good condition. Someone will probably chime in on insert installations. I haven't built any chimneys for a long time so I'm not up on all the latest codes.

 

[bholler]

That's not a problem for me since I'm installing an insulated liner?

No it is perfectly fine

 

[patrickoneal]

I got the gas logs out tonight, demoed and capped off the gas pipe, and hammered out the larger liner pipe that the 1/2" gas pipe ran through(that was fun). I've got some mortar to mix up in the morning. Hopefully my liner shows up next week.

I'm going to be cutting out the back of the damper, and at least some of the top row of fire brick to fit the liner in. Can I just cut out the entire rear part of the damper frame and remove the entire top row of brick? That would really open things up and make the block off plate quit a bit simpler to install. The fireplace is rather tall, so I wouldn't really lose much working space with a lower hanging block off plate.

Thank you all again for all the advice. I like to do things right, and hearing from professionals and enthusiasts is really helpful.

 

[bholler]

Can I just cut out the entire rear part of the damper frame and remove the entire top row of brick? That would really open things up and make the block off plate quit a bit simpler to install. The fireplace is rather tall, so I wouldn't really lose much working space with a lower hanging block off plate.

yeah that should be no problem at all

 

[patrickoneal]

yeah that should be no problem at all

Thanks again. I got the rear frame of the damper out, and removed the two center bricks. The outside bricks were in pretty tight, and I decided not to mess with them because it might disturb the side wall. I've got plenty of clearance now: