Maximum Chimney Height - Wood Insert

[Brigcoals]

We plan to get a wood insert and had a dealer/installer measure today. They said my chimney was too high for the Lopi Large wood insert - it has to be between 15' and 33' - and would create too much draft. Asked about a damper but said the Lopi couldn't be installed with that chimney height.

The height is probably 36-38'.

Are there large wood inserts that work for this chimney height? I've been researching and many only give a min height but not a max.

Thank you!

 

[stoveliker]

Inserts make make dampers hard to mount.
And yes, that would likely be too tall.

Some folks add multiple key dampers in the flue of their (free standing) stoves.

If you have a way to access the dampers,.so you can start the insert with the dampers open, and close them when it's heating up, then it might be possible - but you're going to have an uphill battle.

If you do this, I strongly suggest to add a draft measuring device (magnaehelic or other) so you know what you're doing.

 

[Brigcoals]

Thanks stoveliker, I'm not opposed to adding dampers (cost permitting) but hopeful there's other brands that have a wider chimney operating range.

Would welcome suggestions to research if anybody knows of inserts that may work. I don't see a max height (only min) for some Pacific Energy and Blaze Kings so going to call on Monday to get their views.

 

[stoveliker]

I think most (if not all) stoves are designed for under 25'.

But then it's not the height that matters but the draft.
BK specifies the draft - and all stove mfgs should do so. A BK would be far out of spec on a 35' flue.

 

[Brigcoals]

OK, if that's the case I may have to give up on the idea of an insert. Would be very disappointing.

 

[stoveliker]

Dampers, if technically possible, are not expensive. The way to access them with an insert might be though.

Maybe @begreen or @bholler knows off inserts that operate on taller chimneys.

 

[begreen]

36-38' is a tall flue for any stove. A good, experienced installer/sweep will understand the issue. The height may make using a smaller liner to be considered.

If there is a bit of headroom above the insert then a damper may be installed at the appliance adapter with a linkage fashioned to permit an extension to be attached the projects through a hole drilled in the surround. There are some past examples in this forum. It's not rocket science, but it is custom work and will add an hour or two of billable work to the job.

Insert Key damper install

I finally installed a key damper on my Lopi Freedom, I think it will be the only way to get good control of the fire and a long burn time without smoldering the fire. I installed it through the appliance adapter and the heavy wall liner. I blocked off the hole in the center of the damper for...

www.hearth.com

 

[Brigcoals]

I have a sweep coming at the end of the week and will discuss this possibility with them. Sincerely appreciate the thoughts and help here.

 

[EbS-P]

It can be done. Pay attention to the different damper designs. Some have holes some don’t. You probably want the one with no holes.

Point of reference. I have 23’ of insulated liner and run my insert with a damper (with holes) normal hot reload will need to be opened to reload then closed 85% then fully closed once secondary burn kicks in.

 

[Brigcoals]

It can be done. Pay attention to the different damper designs. Some have holes some don’t. You probably want the one with no holes.

Point of reference. I have 23’ of insulated liner and run my insert with a damper (with holes) normal hot reload will need to be opened to reload then closed 85% then fully closed once secondary burn kicks in.

Excellent, that's encouraging. I'm out of my depth so going to need to find the right installer who can assist with these details.
Thank you

 

[EbS-P]

Excellent, that's encouraging. I'm out of my depth so going to need to find the right installer who can assist with these details.
Thank you

Should have clarified the damper can be done. The install will still need experience that goes beyond what I can offer.

 

[joop]

i have about 34' but at 5 feet i have a 90 degree into a tee,helps slow things down i guess.free standing stove

 

[fao1989]

Hi,
Following up on this thread.
Purchased an Ashford 25 last Jan. Burned about a 6-8 times last season. Twice so far this fall. No issues, happy with the performance. The insert is installed in first floor fireplace of an older two story home, with a masonry and brick fireplace. Chimney top clears the roof, and I think the flue length is likely about 18-22 feet, from flue collar on the stove to the top (using Pythagorean math lol) - maybe a bit less.

Before purchase I noted the minimum height, but never had any thought to a max height. Dealer seemed professional enough.

I have adequate draft, not roaring, but steady pull on flames toward the flue with door cracked, before latching it when starting up. After latching, initial fire responds well to 15-20 mins WOT to activate the cat before engaging bypass door. Then I gradually turn the thermostat all the way down for a longer overnight burn. i'm burning pretty dry wood , less than 20%mc

Did not have enough knowledge to ask about a flue temp sensor when getting the insert installed. Absent that flue temp device, is there anyway to tell if I ever approach high temp limits? Fan air exit point (just above the top lip of the door) at hottest time of the burn reaches about 400-450F. Insert top face heats at that point to about 165-180F.

How should I satisfy myself that insert would not be subject to overheating/over firing the flue? No reason/cause to think this - perhaps just inexperience and overabundance of caution. I've not run WOT for long time, as some have suggested. I've read elsewhere (somewhere in this forum?) that BK themostatic stoves/inserts have a function to shut/close the intake air if temps exceed some limit as a safety measure - is that true?

I'm reluctant to pull the insert simply to put in a flue sensor. Mainly as it is a tight fit and I'd probably need to call the dealer for an assist.

Thanks all!

 

[mellow]

If you can pull the surround off and see if you have room to install a theromocouple probe about 18" up from the flue collar, but you can mount it lower, will just need to adjust what you max temp will be.

Also if you have an exterior fireplace look into if you have room to insulate it: https://www.hearth.com/talk/threads...lating-my-fireplace.75755/page-2#post-1635483

 

[fao1989]

Mellow - thank you. I think I might just have room to get a probe maybe 8-12 inches up from the flue collar.
I did read your threads on insulation and others about block-off covers. I didnt have room for the full insulation shown in your thread, but I did get the BK dealer to do a fairly good metal block off plate in the chimney neck, with rockwool above it. So to get a probe in there I'd probably have to remove that block off plate and, get the probe in, and then re-install the block off plate.

How critical in your mind is a flue sensor?
Do you have recommended brands of thermocouple probes?

Its going down to 24F tonight in Norfolk, so I have the Ashford fired up. The heatpump just wont keep up with these weather temp dips! Tho' prolly not as crisp as you have it up in MD tonight!


Many thanks!

 

[EbS-P]

Mellow - thank you. I think I might just have room to get a probe maybe 8-12 inches up from the flue collar.
I did read your threads on insulation and others about block-off covers. I didnt have room for the full insulation shown in your thread, but I did get the BK dealer to do a fairly good metal block off plate in the chimney neck, with rockwool above it. So to get a probe in there I'd probably have to remove that block off plate and, get the probe in, and then re-install the block off plate.

How critical in your mind is a flue sensor?
Do you have recommended brands of thermocouple probes?

Its going down to 24F tonight in Norfolk, so I have the Ashford fired up. The heatpump just wont keep up with these weather temp dips! Tho' prolly not as crisp as you have it up in MD tonight!


Many thanks!

I put mine in the flue appliance adapter. Yes a standard 18” height to get a standard temp reading is good to compare yours to other installs but. A relative temp reading is all you need to run your stove well. I know 1000 degrees at the collar is something I try to avoid but it will happen and that will correlate with 550 degree stove top temps

I like my Auber at200 (I have both the regular and wireless). The high temp alarm keeps me babysitting it on startup.

 

[fao1989]

I put mine in the flue appliance adapter. Yes a standard 18” height to get a standard temp reading is good to compare yours to other installs but. A relative temp reading is all you need to run your stove well. I know 1000 degrees at the collar is something I try to avoid but it will happen and that will correlate with 550 degree stove top temps

I like my Auber at200 (I have both the regular and wireless). The high temp alarm keeps me babysitting it on startup.

Thanks EbS-P.

 

[mellow]

Auber makes some good units, you could do a thermocouple closer to the appliance adapter, you would just need to set your High temp alarm with that in mind. I used the screw on thermocouple.

Good thread; https://www.hearth.com/talk/threads/temperature-monitoring-wood-insert.200255/