Says I cant install a ss insulated liner in a masonry chimney.

[wttaylors]

On Fri, Oct 30, 2026 at 4:42 PM Bill Taylor <bill@floridadredge.com> wrote:
I sent the email below to the now second chimney service company in the area. Both have great reputations. The reply below the email has me stumped.
I am hoping someone here can weigh in with other solutions. Best Regards In advance to all, Bill

As promised, a short work scope,
The home was built in 1955. The masonry structure in the middle of the home is 9 feet wide and was built with 3 Heatilators, one in the basement and two on the main level. We only wish to tackle the living room. Our goal is to have a small, open hearth, wood burning fireplace. The Heatilator in the living room was removed by myself with hopes that a chimney/fire mason could install a Majestic 36", open hearth prefab unit, https://downloads.hearthnhome.com/installManuals/4010_259.pdf. The fire box opening into the living room is approximately 34.5" wide by 21.25" deep by 26" tall . There is a steel angle lintel at the top. From the lintel looking up inside about 10", the masons began corbelling in for the shape of the Heatilator smoke dome as can be seen in the photos, https://drive.google.com/drive/folders/17qlUVO4PXVaxCMn0Tt99pobk9UgNNTsk. As seen from the Majestic instructions/drawings, that unit is about 42" tall, which means some corbelling will have to be removed as well as installing a new lintel at a higher location. The fireplaces and chimneys were inspected in January 26 and again in October 26 by two different chimney sweep services. Where, it was determined, the smoke domes were rusted/rotted, and the terracotta liners were in need of repair. It's probably more cost effective to line those with SS new, but I will defer to you. On the flip side of the fireplace in the living room is another Heatilator in the kitchen. I will remove that one as well. We are going to install wall ovens in that place. That means more brick (including corbelling) needs to be removed, and another new lintel needs to be installed at a higher location. The kitchen fireplace is the painted one you see in the later part of the photo dump. It is not directly behind the living room one, but one brick offset, adjacent. I have attached the first inspection report from January. In it, you will note, they called out the terra cotta liner for the living room has an ID of 10.25 inches. I have measured the same. Unfortunately, the prescribed flue liner that majestic received the UL listing with has and OD of 10.5 inches. That means 12 feet of straight liner needs to be broken out. We have no desire for heat efficiency in a fireplace. This is strictly for ambience. We chose the Majestic over other brands based on the depth available only. We are not interested in a PriorFire or Ahrens, etc. If there is another, reputable, us made, prefabricated wood burning open hearth unit, that will fit in this space, we are open to that. Feel free to call my cell below to discuss.
Hope this is not too much.
Best Regards

Bill



Bill Taylor
Project Engineer

FD&D

Tarpon Springs FL

727-942-7888 x410

727-410-4138 cell

The email i recieved

Hi Bill,

Thank you for reaching out and providing the detailed scope of work and photos.

Regarding the installation of the Majestic factory-built fireplace, we cannot install a Factory built fireplace unit inside a masonry fireplace. Modern factory-built fireplaces are engineered, certified, and tested to operate strictly within their manufacturer specifications, which require venting into a metal flue inside a wood chase.

Installing a factory-built unit into a masonry cavity introduces several safety and performance issues:

- Heat & Clearances: It can alter the thermodynamics, trap heat improperly, and violate required clearances to combustibles.
- Drafting & Creosote: Factory-built fireplaces rely on controlled burning dynamics. Pairing the metal chimney with a masonry flue or cavity can cause poor drafting, severe creosote buildup, and backdrafting.
- Safety & Compliance: Modifying a prefabricated unit or venting it outside of its tested and listed scope breaks safety regulations and voids its UL certification.

Please let us know if you would like to discuss alternative options that comply with safety and building codes for your masonry setup.

Best regards,

_------- Chimney Service

 

[begreen]

Looks like installing a non-cat insert with an insulated liner may be the best solution.

 

[wttaylors]

Looks like installing a non-cat insert with an insulated liner may be the best solution.

If i understood you. You are suggesting a closed stove over an open hearth?

 

[begreen]

An insert can connect to an insulated liner inside of the current masonry flue. The finished look is like a fireplace with a door on it. Some inserts permit an open door with a screen on it. Was there firebrick in the installation? If none, code requires 10" of masonry surrounding an insert or 8" if firebrick is installed.

There are several installation examples here in past postings. Search on "heatform".

 

[bholler]

On Fri, Oct 30, 2026 at 4:42 PM Bill Taylor <bill@floridadredge.com> wrote:
I sent the email below to the now second chimney service company in the area. Both have great reputations. The reply below the email has me stumped.
I am hoping someone here can weigh in with other solutions. Best Regards In advance to all, Bill


The email i recieved

Hi Bill,

Thank you for reaching out and providing the detailed scope of work and photos.

Regarding the installation of the Majestic factory-built fireplace, we cannot install a Factory built fireplace unit inside a masonry fireplace. Modern factory-built fireplaces are engineered, certified, and tested to operate strictly within their manufacturer specifications, which require venting into a metal flue inside a wood chase.

Installing a factory-built unit into a masonry cavity introduces several safety and performance issues:

- Heat & Clearances: It can alter the thermodynamics, trap heat improperly, and violate required clearances to combustibles.
- Drafting & Creosote: Factory-built fireplaces rely on controlled burning dynamics. Pairing the metal chimney with a masonry flue or cavity can cause poor drafting, severe creosote buildup, and backdrafting.
- Safety & Compliance: Modifying a prefabricated unit or venting it outside of its tested and listed scope breaks safety regulations and voids its UL certification.

Please let us know if you would like to discuss alternative options that comply with safety and building codes for your masonry setup.

Best regards,

_------- Chimney Service

Your options are build a new masony firebox in the opening. Do something like an aheren's fire in the opening. Or an insert as suggested. A prefab fireplace like you linked to just isnt feasable