TherMix Chimney Insulation

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Use TherMix Insulation with Chimney Liner

If you are looking for a way to fill the gap between your chimney liner kit and the walls of your chimney then look no further than TherMix Chimney Insulation by Duravent. This amazing ready to mix compound can easily help fill gaps and cracks in the walls of your masonry chimney as well as offer an added layer of protection for your chimney liner system.

TherMix is a thermal ready to mix compound used as an insulation barrier for masonry chimneys and chimney liner kits

DuraVent presents TherMix, a ready to mix, Vermiculite based masonry material. Ther Mix cures into a lightweight, semi-hard compound that forms a thermal insulation barrier. This barrier works to keep flue gases warm and exterior chimney surface temperatures within safe limits. Additionally, TherMix acts as a masonry filler. When poured into the masonry chimney, TherMix fills the voids and cracks that could be found in the chimney walls. This eliminates airflow and moisture build up between the liner and chimney. This helps increase efficiency in your system as well as provides better draft for your chimney liner kit and heating appliance.

Ther Mix is listed by Underwriters Laboratories (UL), under UL 1777, in combination with several brands and types of lining materials for use in applications where chimneys are in direct contact with framing or other combustible materials. The Ther Mix has a zero clearance requirement between the chimney liner and the walls of the chimney,

It is important to note that using Ther Mix by itself does not replace the need for a chimney liner. It is also recommended to check with state and local building codes before installing to make sure that it is allowed for use in your area and for your specific project

There are several Benefits of using Thermix as a spacer between the liner and chimney walls.

  • No Health Risks: Non-fibrous, non-toxic, inert and manufactured under stringent quality controls. Safe to the installer and homeowner, today and into the future.
  • Adds Safety: Chimneys insulated by TherMix reduce creosote build-up, the chance of a chimney fire is minimized and its dangers are decreased.
  • Holds in Place: Securely holds Chimney Liner in place
  • Superior Performance: Featuring high "R" values, flue surface temperatures are balanced and react quickly to firing cycles of heating units. Aiding in optimal heating efficiencies.
  • Durable & Tested: When properly installed, TherMix does not leak, separate or deteriorate. Field tested since 1984.
  • Reinforces: Insulates the liner & flue gas while providing a strong bond for the masonry chimney.
  • Easy to work with material: Strong enough to hold in place but easy to remove if needed

TherMix creates a barrier that can seal dangerous cracks and block air gaps

TherMix Chimney Insulation is best used to fill the space between a chimney liner and the inside walls of a masonry chimney. This convenient ready to mix formula cures into a lightweight semi-hard mass that insulates the liner and dissipates the intense heat created in a chimney fire. TherMix Chimney Insulation can be used to insulate modular masonry chimneys and is designed to seal dangerous cracks in the chimney. TherMix also eliminates air gaps and moisture buildup between the liner and chimney walls.

TherMix is easy to use and installation is a breeze

TherMix is delivered in a strong poly-lined bag or box containing all ingredients except water, which must be added to moisten the material. Proper consistency is achieved when the material feels damp but still granular (~7 to 9 gallons of water per bag/box).

*When a handful of properly moistened TherMix is squeezed hard, little to no water appears between the fingers.
During the installation, correctly prepared TherMix pours like "loose fill." TherMix is distributed within the chimney cavity byvibrating the liner. It is important to not tamp or compress TherMix.

To determine the amount of TherMix Chimney Insulation that you will need for your project, refer to the product manual. Page 4 of the manual has a helpful chart to determine how much TherMix you will need for your project.

FAQ - TherMix Chimney Insulation

What does TherMix Chimney Insulation actually do?

TherMix Chimney Insulation fills in the space between your chimney liner kit and the walls of your masonry chimney. This insulation helps fill in any gaps that are in your chimney wall cavity and it also helps to insulate the chimney liner pipe. This added insulation keeps moisture off of the outer wall of your pipe and also can improve the draft and function of your chimney liner.

What is TherMix Chimney insulation?

TherMix Chimney Insulation is a ready to mix Vermiculite Masonry material that when mixed with water forms a strong compound to fill in the open space between your chimney liner and masonry chimney.

Which Thermomix brand is the best?

Northline Express offers TherMix products manufactured by DuraVent. DuraVent is a well known brand that specializes in manufacturing venting products for residential, commercial, and industrial applications. They offer a wide range of venting solutions for various fuel types, including gas, wood, pellet, and oil. They have a dedication towards creating long lasting, quality products and are one of the most trusted names in the industry.

Where can I find Chimney Liner kits and components?

Northline Express offers a full line of Chimney Liner venting, kits, components and accessories.

Where can I go to learn more about Chimney Liners?

You can check out our resource center where we feature some of the following articles:

TherMix Chimney Insulation Specifications:

  • Zero Clearance to Combustibles
  • Can be used to insulate modular masonry chimneys
  • Delivered in a strong poly lined bag
  • Contains all ingredients except water, which needs to be added to moisten the material
  • 7 to 9 gallons of water is needed per bag
  • Ther Mix stays in place but can be easily removed if needed
  • Manufactured by DuraVent
  • Weight 40 pounds
  • Does not qualify for Free Shipping
  • Does not replace the need for a chimney liner or chimney venting.
Use to fill space between a liner and the inside of a masonry chimney. Ready-mix formula cures into a lightweight semi-hard mass that insulates the liner and dissipates the intense heat created in a chimney fire.
  • This Product does not qualify for free shipping
17.00 (in)
7.00 (in)
26.00 (in)
Additional Information:
  • This Product does not qualify for free shipping
Country Of Origin:
United States
Chimney Liner Pipe
Product Type:
Chimney Pipe
Product Weight:
40 LBS
_Base Price:
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