Effective chimney and flue applications

Chimneys operate on the principle that hot air rises because it is less dense than cold air. When a chimney is filled with hot gas, that gas tends to rise because it is less dense than the air outside the house. The rising hot gas creates a pressure difference called draft which draws combustion air into the appliance and expels the exhaust gas outside.

The importance of insulation
In traditional brick chimneys, the brick structure provides an insulation layer between the smoke and hot gases and the surrounding air. This ensures a good temperature difference between the fire and the atmosphere to promote a good draw. Unfortunately, with old fashioned open fires the draw was too good and a big proportion of the heat generated was lost up the chimney. In modern tubular metal chimneys and flues, a specific insulation layer on the outside of the structure is necessary for optimum efficiency and fire safety. The better the chimney – the more effective the draw – the more efficient the fire.

The Promat HPI range of insulation solutions
Promat HPI is successful in this application because of the variety of insulation solutions that we can offer. Powder and granular insulation that can fill a difficult void, and flexible panels of insulation that can be wrapped around cylindrical shapes are just two of the options available. We support our product range with almost 50 years experience in this industry backed up by the best service and support package of any insulation manufacturer. A Promat HPI solution is cost effective and will not be beat on performance.

The challenges for insulation to chimneys and flues

Best possible control of heat loss
Most compact insulation systems for internal use and penetrating building structures
Long working life essential for insulation without aging deterioration, shake down, or other impairment of performance

Easy assembly of insulation components. Availability of pre-tailored items for fast installations of complicated sections
Auto fill capability of powder insulations
Non-combustibility for fire safety in building structures
Fast ROI for insulation – cost effective system design

Promat HPI can offer insulation solutions that solve all of these design needs. By choosing from the broadest product portfolio on the market we can design an "engineered solution" that best meets all design challenges. With access to the very best microporous, calcium silicate and fibre insulation products, a Promat HPI system cannot be beat on performance.

Application solutions

Chimney shaft construction

For fire safety and architectural reasons, a shaft construction around a chimney must be built when necessary for compliance with local fire regulations. This is especially relevant for chimney penetrations through a wooden floor , ceiling and roof. Promat HPI offers a wide range of different large sized refractory and fireproofed structural construction boards such as:

PROMAFOUR®
PROMATECT®-H
PROMATECT®-L
PROMATECT®-L500

Chimney and flue insulation

Promat HPI offer unique solutions for control of heat loss from these structures. Chimneys and heating system exhaust flues can be a safety problem when routed outside the building. Accidental contact can result in a serious burn. Excessive surface temperature can also be a fire hazard with building components such as a thatched roof.

Also, a successful “chimney draw” is dependent on the following principles:

The difference in air pressure between the appliance and the top of the chimney. (Created by the height of the chimney)
The difference in temperature between the appliance’s exhaust gas and the outside temperature
The quality of insulation along the length of the chimney
The route of chimney. (The straighter and more vertical the chimney the better)

The solution is to use an insulation that can flow into confined spaces and consolidate to provide effective protection.

Promat HPI offers a wide range of flexible and pre-shaped pipe insulation to wrap around chimney pipes covered with protective cladding for weather protection when routed outside a building. Inside the building structure it is important to isolate the hot metal structure from direct contact with building materials such as wood and thatch to eliminate fire risk. This is particularly important where a flue penetrates the building structure on exit from the appliance because at this point it is likely to be close to its hottest temperature.