Three basis cleaning tips.

Cleaning method #1

A vacuum cleaner may be used, but never use high pressured air to blow the cells free of any build-up. This can damage the cell walls. Any cell blockage can be removed with the use of a pipe cleaner or a cotton swab as well.

Method #2
Should the combustor’s cells become masked with fly-ash,...use a paintbrush or soft-bristled brush and dust the combustor gently.

Never use anything abrasive to clean the combustor.

Method #3
Normally the catalytic combustor requires little or no maintenance because it generates such high temperatures, it is basically self-cleaning. However, should the combustor become masked with soot or creosote,

it is possible to burn the accumulation off by opening the bypass and building a hot fire. Once the hot fire is created, close the bypass halfway and burn for 30 to 60 minutes with the bypass left in this position.
Never use cleaning solvents to clean it.It would be wise to check and clean the combustor, if necessary, before each burning season and inspect the flue system for any signs of creosote build up.
A clean flue helps prevent chimney flue fires.

When should you clean the combustor?

Normally your catalytic combustor requires little or no maintenance. Because it generates such high temperatures it is basically self-cleaning.

After the first burning the combustor should have a light gray powdery appearance. Should the combustor’s cells become masked with fly-ash, use a paintbrush or soft-bristled brush and dust the combustor gently.

(See my next posting with complete details on cleaning the combustor.)

However, it might be wise to check and clean the combustor, if necessary, before each burning season and inspect all flues for creosote build up.

Cleaning the flue before each burning season helps prevent chimney flue fires.

What if the combustor is not working properly?

-Check your fuel supply for moisture content. Fuel should be seasoned dried wood. Rain and snow are considered moisture and will produce damp smoke and steam. Both are harmful to your combustor, especially when refueling and the combustor is burning hot.

-Check the flue and chimney, making sure the stove’s exhaust system is not blocked nor has any obstructions.-Make sure the stove is getting the proper draft.

-Check all movable stove parts to be sure they are working freely.

-Make sure the combustor has not fallen out of it’s holding device.

-Check the combustor for plugged cells. Follow cleaning instructions.

-Check if the combustor has been in the stove for more than six burning seasons, it might be time to replace it.

-Be sure to follow the manufacturer’s instructions for proper firing. Different manufacturers and stove models require different procedures.as a rule of thumb, the catalytic combustor needs a minimum of 500 F. temperature focused on it for a period of 20 to 30 minutes to achieve light-off. This is done with the bypass in the open position. Nothing but heat will be going to the combustor at this stage. The catalyst will receive the heat it needs in this period of time.

How can you tell if the combustor is working?

The best way is to have temperature monitors or thermocouplings to monitor the exhaust temperatures of the combustor.

When monitors are installed properly and the combustor has had ample time to reach light-off , the exhaust temperatures will rise immediately when the bypass damper is closed. This will indicate the catalyst is operating. Exhaust temperatures are important to monitor. As I mentioned in the last posting, temperatures above 1800° F. (1000° C.) will damage the combustor. Temperatures between 1400 and 1600° F. (760-870° C.) are common, but operating temperatures between 1200 and 1400° F. (650-760° C.) are recommended. Most of this heat is transmitted to surrounding stove parts via thermal radiation.

If you don't have monitors, just go outside and see what is coming out of the chimney. If the bypass damper is closed there should be no dark lingering smoke coming out of the chimney. This will tell you the catalytic combustor is working fine.

Operating temperatures of the combustor.

Combustor temperatures can become extremely hot during operation....

Temperatures above 1800 degrees F. will damage the catalyst.

Temperatures between 1400 to 1600 degrees F. are normal,

but temperatures between 1200 degrees F to 1400 degrees F. are recommended.

The combustor does not have to glow to be working.

What is a woodstove catalytic combustor?

By definition, a catalyst is not consumed or used up. The nature of a catalytic reaction is often defined as:
“A substance, usually present in small amounts related to the reactants, that modifies and especially increases the rate of a chemical reaction without being consumed in the process.”

Firecat combustors manufactured by Applied Ceramics are made of high temperature, honeycomb patterned, ceramic substrate. They are coated with special noble metals. The honeycomb pattern gives the combustor the surface area for the catalytic costing. The noble metals used are palladium and platinum.


These catalytic combustors have been used by the woodstove industry since the first catalytic stoves was designed. Most catalytic stove manufacturers today are still using the Firecat brand as their choice for quality and performance.