Monday, February 20, 2017

Chimney heights

Modern, efficient appliances need modern, efficient chimneys. The selection, location and installation of the chimney is at least as important as the type of wood-burning appliance you choose. A properly designed and installed chimney will give many years of reliable service and will allow your appliance to perform properly. An effective chimney is an important part of any successful wood burning system. Many of the reported problems with the performance of wood burning appliances can be traced to chimney deficiencies of various kinds. Knowing how chimneys work is not only necessary in selecting the correct chimney and designing the installation, but is useful in the day-to-day operation of the appliance.




























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 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 hotter the gas compared to the air outside, the stronger the draft.


 




Thursday, February 16, 2017

Keeping the chimney flue in good shape.


Chimney flues, whether metal or clay lined or made from brick or stone, must be properly maintained to prevent smoke damage, carbon monoxide poisoning or even a house fire. The interior of the chimney should be inspected to make sure it is unblocked and free of excessive creosote buildup. The exterior should be inspected for cracks and inadequate flashing. Check that the damper is open before starting a fire.


During periods of disuse, it isn't uncommon for creatures to set up a home in a chimney. Birds, squirrels, raccoons, bees and wasps are the most common critters found in chimneys and their nests can block air flow from a fireplace. This will make it more difficult to start a fire and more importantly, it may cause smoke to flow into your home instead of up the chimney.

A chimney cap will help to keep creatures out. Use of a spark arresting chimney cap (recommended) will also reduce the risk of a roof fire from floating embers.

Creosote buildup is another important thing to inspect for. Burning wood, especially green wood, results in the accumulation of creosote, a tar-like substance, inside the chimney. Creosote is flammable, and an excess build up can lead to a chimney fire. A build-up of 1/8 inch or more increases the risk of a chimney fire and should be removed.

Inspection of the chimney is best done from the bottom and the top. If you aren't comfortable climbing up on your roof to look down your chimney, you should consider hiring a professional. If after inspecting your chimney, you find that it requires service, this is work best left to a professional.

Use a mirror or lay down newspaper to look up the chimney. Use a powerful flashlight to light your view. When inspecting, look for blockages, cracks, damage and creosote build-up.

Inspect the mortar joints in brick or stone chimneys. Gaps can allow water in, which can lead to extensive damage and it can allow carbon monoxide to flow into a room in portions adjacent to living areas.
 
If you discover a nest in the chimney, you can try to scare away creatures by wadding up a single piece of paper and burn it in the fireplace. The smoke will be minimal but may be enough drive out any lodgers. You may be able to dislodge a blockage using a piece of lightweight PVC pipe. Be sure to use a long enough piece that it won't become lost in the chimney if you drop it. Only attempt to clear a blockage if you can do so safely and have a stable position to work from. Creosote clean-up should only be done by a professional.

Monday, February 13, 2017

Why is 'flame impingement' bad for the catalyst?

 
Direct flame contact is death to the catalyst. A catalyst burns the byproducts in the smoke. The gases such as CO, HC, and O2 ignite with each other in a chemical reaction in the presence of the catalyst (while passing through the honeycomb configuration).
Direct flame inhibits this reaction by changing the chemical make-up of the catalyst breaking down the substrate or ceramic. (thermal cracking)




Today's modern wood burning stoves are designed so that flame impingement is unlikely. However, it is not impossible. A strong fast draft can pull the flames into the catalyst. A hot fire with all the primary air controls wide open or perhaps the firebox door or ash pan door ajar are other ways the catalyst might receive flame impingement.



 

Thursday, February 9, 2017

How to clean the glass on your stove.


Note: It is always important to check your owner’s manual first.

 

1. Wash with ammonia **Recommended** - Make sure fire place is cool to the touch. Fill a spray bottle with a slightly diluted mixture of ammonia and water. The water helps keep the ammonia from evaporating on the glass and makes it easier to use. Some also recommend using some vinegar in the mixture, although this is not necessary.

 Grab some paper towels and spray the glass. Start wiping the black or foggy glass clean. It will take a couple of times to get a clear window depending on how coated your glass is. If there are some unusually difficult spots let the solution sit and react.

Also take your ammonia and water soaked paper towel and dunk it in the ashes in the bottom of the stove. Using this to scour the glass as the ash will aid in the chemical cleaning of the glass. Wipe clean with a dry cloth.

 
2. Use a Commercial Cleaner- There are a variety of products on the market that can accomplish the same as ammonia. Follow directions of whatever you choose, and make sure they do not void your stoves warranty by using a product that will scar the glass.

Monday, February 6, 2017

Main reasons why wood burning systems smoke


 
There are three main reasons why some wood burning systems smoke:
1. Bad system design: There are design characteristics that can make a wood burning system more likely to spill smoke. Most of these characteristics result in low flue temperature and low draft. Outside wall chimneys and long flue assemblies before exhaust reach the chimney are just a couple.
2. Extreme negative pressure in the house: Energy efficiency practice and new building code rules are making our houses more and more air tight. This makes the house energy efficient, but also makes them sensitive to depressurization when air is exhausted from the house. Other exhaust appliances used in the house can cause extreme negative pressure in the house when they are operating.
3. Improper woodstove firing technique: When a wood fire is starved for air it smolders, producing a relatively cool, smoky fire. The temperatures throughout the system are low. During a smoldering fire, the chimney will not be receiving the hot gas it needs to produce strong draft.



And remember, when refueling first open the by-pass before opening the firebox door.

Thursday, February 2, 2017

Is it safe to burn painted wood in your fireplace or stove?


 That is a very bad idea!

Burning treated lumber, petroleum products, painted wood, trash, and such, releases toxic chemicals into the atmosphere (including your home!), and could cause other damage, as well.
For example, a catalytic combustor in a wood stove can be destroyed by certain chemical agents found in these items.
Fireplaces and stoves aren't designed as incinerators, and it is neither safe nor environmentally sound to use them as such.
 
 
 
Stick with seasoned dried firewood for your heating needs. This way you will be protecting your health, and your neighbor’s health as well.

Monday, January 30, 2017

Keep the combustor clean.

If it becomes necessary to clean the combustor, below are three recommended methods.




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 the combustor. 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 buildup.

A clean flue helps prevent chimney flue fires.


Thursday, January 26, 2017

What to do when 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 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 its 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.


Monday, January 23, 2017

How can you be sure the catalytic combustor is operating properly?


Some stoves are equipped with a combustor view port, it should be noted that the combustor usually glows during the first 20 to 35% of the burn cycle when the catalyst is receiving the most smoke and burning at a high temperature. The combustor temperature can reach 1000 F. and produce a glow.

 However, the combustor does not have to glow to be working.  As less smoke is present to burn, the combustor temperature drops and the glow will cease. Therefore, it is suggest this not be a method of determining whether or not the combustor is working.
-The best method is the use of thermo couplings and following the stove manufacturer’s instructions. This method will read the inlet and exhaust temperatures of the combustor.
-A more simple method is to visually observe the exhaust coming out of the chimney. When the by-pass is in the closed position and the catalytic combustor is in good operating condition, there should be no dark smoke coming out of the chimney.



-If the catalytic combustor is not working properly, the stove’s operator will notice an increase in fuel usage.
-The stove’s operator will also notice an increase build-up of creosote in the system.

Thursday, January 19, 2017

Operating temperatures for the catalytic 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.

Monday, January 16, 2017

Firecat catalytic combustor design



The FIRECAT brand catalytic combustors made by Applied Ceramics Inc. come in many different shapes and sizes to fit every catalytic stove ever built. They are made of high temperature, honeycomb patterned ceramic substrate.  They are coated with special noble metals. The honeycomb pattern gives the combustor surface area for the catalytic coatings that are applied.   The noble metals used are palladium and/or platinum.







Thursday, January 12, 2017

How does the catalytic combustor work?



Wood smoke gases coming in contact with the combustor will cause a chemical change to take place. This will then allow smoke to ignite at temperatures around 500 degrees F. (260 degrees C.)  This temperature is easily achieved in the firebox of a wood burning stove.  As the wood gases ignite and burn within the combustor, clean by-products of water vapor and carbon dioxide are emitted.


Monday, January 9, 2017

Starting a cold catalytic wood burning stove


As a rule of thumb, when starting a fire in a cold stove, the combustor must have 500 o F. of temperature focused on it for 20 to 30 minutes to achieve proper light-off.
The by-pass should be in the open position during this period of time.
This will allow the stove, the catalytic combustor and the fuel to stabilize at a proper operating temperature.


Even though temperature can reach 600 degrees F. within a few minutes after the fire has started, if the fire is turned down too soon to a low burning condition (using the primary air adjustment), it will result in the fire and/or the catalytic combustor going out.
At the end of a burn cycle, it’s possible that the amount of burning charcoal remaining might not provide sufficient temperature or fuel for the catalyst to stay lit.
During the refueling stage, if the stove’s firebox has an internal temperature below 500 o F., it is best to fire the stove up for 10 to 15 minutes. (By-pass and primary air adjustment open again)
This will provide increased temperature and proper amounts of volatile gases for the catalyst to operate efficiently.
However, when refueling a hot stove that has an internal temperature above 500 o F., no re-firing is necessary.
Refer to the manufacturer's stove operating manual for complete details.