Woodburning Facts and your Chimney Sweep
Everyone loves the glow and warmth that is generated by a fire. In ancient days a fire was the mainstay of family and community life. Cooking, light and heat were its main functions. A fire was generally set up in the center of a conical shaped room with an opening at the top for smoke to rise out of. (The early chimney).
In modern times it is either a romantic entity that enhances an ambient atmosphere or it can back up your main heat source or even be your main heat source. Whatever your scenario, this page is for you.
While the primitive chimney was fine in its day, we have more sophisticated means of exhausting smoke from our homes. This is via the chimney. Chimneys can be constructed from a number of building materials. These include....
Brick and mortar with a clay flue tile lining
Blocks and mortar with a clay flue tile lining
Stainless steel prefabricated chimney lengths with an inner core of insulation
Aluminum prefabricated chimney lengths (for natural gas (NG) and propane (LP) fired units only)
New chimneys of masonry construction can now be erected with a stainless steel chimney liner instead of the traditional clay flue tiles. These liners must have passed the code for new construction and have 10-25 year warranties.
The chimney is the engine that drives your appliance. It is where the draft is established to encourage a proper burn. A chimney flue that is too narrow or too large for the appliance will NOT draw properly and will make the attached unit perform badly and can result in an accumulation of deposits within the flue channel. With wood these deposits are known as soot and creosote. For LP and NG units this is carbon powder.
Either way, excessive deposits are a problem waiting to happen.
In this section we will first deal with woodfired appliances primarily
Woodstoves, fireplaces, inserts and furnaces should be swept and inspected on a regular basis to avoid any incidence of chimney fire. Soot and creosote are byproducts of incomplete combustion within the burning system. This can be caused by improper fuel loading, low burn habits, poor grade firewood or an improperly sized chimney flue.
A low burning fire tends to make the combustion phase a smoldering production while a brisk hot fire makes for a great burning environment. To understand this you must begin to understand the basics of how wood burns.
How Wood Burns
When wood burns it goes through a chemical process called combustion. Combustion is easily explained by this formula.... Fuel + Heat + Air = Carbon Dioxide + Water Vapour + heat + Air.
In a perfect world this is Complete Combustion, this rarely happens. What we generally get is an excess of hydrocarbons produced which form into soot, crosote and tarry substances. There are several different processes that happen with wood before the flames erupt.
Phase 1: The water must be vaporized.
You all have probably heard the HISS of wood as it is put into a fire. This is the water beginning to heat and boil away. Once this is complete then phase two can begin.
Phase 2: Pyrolysis.
This is the drying and decomposing of the wood and the breakdown into chemical origins. The wood is preparing itself for the burn phase.
Phase 3: Is about to begin. The hydrocarbons are beginning to combust (burn). Oxygen mixes with these chemicals and starts to produce heat and light (flames). You may feel the heat in this phase but you may not see the flames, yet.
Phase Four: Combustion period. The wood has sufficiently dried and changed its composition into charcoal. Charcoal is carbon and carbon burns. When a good supply of oxygen is introduced in the burn cycle, carbon dioxide is created (CO2) if not enough oxygen is introduced the Carbon Monoxide (CO) is produced.
CO2 is a necessary chemical in our everyday lives. Plant forms ingest this chemical in order to help them grow. Every animal exhales CO2 with every breath and the plants around us 'breath' it in and produce oxygen for us to breath. It is a sybyotic relationship. Even decaying wood in the forest produces CO2. Although the production is slower that that produced by wood burning, wood expels CO2 no matter if it is left as deadfall or burned as fuel.
CO [Carbon Mon-oxide] on the otherhand is an odorless, poisonous gas that is harmful to any lifeform. (see section on CO Poisoning). If it builds up into a concentrated form you will get sick and can die. This CO can be produced by ANY fuel burning appliance from kitchen ranges, to heat-stoves, fireplaces and furnaces. Even your gas fuelled dryer or hot water heater can produce CO if not installed and vented properly.
CO is not fuel specific.
The Chimney Sweep
A chimney sweep should be a trained chimney technician who can rid your flues of accumulated deposits and set your unit to running smoothly again. He/she should be able to tell you if there are any problems in your system and should be able to steer you into corrective measures to ensure your safe burning habits.
In order to find a well trained and professional sweep you should look for a few credentials from him or her before you hire them. A Word-of-mouth Referral is a good start; ask a neighbour, relative or friend who they use and why.
In your initial telephone call to the sweep company, you should ask several questions before hiring. Your questions can be any of the following.
How long has the company been established?
How long has the sweep(s) been with the company?
What sort of training do they have?
This is where the chimneysweeps office should go into the WETT (Wood Energy Technical Training) aspect of their talk with you. They should mention that WETT Inc. (the training body) Certifies only the
INDIVIDUAL Technicians, NOT their company.
All WETT Certified Sweeps, Advisors, Installers carry photo-wallet cards that are currently dated and show their own personal WETT Certification Number. This Certification must be renewed yearly. The Technician will get a new card every year.
To find a WETT Certified Sweep Near you Email to
WETT Inc. and ask for several names.
Also ask if they belong to any Trade Affiliations, Guilds or Association.
They could be members of the
Chimney Safety Association of Canada (CSAC) which have members all across Canada, they could be members of a WETT Provincial Affiliate (WET-BC=British Columbia.,etc.) or the National Chimney Sweep Guild or NCSG. A WETT Certified Technician WILL have photo-Identification with them. Ask to see it... The companies Yellow Pages ad should display some if not all their affiliations.
Then ask WHAT the technician/sweeps will clean when they come to your home.
A sweep should clean everything from the firebox or stove through any connection pipes, and the entire chimney.
For a fireplace this must include the smoke shelf and chamber.
For a stove it must include ALL smoke pipes, chimney and the breach area which connects the chimney to the smoke pipes and chimney.
For furnace flues that are not wood fired, your oil or gas company should clean and service the furnace itself AFTER the chimney is swept. The furnace may require recalibrati to the flue size for proper combustion. This will depend on the amount of residue removed from the chimney flues interior.
Once you have satisifed your requirements with the sweep company of your choice, set up an appointment and before he/she arrives please do the following...
Make sure the fire is out and has been for several hours. No sweep likes to burn themselves or their equipment on a hot appliance and chimney.
Remove as much of the accumulated ash and wood bits from the firebox or stove that you can.
Remove any delicate figurines from around the unit.
Keep pets and children away from the worksite.
If you do the above, your relationship with your sweep will get off on the right foot and the sweep can get down to the job at hand and not worry.
When the sweeping procedure is completed the chimneysweep should have left NO MESS behind him/her. The chimney should be free running and be empty of all residual soot and creosote deposits.
Ashpits
The Sweep does not generally clean out the Ash-pit below a fireplace. These areas can sometimes be cavernous and time consuming. The homeowner should make it their responsibility to remove this ash themselves. One or two buckets a week until empty.
I have personally seen ashpits with wood beams running across them that have been blackened by falling hot embers and ash that has been swept into them. I advise people NOT to use them if they can avoid it.
Glazed Creosote
Glazing (burnt on soot)is another matter....it is impossible to remove with a simple brushing. It is concentrated soot and highly flammable, it should not be left to build-up to dangerous perportions. In this case, the sweep may recommend another method of glaze removal. This could be by using a chemical catalyst (like ACS spray) or by a special method called Ro-Kleening (RK). Do not trust any product that claims to free your chimney of creosote with its use! All glaze must be manually removed after ANY product or method is used to remove it.
The RK method of glaze removal can be accomplished in a time frame of 1-6 hours, depending on degree of glaze. It is performed with a specially designed mechanical head that literally whips the glaze from the tiles or stainless steel chimney without harming the chimney interior. There are two heads, one for masonry chimneys and one for prefab steel chimneys. Used in the proper application, no damage will be done to the chimney itself.
Evaluations of system
A qualified sweep will also look into the condition of the inner flue and smoke pipes and advise you, in writing, of any deficiancies they discover. Broken flue tiles, spawling brick, warped dampers/baffles, clearances to combustibles, hearth size, chimney height,etc.
They are not noting these things to scare you, but to make you safer.
They may recommend a rain cap to prevent moisture from coming into the flue and causing deterioration of the inner linings and brickwork. Most caps also have a good, heavy duty screen to prevent birds and wildlife from entering the flue and causing a blockage with nesting materials. A quality cap is a good investment.
The Ontario Fire Code (and many others) state that
"Chimneys and flue pipes should be inspected annually and cleaned as often as necessary to keep them free from combustible deposits."
How Often Should I Clean My Chimney?
On the average a woodburning unit should be swept EVERY year or after every bush cord of wood has been consumed. If you are a constant wood-burner and use your unit for primary heat you will require 3-4+ sweepings per season. The last sweeping should be done in April or May to rid your system of the corrosive soot deposits that can eat into your chimney when left to sit for several months. Your sweep can also set up an appointment for any reparation work that may be needed for the summer months, when the unit is not used. Then come fall's chilly winds, your unit is up and ready for you to burn brightly and safely again.
Combination Furnaces such as Wood/oil & wood/electric furnaces should be serviced as often as if it were a wood only units. Every full cord of wood constitutes a sweeping and service check. For wood/oil combos remember, Oil residue is sticky and will attract any airborn debris, including soot.
Gas/Propane chimneys should be inspected after the first year of burning and there-after when necessary. The first inspection will determine the deposit amount within the flue channel. Your fuel air mixture may need adjusting if excessive carbon deposits are found. Full chimney Cleanings may be only necessary every 3-5 years. The gas/propane appliance however should be serviced every spring just as your furnace needs adjusting and tuning up so does your appliance. Motors should be oiled, fans dusted and glass cleaned. This will ready the appliance for next seasons burning cycle.
Pellet burning units should be swept after EVERY ton of pellet is consumed, and have their ENTIRE inner workings cleaned and oiled every three tons. This prevents clogging of the auger and auger motor and proper running of all fan systems. These units require annual unit maintenance and just like the NG & LP units they have fans, motors, thermodiscs and glass which needs expert care..
Natural Gas, Propane and Pellet units are being sold by some retailers as maintenance free units...
DO NOT BELIEVE THIS...
Generally they can be less maintenance free than a wood unit. Yes, the fuel is more convenient but, the maintenance is more constant. You must remember that these units are MECHANICAL. A full spring tune-up and check of these appliances can run you triple the charge of a woodburning unit. They have many complex moving parts to deal with; spill switches, thermodiscs, 1-3 different fans, motors, augers, etc.
And just like your car, these units cannot run properly if all you do is put fuel into them. They need the expertise of a qualified service person to deal with the unit itself as well as the chimney system it is hooked up to.
Be a friend to your heating appliance and it's venting chimney system, and have them serviced regularly by a QUALIFIED Oil or Gas Appliance Technician or WETT Certified Chimney Sweep.
