Catalytic vs. Non-Catalytic Wood Stoves

In catalytic combustion the smoky exhaust is passed through a coated ceramic honeycomb inside the stove where the gases and particles ignite and burn at a temperature that is less than half the temperature required fo rthe combustion of the gases without the catalytic action. Catalytic stoves are capable of producing a long, even heat output. The catalyst can last six seasons or more if the stove is used properly. Over-firing, burning garbage or treated woods, locking the catalyst down at extremely high temperatures which causes thermal shock and neglecting regular cleaning and maintenance can cause the catalyst to break down prematurely.

Catalylic stoves are slightly more complicated to operate.

Non-catalytic stoves utilize firebox insulation and a secondary burn chamber that injects pre-heated combustion air and turbulance through small holes in a baffle system above the fuel in the firebox. Non-cats have less even heat output and shorter burn times than do catalytic stoves but create a more pleasing flame presentation.

The baffle and some other internal parts of a non-catalytic stove will need replacement from time to time as they deteriorate with the high heat of efficient combustion.

EPA vs. Non-EPA Wood Stoves

The EPA certified wood burning stoves burn wood more efficiently and cleanly than traditional types of wood stoves. These wood stoves can provide a nearly smokeless burn, producing maximum heat while using less firewood.

Each EPA certified wood stove or wood heating appliance is tested by an accredited laboratory to meet a particulate emissions limit of 7.5 grams per hour for non-catalytic wood stoves and 4.1 grams per hour for catalytic wood stoves, except in the State of Washington, where these values are 4.5 grams per hour for non-cat wood stoves and 2.5 grams per hour for catalytic wood stoves.

Many older stoves from the 1970's and 1980's that still may be in use commonly put out well over 90 grams of particulate emissions.

Switch and upgrade to a certified stove that is over 10 times cleaner burning!

Additionally, a pre-EPA stove from the 1970's and 1980's averaged around 20 - 25% efficiency, while current EPA approved stoves range from 75% to as high as 90% efficient. This equates to burning less wood to get the same amount of heat.

An EPA certified wood stove can be identified by a permanent metal label affixed to the back or side of the wood stove.

Zone Heating vs. Central Heating

Zone heating is putting the heat where you need it most versus central heating systems which can distribute heat to the whole house. Zone heating with a space heater such as a wood ( or gas or pellet) stove, fireplace or fireplace insert can save the homeowner significantly on their overall heating bills.

Zone heating creates a cozy warm area for the family to gather allowing the central heating system to be set lower. The zone that one can heat with a space heater is determined by the design of the home. The more open the house plan, the larger area (zone) one can heat with a new heating appliance. Why heat every nook and cranny when you are not using that part of the house?

Zone heating is direct heat. The duct systems of most central heating systems have significant heat loss before getting the heat to the livaing areas. Thye longer the run of the heating ducts, the greater the loss.

Location of Your Stove

First, the area selected to install a new stove may be limited to the location of the existing venting system or by factors like obstructions above the installation that precludes installing a new chimney system.

Second to consider is the area that one wishes to heat. Stoves are space heaters, sometimes referred to as zone heaters.

For maximum enjoyment and heating effectiveness, install your new wood stove in a major living area where the family spends leisure hours and which provides heat flow to other areas is usually a strongly preferred location for the stove.

A third consideration is the space requirements. Wood stove installations must meet minimum clearances between the stove and nearby combustible surfaces plus the hearth or floor protection must extend beyond the front and all sides of the stove. These requirements are clearly stated in the owner's instruction manuals. Local codes must also be followed.

Why does the glass on my wood stove soot up?

Soot will appear on the glass if the firebox temperature is low or if the lighting off period is too short.

When first firing the stove a lot of combustion air must be supplied to establish a good fire and warm up the chimney. Open the air controls.

Once the kindling fire is well established dry wood can be added. The combustion is then controlled by the primary air control.

Wet or green (unseasoned) wood or poor draft conditions might also cause sooty glass. Ask your Chimney sweep to measure the draft in your chimney.

Floor Protection

Yes, wood stoves require a hearth or stove pad unless installed on a concrete slab. Some wood burning only require ember protection while others need thermal protection.

Many stoves supply (sometimes as an option) a bottom heat shield that reflects the heat away from the hearth. The bottom heat shield is then usually required unless the product is installed on the foundation level. . Always check the manufacturers installation requirements for values and minimum size before installing your wood stove and install according to the stove manufacturer's instructions.

Poor Draft

All text from Jotul North America

The main function of a chimney is to create draft for combustion and to transport the flue gases out of the building.

A good draft is vital for a good combustion. We consider a normally good draft to be between 10-20 Pa (1-2 mm VC). The chimney creates the draft, not the appliance.

Essential for the draft is the construction of the chimney

A tall chimney gives more draft. If the draft is insufficient it can be a solution to build a taller chimney. The chimney diameter should never be less than the diameter on the appliance flue outlet. A circular chimney liner normally gives a better draft than a square. Use of flue pipe elbows reduces the draft.

If elbows are used it is better to install with 2 X 45o instead of a 90o.

Combustion air is essential for the draft

An open fireplace requires approx 300m3 air each hr, while a “closed” fireplace requires approx 30m3 per hr. A kitchen duct / ventilator sucks much more air than a chimney. This will create a negative draft. Negative chimney draft causes smoke in the room.

Influence of the wind

Draft disturbance can be caused by tall trees, cliffs or tall buildings. The problem can normally be solved by making the chimney taller.

Draft is simply hot air rising

High temperature creates strong chimney draft. A good result is achieved when the height and diameter of the chimney fits the appliance. Too strong a draft can cause the heat to be sucked too fast into the chimney. Too strong a draft can be regulated with a damper, draft regulators (flue pipes or chimneys), or restrictors.

  • Wood quality: Wood with a lot of moisture can cause more smoke than the chimney can dispose of.
  • Air systems like air condition, bathroom or kitchen fans might take their need of air from the chimney (negative draft)
  • Operating errors: Always open the damper and primary air control before you reload the stove - open the door slowly.
  • Flue pipes: Remember that elbows (90o) and long horizontal flue pipes make restrictions on the draft.
  • A chimney that is too short could give insufficient draft for the fireplace.
  • A chimney that is too cold can cause none - or negative draft. Flue liner must be correctly connected to the fireplace and the chimney - and have the right dimension.
  • Blocked chimney could be caused by a birds nest, soot, or tar.