The main thing that distinguishes a masonry heater is the ability to store a large amount of heat. This means that you can rapidly burn a large charge of wood without overheating your house. The heat is stored in the masonry thermal mass, and then slowly radiates into your house for the next 18 to 24 hours.

If you burn wood fairly rapidly, it is a clean fuel. If you try to burn it too slowly, the fire will change from flaming to smoldering combustion. The burning process is incomplete and produces tars. Atmospheric pollution increases dramatically. This is important if you are planning an energy-efficient house. The average energy demand of your house will be quite low. For most of the time, it may require only 1 to 2 kW of heat. For most conventional woodstoves, this is below their “critical burn rate”, or the point where they start to smolder.

Masonry heaters fill the bill perfectly. If you need even a very small amount of heat, such as between seasons when you simply want to take off the chill, you simply burn a smaller fuel charge–yet you still burn it quickly. The large surface is never too hot to touch. You have a premium radiant heating system with a comfort level that simply cannot be equaled by convection or forced air systems.

Common Questions About Mansonry Heaters:

Do Masonry Heaters have fans to circulate the heat?
No - Masonry Heaters are radiant heaters. As in floor radiant heat or as in an older building that had hot water radiant heaters spaced around the home or office - no fans needed. Actually, a fan would cool the area as a fan would cool you on a hot sunny day.

What makes a Masonry Heater work?
The Masonry Heater consists of a firebox and a lambrith of flue(heat exchange) channels. The flue gasses serpentine through these channels giving off heat to the masonry before reaching the exit flue. After the fire is out and the damper is closed, the masonry mass gives off this captured and stored heat to the living space needing heat.

What if it gets too hot?
No problem. A heater cools slower in a warm environment and faster when it is cool. So if the heated space reaches 75 degrees or more, the heater does not cool as fast as if the space was 65 degrees. If that happens, you would skip the next one or two scheduled firings. Also, you could open windows for some nice fresh air or turn a fan on to chill the air. This is not a problem.

Do Masonry Heaters have a catalytic converter?
No - catalytic converters work on wood stoves where there is no mass. The catalytic converter is actually a miniature masonry mass that increases the flue temperatures for more complete combustion. In Masonry Heaters the entire structure is a heat storing masonry mass, so the temperature is high enough for a complete burn. Tested Masonry Heaters on an average burn cleaner than all wood stoves - even those equipped with catalytic converters and second only to pellet stoves.

What kind of wood do you burn in Masonry Heaters ?
You can burn any wood properly dried to less than 20 percent moisture and split to proper size in your Masonry Heater. Size depends upon the heater design - ask your heater designer. Usually two to three inches in diameter minimum to five to six inches maximum.

How much wood does a Masonry Heater burn?
That depends on the model. Smaller heaters can heat 1000 sq. ft. with 15 pounds of wood two times daily for a total of one cord per season in Western WA. A medium heater could heat 1500 to 1800 sq. ft. with a 30 pound load two times daily for a total of two cords per season. A heavy duty heater could heat 2200 to 2800 sq. ft. using 45 pounds two times a day for a total of three cords per season. The first year, most people use 30 to 50 percent more wood than is needed and with time learn how much fuel to use for their needs. New heaters for the first season use more fuel because moisture in the heater uses some of the heat energy. Also, new homes have a higher moisture content and need more heat to feel comfortable.

Why do Masonry Heater cost so much?
Consider a Masonry Heater an investment compared to a masonry fireplace. True, they cost $4,000 to $5,000 more than a fireplace. However, a masonry fireplace is at best 10 percent efficient, where a Masonry Heater exceeds 60 percent efficiency and up to 80 percent. Part of the cost assures performance. Masonry Heaters are complex and we use more materials, higher quality materials and more than twice as much labor to construct as a comparable size fireplace. The original cost is greater, but the added value and heating convenience and resale value is always greater than the original cost.

What are the drawbacks to a Masonry Heater?
1. To some people it is the cost.

2. To others, it is the delay in heat output versus fueling cycle. Masonry Heaters unlike other heat sources need to be recharged (fired) on a 12 or 24 hour cycle. Today's fire is tomorrow's heat. The fire lasts about 2 hours every 12 hours.

3. To most, it is the short fires - not enough time to enjoy the aesthetics.

What are the benefits?
1. Easy to use, convenient, low tech and it works.
2.Clean heat for people with allergies or asthma etc. - no indoor pollution.
3. Low cost quality heat and efficient.
4. No power needed to maximize heat output.
5. Safe, never too hot to touch, except the metal or glass doors when the fire is burning.
6. Can be custom designed to your needs.
7. Can be custom designed to any decor.
8. Value added for resale and aesthetics.
9. No utility bill - uses renewable fuel.
10. Good for the environment. Does not add to the greenhouse effect.
11. Exempt from EPA, Certified in WA, CO, MN and other controlled air sheds.
12. Reliable old technology proven in Europe over 300 years ago. (Not an unproved theory.)
13. Standard model core kits can be installed by any quality mason.
14. Low maintenance. Yearly inspection minimum, but if properly used the cleaning cycle may be needed only every two or three years.
15. Unlike other heater sources, bakeovens and heated benches (hearth) are common in Masonry Heaters.

© Duxbury Chimney Sweep, Inc. All rights reserved.