Meridian Masonry Heaters

FAQ

What is a masonry heater?

A masonry heater allows wood to be burned for home heating in a unique way. It’s main distinction is the ability to store a large amount of heat. This means that you can rapidly burn a large charge of wood without overheating the house. The heat is stored in the masonry thermal mass, and then slowly radiates into your house for the next 18 to 24 hours.This results in a number of benefits. If you burn wood fairly rapidly, it is a clean fuel. It has a low ash content and almost no sulfur content. If you try to burn it too slowly, however, the fire will change from flaming to smoldering combustion. The burning process is incomplete and produces tars. Atmospheric pollution increases dramatically. The ratio of emissions between complete and incomplete combustion with wood can be as high as 100 to 1.

These characteristics of wood combustion become very important if we are planning a wood fired heating system for an energy efficient house. The average energy demand of this newer type of house is often 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. In other words, wood burning and energy efficient houses don’t really suit each other very well, unless you have some way to store heat so that your stove can operate in the “clean” range all of the time.

Masonry heaters fill the bill very well. 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 is second to none.

What is the Brief History of Fireplaces

The first controlled use of fire by man predates our own species, and is now believed to have occurred 1.4 million years ago by Homo erectus. Agriculture, in contrast, is only about 10,000 years old. Although chimneys were known in Han China 2,000 years ago, they only came into general use among our British forebears around the sixteenth century. Interestingly, of the northern European cultures only the British and French have an open fireplace tradition. Since our North American heritage is mainly British and French, we share this tradition. Not surprisingly people in both countries, peasant and nobleman alike, used to basically freeze in the winter. In our harsh North American climate, the open fireplace was replaced for primary heating by the closed combustion iron stove in the 18th century. The open fireplace is commonly found to this day as a main heat source in the milder climate of the British Isles.

We still carry this ancient relationship with fire in our consciousness, even though few people are still aware that the words “hearth” and “heart” share a common origin. 

·         What is the main difference between a Meridian Freestanding "Stove" and a "Masonry Heater"?  A Meridian Masonry Heater is larger than a Meridian Stove.  Both function much the same and have very similar double wall construction that allows both convective air circulation and radiant heat.

·         What is the term "Heat Storage"?

Heat storage is the main feature that distinguishes masonry heaters from woodstoves and fireplaces. It is

the key element that allows a fast burn rate, thus simultaneously optimizing wood combustion yet not

overheating the heated space. This is a key point and cannot be overempathized. A high heat release rate

in the firebox accompanies the high burn rate, but because of a limited loading door size and internal flue

gas heat exchange channels, only a fraction of the available heat is released to the space during the burn.

·         What is the Intended Use and Location

A masonry heater is a serious heating appliance, not just a decorative architectural element in the house.

Because it is a radiant heating system, location is important. Central location is best. If it is located on an

outside wall, it must not penetrate the insulated house envelope.

Any masonry appliance that penetrates the house envelope, as is typical for conventional masonry fireplace,

should be defined as not being a masonry heater. The Canadian R-2000 regulation for masonry

heaters (see Appendix) goes one step farther by prohibiting the use of outside chimneys.

·         What is an EPA Exemption?         

since masonry heaters do not suppress combustion air flow, they cannot be turned down to achieve the low burn rates required by

EPA and might exceed the maximum EPA firing rate

of 5 kg/h, depending on how the burn cycle is interpreted.

·        What is the difference between Masonry Heaters and a Meridian Masonry

o       Masonry Heaters are 100% radiant heaters where MM is approximately 50% 50% radiant and convective heaters.  Therefore they circulate heat throughout  the room(s) as well as just local radiation.

o       Lessens the outside wall temperature for closer wall clearance.

o       Double wall construction.