Turtlerock Masonry Heat
Information Interior Finishes
Heaters Metalwork Design
Living with Masonry Heat Heater Firing Planning Guide Performance Guide
About Us
Download PDF

Life with a masonry heater as the primary heat source.

Once the heater is built, the new owners have arrived at the beginning of a long and fruitful relationship. For some, the use of cordwood for home heating may be a familiar experience. For others, the routine is new and may require some getting used to. Either way, the experience of keeping a heater in daily operation is for most a ritual that is learned and eventually perfected.

If the owner has been used to turning the dial of a thermostat for their heat, then a heater will require a bit more effort to operate. On the other hand, if the owner has been regularly feeding a conventional wood stove and consuming large amounts of fuel, then the heater is seen as an easing of the daily work load.

Every new heater requires an initial break-in period, where it is slowly fired to allow moisture to escape and all masonry to cure. Following the break in, the heater is ready for everyday use.

Daily Use of the Heater.

Every heater has a designed fuel load and firing cycle. These variables are unique for every project and are factors of heater size and heating requirements for the environment in which it is placed. Most fuel loads are in the range of 30-60 pounds of 16” hardwood cordwood, cured to 20% moisture content. Firings are completed in 12, 18, or 24 hour cycles most commonly, with a typical maximum firing cycle of every 8 hours. In normal operation, most heaters are fired twice daily at or about the maximum fuel load during coldest months.

Most families will fire their heater once in the morning, soon after waking up and as part of the daily ritual of “the morning routine”. If everyone needs to leave the house for the day, the heater must be fired early enough so that combustion is completed before leaving, and the dampers can be closed. Most burn times range from 1.5 hours to 2 hours.

The second firing is then lit in the evening. For folks working in the 9-5 mold, this may mean firing the heater as you return home and settle in for the evening. Again the firing should be timed so that the dampers will be closed before all have gone to bed.

If the heater has a bake oven, and the owner intends to use the oven for the evening meal, the firing will be timed so that the oven will be at optimum temperatures during the desired cooking period.

Once the fire is laid and lit, it will normally require very little tending once efficient combustion is established. It helps to rake the coals towards the grate to speed up the last phase of the the burn, but that is all that is needed.

Every new user experiences the “learning curve” during the first winter with their heater, but in time the firing process becomes comfortable and is seen as a regular, repeatable event.

Wood Pile
The Wood Pile

Hardwood cordwood is the best fuel, especially if it has been cured properly. As a rule of thumb, it should be cut, split, stacked and covered for a minimum of nine months before use. The ends should be checked and the sticks of wood should ring when hit together. Green wood should not be used, so it’s best to take the fuel supply seriously to make sure adequate amounts for the winter will be available. Most heaters in daily use will consume between 2-4 cords over a heating season. The diagnosis of most heater performance issues starts with an analysis of the fire wood quality.

Laying the fire
Laying the fire
Laying the next fire in the firebox is the everyday task that fuels the heater. All the fuel for the burn is loaded into the firebox before the fire is lit. There are several ways to stack the wood in the firebox, and most people generally settle in on what works for them after some experience. Once the wood, paper and kindling are readied, the laying and lighting of the fire requires less than 5 minutes.

Charlotte Heater
Most heaters in daily use will have trouble free start-ups. A single match touched to the newspaper is sufficient. The burn is robust- combustion temperatures at their highest point can reach 1800 F. Masonry heaters burn very clean, with little particulate emmissions. Once the fire is laid and lit, it requires little tending on its way to completion, when the dampers are closed.

The Bake Oven
Bake Oven

Bake ovens are a commonly installed option that adds an extra function to the heater.

The oven can be used in many ways, and often is customized for the owner depending upon user preferences. Ovens do not deter from the efficiency of the heater, and usually fit into the overall design schematic with some ease. The oven temperatures will follow the firing cycle of the heater, reaching maximum baking temperatures around the end of the burn. At this point the oven is best for pizzas, and will be normally 450 F to 525 F. In time, the oven will begin to cool and come to a good bread baking temperature. As time passes, the hearth will cool further, and the oven will be perfect for braising and slow cooking. During the lower temperature phase, lidded heavy cast iron and crock pots do very well for soups, stews, and meats cooked over the course of hours.

Another advantage of the oven is that the owner will always have a “hot spot” for food without using another source of energy (as long as the heater is being fired). Using the masonry heater to cook as well as heat makes the heater even more efficient. In the event of an extended power outage, the owner has a way to cook independent of electricity.

The design of the modern floor plan is more open, and the placement of the masonry heater on the first floor and as a rough divider between kitchen and living areas is common. In this manner the bake oven would typically be placed on the kitchen side of the room. The added function of the bake oven makes the heater more utilitarian, more tactile, and more a usable facet of the living environment.

Domestic Hot Water Heating Coils
Heating Coils
Domestic hot water may be created by the masonry heater.

Water may be heated for domestic use through the installation of a stainless steel water coil into the core of the masonry heater (shown in firebox above). Normally this is done with high pressure Schedule 40 stainless steel pipe, from 3/4” to 1” in diameter. The pipe makes a loop in the firebox and exits out of the side of the heater, where the in-flowing and out-flowing water are plumbed in. These systems are commonly designed using the thermosyphon method, where the flow through the water coil is naturally regulated by the firing of the heater. The water is then stored in a hot water storage tank and used for regular household purposed (bathing, laundry, etc). A benefit of the thermosyphon method is that it is not dependent on electricity.

Other methods and schematics may require circulation pumps, and direct the heated water towards storage tanks and then onward for hydronic heating systems, etc. The use of circulation pumps allows greater flexibility in design and use of heated water, but may limit the use of the heater in times of power outage. All plumbing should be conducted by experienced plumbers only.

While the use of hot water heating coils extends the use of the heater into domestic hot water production, it is wise to remember that it likely does not increase the efficiency of the heater or boost total BTU output. In simple terms, the energy output of the designed fuel load will remain the same- when a water coil is present some of the energy (produced by combustion of the fuel) will be put into the water and not the masonry (the main heat storage component of a masonry heater).


turtle logo