Masonry Heater Fireplace

The Masonry Heater Fireplace - How it Works & How to Start it

This house has a masonry heater which, until you take the time to learn a little about them, as well as how to use them, it’s hard to appreciate just how fantastic they are. The masonry heater burns wood. The beauty of it is that you can load it up with a lot of wood, all at once. The fireplaces are designed to take it and they count on you doing it this way. After the firewood is reduced to coals you can shut the vent to the outside, trapping the heat to be absorbed by the rocks.

The shut-off vent at the top has a hole in it so you can’t shut off the fireplace completely for safety reasons. The path the heat takes inside the fireplace before it exits out the flu resembles a labyrinth so that all of the intense heat is absorbed by the stones before leaving the fireplace. By the time the heat gets out of the fireplace and up the flu, the temps are between 350 F – 450 F according to the Cold Climate Housing Research Center located in Fairbanks Alaska.

You only need to start the fire or load it about 1 – 3 times in a day, at least at this house. You can get away with loading it one time in a day as long as it’s still warm from the night before. If the rocks has still retained a lot of the heat, it’s just a matter of loading the heater up again, waiting for low-to-no flames, and shutting the upper and lower vents. You leave the vents shut until it seems as though the rocks have peaked and are starting to cool off. Depending on what time of day this is, you’d add more wood.

The bottom line is that the rocks or stones absorb or captures the heat as the heat travels through the labyrinth type maze to get up the flu. It takes about 6 hours for this fireplace for the rocks to get very hot. That might take 3 loads of wood and going through the procedure of seeing the low-to-no flames and shutting the vents.

You might just get so involved with the process that you’ll be “bummed” when summer comes. Well . . . maybe you’ll just have to hike up South Sisters to cure yourself of the “bummers”.

Our Masonry Heater

Website Links & Some Pics

Two Quick Videos to Educate You on What a Masonry Heater is and How to Use it

Website Links & Some Pics

Here are a few links to some of the experts in cold climate research and masonry heaters. The Cold Climate Housing Research Center is located in Fairbanks, Alaska while the Masonry Heater Association of North America is located in Tucson, Arizona. If you haven’t visited our Strawbale Insulation Page to learn about the insulation factor, be sure and check it out. If you’d like to read about just what strawbale construction is, visit our What’s Strawbale Page  Keeping the house cool in summer and warm in winter is the job of strawbale insulation.

I’m writing this on December 25, 2017 and when I got up this morning it was 10 deg F outside while our inside temp registered 58 deg F. When we run the fireplace, we turn off the heat for the downstairs zones and last night, I stopped adding wood at 4 pm and at 6:30 pm, closed the vent to keep the heat in the masonry heater. Even though it was 10 deg F outside this morning and it registered 61 deg F when we went to bed, it only lost 3 deg F overnight. That’s the power of strawbale and the masonry heater working together.

Watching the videos to correctly use the masonry heater is imperative. The heater can get hot and if you keep throwing wood in, it will most certainly keep burning. You should build up the fire, then, as it burns down you slowly close off the vents until there are low-to-no flames and then you should have the vents fully closed. Like the video mentions; there’s a hole in the upper vent so that you can never fully close off the vent. You want to keep the heat in the fireplace so that the rocks absorb the heat and then transfer it into your house. At first, the rocks won’t feel very hot but after about 4-6 hours, you won’t be able to leave your hand on the rocks.

You want to build the fire up and then let it burn down, closing the vents until you see no more coals, almost like the fire’s completely out. Then, you build up the fire again going through the same procedure. If we do this in this masonry heater between 1-3 times, it will heat the downstairs and partial upstairs through the night and into the late morning.

weather app at 10 deg F

Below Are Some Graphics For Masonry Heaters & How They Work

Masonry heater drawing
masonry heater explained in drawings
masonry heater features explained in a picture