Building an Original Masonry Heater - Made-to-Measure Plans with Bench, Combination Oven and Log Store

At the end of 2010, a client contacted us to build his masonry heater as a partial self-build.

Located in Saône-et-Loire (71), the masonry heater is to serve as the main heating for their house, which was under construction.

A Project Built Around a New Greb-Type House

This project revolves around a new Greb-type house. We therefore needed a heavy heater (with a brick firebox) in a central position, as the house has little thermal mass apart from the external walls. We therefore opted for a firebox taking around fifteen kilos of wood, with a log store and a heated bench. Once the energy requirement of the house had been calculated and the plans drawn up, we started work!

Design plans:

Insulating the Area and Positioning the Heater:

First of all, it is important to insulate the area where the heater will stand with a base, here made of aerated concrete.

Aerated concrete does not like high temperatures, and to bring the height up to finished floor level, we cover it with hollow clay bricks on which we start laying the first course of firebricks with 30% alumina (made in Alsace).

Flue Gas Path and Second Course of Bricks:

On this base, we build the flue gas circuit, taking care to leave openings so that we can later fit the cleaning doors, also made of refractory material. The bench flue gas circuit gradually narrows to keep a constant gas velocity.

Next, we lay a flat course of refractory slabs and firebricks, leaving a space at the side to allow the flue gases to circulate (on the left of the picture downwards, then towards the bench - on the right from the bench towards the outlet at the top).

Building the Combustion Chamber:

Construction of the combustion chamber begins with an angled cut, giving a large ash pit with a deliberately reduced area for the ash grate.

The bio-soluble refractory blanket , formerly called ceramic blanket, accommodates expansion.

Building the vault:

The vault is made from refractory arch bricks : we used sand spread over a wooden board placed above the firebox to make laying the bricks easier and, in particular, to keep the semicircular shape of the top of the oven. The vaults are then covered with a refractory castable to ensure their stability, as there is little material at the sides to hold them in place.

The combination oven:

The oven is then built, giving it the same shape as the combustion chamber with its vault. Its special feature is a refractory door on the left-hand side allowing a fire to be lit directly in the oven. The flue gases from the oven then pass through the open door and go straight to the end of the circuit. Ideal for grilling sausages in winter without filling the room with smoke, or for lighting a fire directly in the oven so as not to heat the whole heater in summer, for example.

Dampers and flue gas circulation:

Installation of the bypass damper (short circuit), with an access allowing a fire to be lit directly in the oven. The damper allows switching to a short circuit and therefore avoids having to heat the whole storage mass to cook your dishes. Once winter is over, it is always pleasant to be able to use your masonry oven without having to heat the stove and therefore the house. See the products available in the "dampers" category.

Closing the masonry heater:

The top of the heater is closed with refractory slabs, some of which are bevelled at 45° to support their neighbours.

Cladding brick layer and finishing render:

The cladding was carried out by the customer, with whom we shared our techniques and advice to ensure it was done properly.

To sum up, it is entirely possible to treat yourself to a masonry heater even on a tight budget!
We do everything we can to make your project happen and will adapt as best we can to offer you the most suitable solution!

For projects with more support from us ("turnkey" or partial assistance by the customer ...), please visit: www.thermasse.fr in the section "Etude de projet" (Project study).

We will be delighted to give you advice and answers!