What is a heat storage stove?

Wood burning stoves have always involved an element of heat storage which was derived from their traditional cast iron construction. What the early stove makers discovered was, that not only is cast iron strong enough to take the intense heat from the stove's fire chamber, but that the thermal mass of cast iron also delivers heat long after the stove has gone out. It's one of the great benefits of traditionally made stoves which, to some extent, has been diminished over the generations because of the changing methods of stove construction and also our reliance on central heating to provide convenient background heat in our homes. However, the ever-increasing cost of energy, much better house insulation and environmental concerns have encouraged a re-appraisal of the benefits that heat storage from wood burning stoves could bring to the modern home. 

Consequently over the last few years in Europe, particularly Germany and Denmark, heat storage stoves have been enjoying a renaissance. Cutting edge Scandinavian stove brands like Hwam with their 7150M Soapstone model, which is not only highly practical but also simply stunning, and Stuv with their Stuv 30 Compact High – one of the highest efficiency stoves we have ever seen, have produced some beautiful heating solutions with the emphasis on heat storage. There are two basic types of heat storage stoves – those featuring stone panelling (usually soapstone) where the body and lid of the stove is clad to form a heavy heat sink and those strikingly tall stoves where the heat storage elements are concealed in their own compartment above the fire chamber.

So what are the advantages of a heat storage stove? Well, let's get one myth out of the way first: the heat storage elements (soapstone, stone, ceramic etc) don't make the stove more efficient. That is, they don't make it produce more heat for the same amount of fuel burned, but they do however provide a kind of 'time-delay' to the delivery of that stored heat from the 'charged' heat storage elements. Heat storage stoves essentially smooth out the peaks and troughs of the traditional stove's heating curve during the heating cycles. 

As we know, a big fire equals more heat. As the fire dies down though it produces less heat until the fuel is then re-loaded when more heat is again created. This produces a heating curve with distinct peaks and troughs. With a heat storage stove once the heat sink is 'charged' it delivers a fairly constant heat throughout the cycle, which when combined with the traditional cycle helps fill in those troughs to produce a more even heat. Additionally, when the stove eventually does go out the charged heat sink continues to deliver its stored heat for many hours afterwards. In a well insulated house, where a little heat will go a long way, this a heat storage stove can be a cost-effective means of maintaining a higher ambient temperature in the home over a much longer period.

Pictured below is the powerfu,l German-made, Max Blank Stratos M with its brushed slate natural stone heat storage panels. You can you see this stove, along with models from Hwam and Stuv, in The Stove Yard's Newtownards showroom.