Log Burning - free standing vs cassette


Dear John,

We read your article for the first time last week and found it very interesting and thought you may be able to help us in our predicament. Last summer we moved to Spain having bought a really nice villa in Calpe. The property is on a north facing hillside and although the views are fantastic we did feel cold last winter. We would like to install a wood burning fire but have heard differing stories, good and bad about stand alone and cassette fires; can you clarify the difference between them, and the advantages and disadvantages of each type.

Kind regards.

David & Linda Cooper

Hi David and Linda,

Your question comes at a very appropriate time of the year; after a very hot summer people are turning their thoughts to the chilly winter ahead and how they are going to keep warm. There is certainly something very relaxing about the flickering flames of a natural fire and if installed correctly both types will produce a tremendous amount of heat. There is a great deal of confusion about wood burning fires, their operation and relative merits, this question is probably best dealt with by describing each fire and then drawing some conclusions.

Stand alone fires.
As the title defines the fire stands on its own and as such requires no additional energy to operate. The efficiency with which it heats is determined by its size, design and the amount and quality of wood loaded into the unit. Most good quality modern fires have excellent outputs for their size, burning with an efficiency of 70 to 80% and ranging in size from 3kw to 29kw with the capability to run a central heating system of up to 15 radiators.
With a stand alone fire the fires casing simply heats up, radiating and conducting heat directly to the environment. This leads to the most common mistake made when installing this type of fire. It can  be appreciated if this type of fire were to be placed in a fire place recess not much larger than the fire itself, most of the fires output is used in heating the surrounding masonry rather than heating the room.
A stand alone fire must stand alone or at least be sited in a fire place recess that is substantially larger than the fire itself with good air circulation around the unit. Enclosing a freestanding fire is a very common and fundamental error.  

Cassette fires
The cassette fire as the name suggests fits like a cassette into the correct size space in a fireplace. It is usually constructed of two casings, an inner and an outer. The outer is usually a lighter metal plate surrounding a heavier inner casing in which the fire burns. The air (3cm-6cm) space between the two casings is heated and circulated into the room by fans in the unit. These fans may be thermostatically operated, switching on and off with the temperature of the fire, or manually operated. Thermostatic fans can be very annoying, switching on and off as the temperature fluctuates; manually controlled fans are recommended by people in the know. Some fans can be very noisy but quality fires have fans with an acoustic level similar to a hair dryer on low speed.
Given that the fans are electrically powered and in certain areas of the country the electricity supply is most unreliable one could be looking at a fiercely burning fire with no heat in the room because the electrical supply is off.
Purists would say that using electricity to circulate heat from a wood fire does fly a little in face of an environmental friendly heating system.
Heat outputs of these fire range between 5kw to 22kw with a burning efficiency of 70 to 80 %.

When constructing a new house, with no restrictions and no preference on design the freestanding fire is probably the most efficient and cost effective means of heating the living spaces and some very large spaces can be heated using these units.
Cassette fires, although effective in heating spaces tend to be more expensive and always require a fire place to be constructed in which to place the fire.
Although the freestanding fire may be considered more effective, it eventually comes down to personal choice.

As I mentioned in a past article regarding Spanish chimneys that you really need to get it right the first time. I suggest that before you decide anything you contact a reputable specialist company, the only one I recommend is Meridian Stoves at the side of the petrol station in Jalon, they have a good selection of freestanding fires and quality cassette fires to look at and I have always found them to be very helpful and knowledgeable on this subject.
I hope this is of help, please let me know how you get on and I hope you’re warmer this winter.

John Phillips (F.I.A.S. F.A.B.E. M.I.B.C.O. F.F.B. M.R.S.H. C.M.W.O.B.O. M.B.I.M)
Construction Buena Vista

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Urb. Palmeria. Orba 03790


Please call us on


0034 965 577 464 (office)


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