The standard NF D35-376 power of a wood stove

How is the power of a wood stove defined according to standard NF D35-376?

For any suggestions or remarks: definitions of the power and efficiency of a wood stove

The reader will carefully read the introduction to this “wood heating” dossier: why choose firewoodFor any questions on wood heating, see our forum heating and insulation.

Unlike appliances using fossil fuels (where the power depends directly on the fuel flow which is easily defined), the power of wood-burning appliances, especially with logs or briquettes, is difficult to "feel" because the power of a fire. wood is not at all constant. It goes through a maximum. The power curve of a non-automated wood burning appliance resembles a Gaussian curve well known to statisticians.

With automated pellet machines in which the flow of pellets is regulated, the problem arises less. We are almost in the case of a fossil fuel device.

Should we talk about average power, maximum power, power after X hours?

This article, outcome of this discussion answers them according to the elements of answers found on the site of a French manufacturer: Deville.

Definition of the nominal power of a wood-burning appliance

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Certain commercial advertisements referring to maximum or instantaneous powers can deceive the purchaser of a hearth or an insert since these powers have only a very ephemeral character.

The only power ad complies with standard NF D 35376 (standard for all timber and coal fireplaces inserts) is the nominal power.

This nominal power is the real power obtained by the user under normal conditions of use and this nominal power is the only one which makes it possible to meet the users' needs.

We notice the power differences between the “nominal” and “maximum” powers, which can, if necessary, cause great dissatisfaction among the user who in fact relied on an “illusory” power. "

rated power wood heating

Examples of maximum and nominal powers of various non-automated wood-burning appliances and example of the evolution of a power curve over time.

It is easy to notice through this typical operating curve of a fireplace or an insert that the maximum power obtained can reach 250% (2.5 times) of the nominal value announced, i.e. for a device with a nominal power of 10 kW, a maximum power of 25 kW (obtained in a very short time).

This curve also proves that the power returned to the home, and therefore to the user, is an average calculated according to the standard over a period of approximately 3 hours.

The NF-D35 376: 2 indication of powers

To choose a wood-burning appliance is to choose an appliance with sufficient power in nominal power of course.

Check and ask the manufacturer, seller or installer for the 2 powers: a consistent answer is a guarantee of quality of service.

Manufacturers taking into account this difference, a nameplate on each device indicates its rated power and its specifications.

For any suggestions or remarks: definitions of the power and efficiency of a wood stove

Links to learn more

1) The choice of material:

- How to correctly choose a heater with wood? (Stove, boiler or boiler)
- List of stoves and boilers labeled "Green Flame"
- Help and advice for choosing a wood stove
- Choose the power of his wood stove
- The normalized power heaters Wood
- Choosing a wood boiler

Read also:  Drying of firewood according to air humidity

2 Heating with wood every day: maintenance and improvements:

- The different types and prices of firewood fuel
- Heating and wood fireplace: How to avoid chimney fires. Maintenance and dimensions
- Regulation about the chimneys, the standards and the law
- Make a hot water collector on a wood stove
- The manufacture of pellets: diagram of a factory

3) The pollution of wood heating:

- Wood heating and pollution on health
- wood heating pollution
- Atmospheric emissions of firewood and biomass energy

4) Feedback from wood heating experiences:

- Complete file on the presentation of a pellet boiler installation at a private home
- Presentation and photos of another pellet boiler installation in Alsace at a private home
- Presentation of a wooden and solar house
- Auto installation of our wood boiler Deom Turbo explanations and mounting scheme
- effective yield estimate of our stove Boiler Turbo Deom
- Forum wood heating and insulation

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