Properly size a pellet boiler

Share this article with your friends:

Heating with wood pellets: the question to ask before choosing this method of heating?

How to properly size its future wood boiler?

The average power of the boiler must correspond to average losses of his house when it's coldest. Estimating losses, ie make a heat balance, so finding the right power of his boiler.

The best way to properly size is to do a study or heat loss from the slot. In some areas, this study is subsidized.

a) Make a complete thermal study

Doing a reliable study is not necessarily obvious. Some sites on the internet allow to make approximations with as input, the place of residence, the general characteristics of the house ... See "Learn more" below.

Spending a few hours to test multiple sites and / or method is a pretty good way to have a consistent trend.

b) Use the ancient power of his boiler

If boiler change take power equivalent may be tempting but it's not necessarily the right solution because:
- Former heaters are often oversized
- As we have seen previously: the oversizing of a wood boiler can be catastrophic in terms of performance
- A more powerful boiler is more expensive
- Improvement works (insulation, changing frame ... etc) may have been made in the house: the needs are less important than before.
- Climate change: in many region, winters are milder in a decade. bases temperatures heat balances calculations are therefore may be, again ...

3) Approximation by volume

A very simple but also very imprecise method is to use a first approximation the volume of your home.

We can also multiply the volume occupied by 30W / m3 (well insulated) to 50W / m3 (poorly insulated) but the margin of error is large and oversizing of your boiler is possible with the problems this creates.

Note if additional heating

If you have a booster heater style fireplace or stove, and you make a complete calculation from the base temperature in your area, think back the last few degrees or integrate the power provided by the fireplace in the calculation.

If he -15 ° C once every 10 years, and that the boiler is not powerful enough that day, you'll make a fireplace and more.


Properly size the wood boiler is paramount, even more than oil or gas.

Heating the professionals are not necessarily the most competent to make a heat balance and, commercially, some will tend to offer you more powerful hardware because more expensive.

So do not hesitate to call a thermal design office: the cost of the study of the thermal balance will pay for itself tenfold if it saves you from buying a more powerful boiler, so oversized.

You can also use the heat balance tools we put at your disposal.


- Make a heat balance or an energy audit
- Thermal balance and DPE by ADEME
- woodburning Forum
- Downloads home, insulation and heating

Read more: estimation calculating consumption of pellets

Previous article: Problem of the design of a wood boiler


Leave a comment

Your email address will not be published. Required fields are marked with *