How burners control output
| Type | How it works | Where it is used |
|---|---|---|
| Single-stage | Full output or off | Small boilers with steady load |
| Two-stage | Two fixed outputs: low and high | Boiler houses with moderately varying load |
| Progressive | Two stages with a smooth transition between them | A compromise between staged and modulating |
| Modulating | Smoothly varies output within its range based on a sensor signal | Boiler houses with variable load, industry |
Two-stage: simple and reliable
At low load the burner runs on the first stage, at high load it adds the second. Advantages: simple controls, low price, easy commissioning. Drawback: output changes in steps — when the load lies between stages, the burner switches or shuts down often and the temperature fluctuates.
Modulating: precise and economical
A servomotor smoothly adjusts fuel and air, and a controller holds the set temperature or pressure. The key parameter is the turndown ratio, for example 1:3 or 1:5: the wider it is, the lower the load at which the burner still runs without stopping.
Advantages: fewer starts and stops, steady temperature, lower fuel consumption and longer boiler life. Drawbacks: higher price, more complex controls and skilled commissioning.
What to choose
- Load is nearly constant — a two-stage burner is enough.
- Load varies widely over the day and season — a modulating burner pays back through fuel savings and less wear.
- The process needs precise temperature or steam pressure — modulating.
- Strict emission limits — look at low-NOx burners; they come in both two-stage and modulating versions.
We will select a burner for your boiler, fuel and load profile.
Boiler equipmentFAQ
Does a modulating burner save fuel?
What does a 1:5 turndown ratio mean?
Can a two-stage burner be replaced with a modulating one?
How does a progressive burner differ from a modulating one?
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