11 Low-emission operation
Notes on complying with limit values in Germany
after 1 January 2015
In accordance with the provisions of "BImSchV," lower
limit values for the emission measurement in Germany
apply to all new heating system installations starting
1 January 2015. In particular, compliance with the new
dust limit value of 20 mg/m³ can lead to problems in
practice.
It was determined under laboratory conditions in
testing centres that the ETA boiler complies with the
new limit values. To be fair, however, it should be noted
that high-quality fuels were used and the heating
system operated under optimal conditions. Things look
different in practice. Low-quality fuels are often used,
which represents a problem for the dust limit value.
Fuels used for testing
The following fuels were used as test fuel for emission
measurements and approval of the boiler:
• Conifer wood chips without bark according to EN
ISO 17225-4 with the designation "P31S M25 F05
A0.5"
• Pellets according to EN ISO 17225-2 with the
designation "D06 M10 A0.5"
The ash content of the fuel is an indicator for the
dust emission
According to the current state of science, dust
emissions from complete combustion are inorganic
components in the fuel, so-called aerosol formers.
Studies by renowned research institutes have clearly
demonstrated that the aerosol formers present in the
fuel (e.g., potassium, calcium, sulphur, chlorine,
sodium, zinc, silicon, phosphorous...) are released in
relatively fixed proportions. Accordingly, the level of
dust emissions is determined by the proportions of
these aerosol formers in the fuel.
The situation is made difficult by the fact that the
percentage of aerosol formers in the wood depends on
many factors (tree species, soil condition, season…).
Even different parts of the tree (trunk, branches, core/
sapwood) can demonstrate stark fluctuations.
In practice, the ash content of the fuel has proven to be
a good indicator of the percentage of aerosol formers.
In order to operate the system with the lowest possible
dust emissions, a properly maintained condition as
well as high-quality fuels with the lowest possible ash
content (barks, impurities, leaves, needles...) are indis-
pensable.
The Clean Air Act 1993 and Smoke Control Areas
Under the Clean Air Act local authorities may declare
the whole or part of the district of the authority to be a
smoke control area. It is an offence to emit smoke from
a chimney of a building, from a furnace or from any
fixed boiler if located in a designated smoke control
area. It is also an offence to acquire an "unauthorised
fuel" for use within a smoke control area unless it is
used in an "exempt" appliance ("exempted" from the
controls which generally apply in the smoke control
area).
In England appliances are exempted by publication on
a list by the Secretary of State in accordance with
changes made to sections 20 and 21 of the Clean Air
Act 1993 by section 15 of the Deregulation Act 2015.
Similarly in Scotland appliances are exempted by
publication on a list by Scottish Ministers under section
50 of the Regulatory Reform (Scotland) Act 2014.
In Wales and Northern Ireland these are authorised by
regulations made by Welsh Ministers and by the
Department of the Environment respectively.
The ETA HACK 20, 25, 35, 45, 50, 70, 90, 130 and
200 kW boiler has been recommended as suitable for
use in smoke control areas when burning wood chips
according to EN ISO 17225-4, P16S-P31S (G30-G50)
with a maximum water content of 35% and with an
optionally available flue gas recirculation, wood pellets
according to EN ISO 17225-2-A1 or EN plus class A1.
Further information on the requirements of the Clean
Air Act can be found here:
https://www.gov.uk/smoke-control-area-rules
Your local authority is responsible for implementing the
Clean Air Act 1993 including designation and
supervision of smoke control areas and you can
contact them for details of Clean Air Act requirements.
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