Page No 16 of 52 Reznor, RHC21 8000 Installation EN May 2021 D301319 Issue 0
4.7 Combustion air supply & flue system
RHC21 8000 heaters may be installed as a
Type C room sealed heater requiring both a
combustion air inlet pipe and a flue pipe (Type
C13, C33 or C53 only) or as a Type B forced
draught heater where the combustion air is
taken from the room space the air handling
unit / heater module is installed in and
which requires only a flue pipe exhausting to
outdoors (Type B23 or B53 only). All products
of combustion must be flued to outdoor
atmosphere.
The heaters are designed to operate safely and
efficiently with either a horizontal or vertical flue
system when installed according to the specific
requirements and instructions.
If the module is replacing an existing heater,
ensure that the flue is of the correct size and
that the existing flue is in good condition.
A correctly sized flue system is required for safe
operation of the heater.
For testing, the flue pipe should include a
sealable test point. Ideally the test point should
be at least 450mm away from the air heater flue
connection socket. However if a concentric flue
is attached directly to the connection sockets
then the combustion should be tested through
the flue outlet collar via a drilled test point
which must be securely plugged on completion.
Follow the flue pipe manufacturer’s installation
instructions for making joints, including
connections to the air heater, for passing
through a building element and for support
requirements.
Gasket sealed single wall seamless aluminium
or stainless steel flue pipes are required. All
joints must be sealed to prevent the products of
combustion from leaking into the building.
The products of combustion from
the heater must be flued to the
outside of the building.
A properly sized flue system is
required for safe operation of the
heater.
The flue MUST be installed in
accordance with national and local
regulations.
An improperly sized flue system
can cause unsafe conditions and/or
create condensation.
Failure to provide proper flueing
arrangements could result in death,
serious injury and/or damage to
property.
It is important to ensure that there
is an adequate clean air supply at
all times for both combustion and
heating requirements. Modern
buildings involve greater use
of insulation, improved vapour
barriers and weather proofing.
These practices mean that buildings
are sealed much tighter than in the
past.
Proper combustion air supply for a
power vented Type B installation
requires ventilation of the heated
space. Natural infiltration of air
may not be adequate. Use of
exhaust fans aggravates this
situation.
It is important to ensure that there
is adequate combustion air supply
at all times. Reliance on doors and
windows is not permitted.
Ensure that an adequate clean
air supply for combustion and
ventilation is provided within the
building in accordance with the
relevant rules and regulations in
force.
