Reznor, RHC21 4000 Installation EN May 2021 D301334 Issue 0 Page No 19 of 56
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. If the flue
passes through a combustible element of the
building it must be enclosed by a sleeve of non-
combustible material and separated from the
sleeve by a minimum of 25 mm air break. The
temperature of any combustible material near
to the flue must not exceed 65°C when the
heater is in operation. The flue must be at least
150 mm away from any combustible material.
Single wall flue pipe exposed to cold air or run
through unheated areas should be insulated.
Where condensation is unavoidable, provision
must be made for the condensation to flow
freely to a point to which it can be released,
i.e. a drain or gully. The condensation drain
from the flue must be constructed from non-
corrodible material not less than 20 mm
diameter. Copper or copper based alloys must
not be used for condensation drains.
Vertical flue runs greater than 3m long will
require a condensate drain fitting between the
flue outlet of the heater and the vertical flue
pipe. Alternatively, insulated flue pipe should be
considered.
Horizontal flue runs should be installed with a
slight gradient of approximately 5° towards the
terminal.
Due consideration should be given to the
possibility of condensation from the flue
freezing on any footpaths that pass below the
terminal.
4.10 Gas supply
Note : gas service connection Rc 1/2 for model
RHC21 4024-05, Rc 3/4 for models RHC21 4036-
08 to 4100-12 inclusive and Rc 11/4 for models
RHC21 4125M15 and 4150M18.
RHC21 4000 air heaters are designed to operate
on natural gas (G20 / G25 / G25.3). Refer to the
specifications in section 2 of this document and
to the data plate for details of supply pressures.
A competent and/or qualified engineer is
required to either install a new gas meter to the
service pipe or to check that the existing meter
is adequate to deal with the rate of gas supply
required. Installation pipes should be fitted in
accordance with national standards so that the
supply pressure, as stated in the technical data
section will be achieved.
It is the responsibility of the competent engineer
to ensure that other relevant standards and
codes of practice are complied with in the
country of installation. Pipes of smaller size
than the heater inlet gas connection must not
be used. The complete installation must be
tested for soundness as described in the country
of installation. Support gas piping with pipe
hangers, metal strapping, or other suitable
material.
Do not rely on the heater to
support the gas pipework
installation.
Before installation, check that
the local distribution conditions,
nature of gas and pressure, and
adjustment of the appliance are
compatible.
This appliance is designed for a
maximum gas supply pressure of
50mbar. When pressure testing the
supply piping with test pressures
above 50mbar, disconnect the
heater and manual valve from the
gas supply line that is to be tested.
Cap or plug the supply line.
To facilitate servicing, the air heater must be
fitted with an approved gas service tap and
union fitting or union tap adjacent to the
appliance.
The inlet gas supply line must be installed so as
to permit the access door to be opened and to
allow removal of slide out burner assembly.
Check that the gas category is in accordance
with the data described on the air heater.
An adequate gas supply sized to provide the
dynamic pressure for the volume required for
the air heater(s) is essential to maintain the
nominal heat input.
