Reznor OUH 100, Installation And Operating Manual

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1.11.1.2 Mechanical Ventilation to the Heated Space.
In the event that the heated space has a design air change of less than 0.5 air changes per hour and that installer
prefers to mechanically ventilate the heated space rather than provide ventilation openings then:-
The heated space needs to be mechanically ventilated so that the design air change is 0.5 air changes or greater.
It is a requirement that the mechanical ventilation shall be of the ‘input’ type with either natural or mechanical extraction.
Systems of mechanical extraction with a natural inlet shall not be used.
It is necessary to provide an automatic means to safely inhibit heater(s) operation should mechanical air supply fail for
any reason.
1.11.2 Heaters Installed within a Plant Room or Enclosure.
A plant room means a room housing the heater plant and probably other items of building service plant and would
generally have generous space for maintenance.
An enclosure is where the heater is installed within a compartment or confined area where space is limited. Where
heaters are installed within a plant room or enclosure then provision for both combustion air and air for general
ventilation will be required by means of high and low level ventilation openings (sections 1.11.2.1 refers to plant room
applications and sections 1.11.2.2 refers to enclosure applications).
Alternatively the plant room or enclosure may be mechanically ventilated (section 1.11.2.3 refers).
1.11.2.1 Natural Ventilation Openings to Plant Rooms
For plant room applications the minimum free area of ventilation
opening shall be:
At high level 2 cm2 for each kW of rated heat input.
At low level 4 cm2 for each kW of rated heat input.
The high level ventilation opening should be sited on an external wall
and positioned as high as is practical and always within the top 15%
of the wall height.
The low level natural ventilation opening should be situated on an
external wall and be within 1000 mm of floor level.
The table below provides specific data for each heater model as -
1.11.2.2 Natural Ventilation Openings to Enclosures
For enclosure applications the minimum free area of ventilation
opening shall be:
At high level 5 cm2 for each kW of rated heat input.
At low level 10 cm2 for each kW of rated heat input.
The high level ventilation opening should be sited on an external wall
and positioned as high as is practical and always within the top 15%
of the wall height
The low level natural ventilation opening should be situated on an
external wall and be within 1000 mm of floor level.
The table in the next column provides specific data for each heater model as:-
1.11.2.3 Mechanical Ventilation to a Plant Room or Enclosure.
Minimum Free Area of ventilation opening
Model High Level cm² Low Level cm²
40 88 176
60 128 258
70 166 332
90 192 384
100 230 460
Minimum Free Area of ventilation opening
Model High Level cm² Low Level cm²
40 220 440
60 320 640
70 415 830
90 480 960
100 575 1150