Reznor YDSA Unit Installation Manual - Manual (Page 37)

Form I-Y, P/N 273646R6, Page 37
9.1.3 Energy
Recovery Wheel,
Option EW__
The energy recovery wheel rotates through both the inlet and exhaust airstreams. The
function of the wheel is to transfer both sensible (temperature) and latent (moisture)
energy from one airstream to the air in the other airstream. This allows the energy
recovery module to both cool and dehumidify outdoor makeup air during the cooling
season and heat and humidify outdoor makeup air in the heating season before that
air enters the unit.
The wheel is rotated by a motor and non-adjustable belt drive. The speed of the rota-
tion is factory set to provide optimum energy transfer. Energy recovery wheel operation
is controlled by the system controller.
Outside Air or Outside and Return Air Dampers with Energy Recovery Wheel -
There are two airflow configurations available on a unit with an energy recovery
wheel. Options AR2L and AR2M (See FIGURE 21, page 35.) with motorized dampers
are identified on the unit wiring diagram. The outside air damper is always opened
prior to operation of the unit blower and the energy recovery wheel. The return air
damper in Option AR2M is interlocked with the outside air damper.
Optional Preheat Frost Control, Option PH2A (10kw), PH3A (20kw), or PH4A
(30kw) - If equipped with preheat frost control, electric elements heat the outside air
before it enters the wheel. The energy recovery preheat output NO16 will operate
whenever the supply air temperature to the wheel is less than 33°F/1°C (with a two
degree differential) and the outdoor air temperature is below 32°F/1°C (with a two
degree differential). Otherwise the electric heat is OFF.
WARNING
The operating valve is the prime safety shutoff. All gas supply
lines must be free of dirt or scale before connecting the unit to
ensure positive closure.
Furnaces for natural gas are orificed for operating with gas having a heating value of
1000 (±50) BTU per cubic ft. If the gas at the installation does not meet this specifica-
tion, consult the factory for proper orifice size.
Pipe joint compounds (pipe dope) shall be resistant to the action of liquefied petroleum
gas or any other chemical constituents of the gas being supplied.
9.2 Gas Heat
Section
9.2.1 Gas Supply Piping and Connections
All piping must be in accordance with requirements outlined in the National Fuel Gas
Code ANSI/Z223.1a (latest edition) or CSA-B149.1 and B149.2 (latest editions). Gas
supply piping installation should conform with good practice and with local codes.
WARNING: PRESSURE TESTING SUPPLY PIPING
This appliance is equipped for a maximum gas supply pressure
of 1/2 psi, 3.5 kPa, or 14 inches water column. NOTE: Supply
pressures higher than 1/2 psi REQUIRE installation of an additional
service regulator external to the unit.
Test pressure ABOVE 1/2 psi (3.5 kPa): Disconnect the heater and
the manual valve from the gas supply line which is to be tested.
Cap or plug the supply line.
Test pressure EQUAL TO or BELOW 1/2 psi (3.5 kPa): Before
testing, close the manual valve at the heater.