York WR300 User Manual

262292-YTG-B-0107

54

Unitary Products Group

The outdoor fans shall be of the direct-driven propeller type, 
discharge air vertically, have aluminum blades riveted to 
corrosion resistant steel spider brackets and shall be 
dynamically balanced for smooth operation. The 4 outdoor fan 
motors shall be totally enclosed with permanently lubricated 
bearings, internally protected against overload conditions and 
staged independently. 

Compressors:

a. Shall be Scroll compressors internally protected with

internal high-pressure relief and over temperature
protection.

b. Shall have internal spring isolation and sound muffling to

minimize vibration and noise, and be externally isolated
on a dedicated, independent mounting. 

Coils:

a. Evaporator and condenser coils shall have aluminum

plate fins mechanically bonded to seamless internally
enhanced copper tubes with all joints brazed. Special
Phenolic coating shall be available as a factory option.

b. Evaporator and Condenser coils shall be of the direct

expansion, draw-thru, design. 

Refrigerant Circuit and Refrigerant Safety Components shall 
include:

a. Balance-port thermostatic expansion valve with

independent circuit feed system.

b. Filter drier/strainer to eliminate any moisture or foreign

matter.

c. Accessible service gage connections on both suction

and discharge lines to charge, evacuate, and measure
refrigerant pressure during any necessary servicing or
troubleshooting, without losing charge. 

d. The refrigeration system shall provide at least 10° F of

sub-cooling at design conditions.

e. All models shall have two independent circuits.

f. Hot gas bypass option shall be factory-installed on

compressor #1 discharge line to provide cooling in low-
load applications. HGBP shall be a standard feature on
VAV models and an optional feature on CV models.

a. Unit shall be complete with self-contained low-voltage

control circuit protected by a resetable circuit breaker on
the 24-volt transformer side.

b. Unit shall incorporate a lockout circuit which provides

reset capability at the space thermostat or base unit,
should any of the following standard safety devices trip
and shut off compressor.

c. Loss-of-charge/Low-pressure switch.

1. High-pressure switch.

2. Freeze-protection thermostat, evaporator coil. If any of 

the above safety devices trip, a LED (light-emitting 
diode) indicator shall flash a diagnostic code that 
indicates which safety switch has tripped.

d. Unit shall incorporate "AUTO RESET" compressor over

temperature, over current protection.

e. Unit shall operate with conventional thermostat designs

and have a low voltage terminal strip for easy hook-up.

f. Unit control board shall have on-board diagnostics and

fault code display.

g. Standard controls shall include anti-short cycle and low

voltage protection, and permit cooling operation down to
0 °F.

h. Control board shall monitor each refrigerant safety switch

independently.

i. Control board shall retain last 5 fault codes in non volatile

memory, which will not be lost in the event of a power
loss.

Shall be designed with induced draft combustion with post 
purge logic and energy saving direct spark ignition, redundant 
main gas valve. Ventor wheel shall be constructed of stainless 
steel for corrosion resistance. The heat exchanger shall be of 
the tubular type, constructed of T1-40 aluminized steel for 
corrosion resistance and allowing minimum mixed air entering 
temperature of 25° F. Burners shall be of the in-shot type, 
constructed of aluminum coated steel and contain air mixture 
adjustments. All gas piping shall enter the unit cabinet at a 
single location through either the side or curb, without any field 
modifications. An integrated control board shall provide timed 
control of evaporator fan functioning and burner ignition. 
Heating section shall be provided with the following minimum 
protection:

a. Primary and auxiliary high-temperature limit switches.

b. Induced draft motor speed sensor.

c. Flame roll out switch (automatic reset).

d. Flame proving controls. Unit shall have two independent

stages of capacity. 

Nickel chromium electric heating elements shall be provided as 
required by the application with 1 or 2 stage control, as 
required, from 13.5 KW to 72 KW capacities. The heating 
section shall have a primary limit control(s) and automatic reset 
to prevent the heating element system from operating at an 
excessive temperature. Units with Electric Heating shall be 
wired for a single point power supply with branch circuit fusing 
(where required).