46TD 204
Head Pressure Control Valve
[Headmaster]/Fan Cycle Switch
(Remote Units Only)
discharge
receiver
condenser
above 70°F
normal
dis-
charge
receiver
condenser
below 70°F by-pass
The Cornelius “I” series remote systems use an Alco Head Pressure
Control, normally referred to as a headmaster. This control is
mounted in the remote condenser with a fan cycling control switch.
Using both these controls gives the system positive operation under
a wide range of condensing temperatures.
The fan cycling switch starts the fan at 270 PSI (18.62 Bars) and stop
it at 205 PSI (14.13 Bars) allowing a positive efficient operation at
the high temperature operating ranges.
The headmaster controls the operation when the condensing tem-
perature drops below 21.1°C. The “I” series refrigerant charge is
HP - 62 [R - 404A] and the headmaster dome charge setting is 200
PSI (13.79 Bars) of nitrogen pressure making it stable under the low
temperature operating range down to - 29°C. (Continued on page
46).
The normal flow pattern through the headmaster is from the con-
denser port to the receiver port. When this flow pattern is unable to
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