York MILLENNIUM Y22 Installation Manual page 75

102777-YIM-E-0206
mum ON time for each cooling stage and a 5 minute min-
imum OFF time for each cooling stage.
5. A call for Compressor 1 powers the high pressure safety
switch (HPS1), the low pressure switch (LPS1), the coil
of contactor 6M (condenser fan 1), and the coil of con-
tactor 7M (contactor, condenser fan 2) through con-
denser fan cycling switch PS5 (PS5 disables condenser
fan 2 operation based upon the discharge pressure of
the Compressor 1). If the system pressures are within
HPS1 (high refrigerant pressure) and LPS1 (low refriger-
ant pressure) switch settings and the solid state com-
pressor motor protector (Compressor Module No. 1) is
not tripped, contactor 1M is engaged to start scroll Com-
pressor 1.
6. A call for Compressor 2 powers contactor 2M (contactor,
compressor 2) if HPS2, LPS2 (high and low refrigerant
pressure) and Compressor Module 2 (compressor motor
protector) contacts are closed.
7. 30 and 40 ton only: A call for Compressor 3 powers the
coils of contactors 8M (contactor, condenser fan 3) and
9M (contactor, condenser fan 4 - 40 ton only). If HPS3,
LPS3 (high and low refrigerant pressure) and Compres-
sor Module 3 contacts are closed, power is applied to the
coil of Contactor 3M, which starts compressor 3.
8. 40 Ton Only: A call for Compressor 4 powers the coils of
contactor 4M if HPS4, LPS4 (high and low refrigerant
pressure) and Compressor Module 4 contacts are
closed.
9. When the internal time clock matches the setting in the
holiday and daily schedules, the unit enters Unoccupied
mode. The control disables the supply fan, the optional
power exhaust, cooling, heating, and the economizer.
The optional outside air dampers are closed with the
optional inlet guide vanes.
10. When the space temperature falls below the heating set-
point, the control powers contactor 5M from terminal
FAN to engage the supply fan motor. If the supply fan
operates correctly (proper rotation) the pressure differ-
ence between the heating section and the supply fan
section increases and APS closes to enable heating
operation. If heat safeties are satisfied, the VAV speed
signal (VFD or Inlet Guide Vanes) goes to maximum flow
[the customer-installed connection will drive the VAV
boxes to full open]. The control engages unit heat
(optional) at full capacity. Until heat is energized, duct
pressure control is activated. The optional power
exhaust system is activated.
In heat mode, cooling is disabled and the optional econ-
omizer outside air dampers are closed. This operation is
maintained until the space temperature rises above the
heating setpoint or Occupied mode is engaged.
11. Gas Heat Option, Stage 1: A call for heat engages Igni-
tion Control 1 (IC1-terminal TH) from Simplicity terminal
H1. Once APS (supply air proving switch) closes to
Unitary Products Group
acknowledge supply airflow and the LIM1-3 safeties are
satisfied, IC1 is powered. IC1 closes contacts between
terminals L1 and IND to engage Draft Motor 1. The IC1
monitors PSW (draft fan air proving switch) and LS1
(heat limit switch, which opens only with excessive heat
exchanger temperature). When the safeties are satisfied,
IC1 will attempt ignition. IC1 provides direct spark igni-
tion with flame verification and controls the GV1 gas
valve through manual reset switch RS1 (rollout switch). If
RS1 has tripped, GV1 is locked out and IC1 will electron-
ically lockout after 3 failed ignition attempts. The Simplic-
ity control also monitors the voltage going to the gas
valve at terminals GV1-3.
When the W1 call is canceled, power is removed from
IC1 terminal TH, which directs IC1 to close GV1. As long
as APS continues to prove supply fan airflow, IC1
remains powered and keeps the L1 to IND contacts
closed for 45 seconds to maintain the operation of Draft
Motor 1 for a post-purge of the heat exchanger.
12. Gas Heat Option, Stages 2 and 3: These follow the
same rules as Stage 1. Separate terminals and safety
monitor circuits are wired to each installed heat stage.
For gas heat, there is a separate overtemperature limit
switch for each heat module.
13. Electric Heat Option: A call for heat stages electric heat
on. Electric heat is available as 40kW [one stage], 80kW
[two stages], or 108kW [three stages]. There is one over-
heat limit for electric heat, regardless of the number of
stages - contrasted with gas heat, which has individual
over-heat limits on each module.
On units with the Electric Heat Option, a call for heat
(W1) will initiate the main blower. The blower will pro-
duce static in the supply and the Air Proving Switch
(APS) contacts will close. The control recognizes closure
of the APS and energizes the H1 terminal to complete
the circuit to the first stage of electric heat.
In Occupied mode, if additional heat is required, the W2
signal will energize the second stage of electric heat
through terminal H2; W3 / H3 function similarly. When
the W2 call for heat has been satisfied, W2 will be de-
energized and will in turn de-energize H2 second stage
heat. As the call heat (W1) has been satisfied, W1 will be
de-energized. If the unit is in Unoccupied mode, the fan
will shut off and the APS will open. For units in space
sensor control, the Simplicity will stage on heat as
required to maintain space sensor temp, or SAT temp if
the space sensor signal is lost.
All electric heat modules have an auto-reset primary limit
and non-restartable back-up limits. Dirty filters, broken
belts, fan motor burn-out or running this unit below 6,000
CFM will cause the limit to trip on the auto-reset primary
limit. In addition to the primary limit, back-up limits may
trip under these conditions. The back-up limits are one-
trip devices and will have to be replaced should they trip.
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