Specifications

Page 39
C2-1 DIAGRAM WITH D5 DIAGRAM
Electromechanical Thermostat with Modulating Economizer and WarmUp
WARMUP KIT
An optional feature of the REMD24M economizer is a warmup kit which holds the economizer
outdoor air dampers closed during night heat operation and while the GCS24 is warming the build
ing the morning after. The warm-up kit temporarily disables the economizer (outdoor air dampers
are held closed) during morning warm-up to keep cool outside air from being mixed with return air.
Once the temperature setpoint is reached, the economizer is allowed to operate normally (outdoor
air dampers open to minimum position to allow required minimum air exchange).
NOTE-In order to understand how optional controls affect the operation of the GCS24, you must
first read and understand how all the GCS24 components work.
NOTE-
The warm-up kit requires the use of optional time clock CMC3-1.
Optional night thermostat S12 must be installed.
The warm-up kit can only be installed in GCS24 units with REMD16 economizer.
WARNING-CONNECT ONLY RELAY KITS DESIGNED FOR THIS CONTROL SYSTEM.
RELAY KITS DESIGNED FOR OTHER CONTROL SYSTEMS ARE NOT COMPATIBLE
AND CONTROL DAMAGE OR FAILURE WILL RESULT. FOR EXAMPLE, A W973 RELAY
KIT MUST NOT BE CONNECTED TO A ELECTROMECHANICAL THERMOSTAT CON
TROL SYSTEM.
WARNING-BE CAREFUL TO CONNECT RELAY KITS TO THE PROPER JACK AND PLUG
IN THE GCS24 BLOWER COMPARTMENT. REFER TO WIRING DIAGRAM. IMPROPER
CONNECTION WILL CAUSE CONTROL FAILURE.
The warmup kit installs in the control mounting area of the GCS24 filter access compartment. No
wiring is required. Jumper plug P3 is removed and discarded. Warmup kit harness plug P8 con
nects directly into jack J3 in the blower compartment. Warmup kit harness jack J8 connects to
economizer harness plug P4.
Operation Sequence:
NOTE-This operation sequence emphasizes warmup kit operation. Unit diagram has been
omitted.
1- When relay K41 is energized during normal operation, the economizer functions normally and is
lockedin until night setback. When relay K41 is de-energized, economizer is disabled.
2- Economizer outdoor air dampers drive full closed anytime blower B3 is not operating.
Night Setback:
3- Time clock CMC3-1 should be adjusted so that clock contacts remain closed during hours when
the building is not occupied. The contacts are set to open shortly (usually 1 hour) before the build
ing is to be occupied.
4- When clock contacts close, relay K11 in the economizer and K42 in the warmup kit are ener
gized.
5- Contacts K11-1 open to disconnect power to thermostat S1. K11-2 open to drive the dampers full
closed.
6- Contacts K42-1 open to disengage relay K41.
7- When relay K41 disengages, power is disconnected to the economizer:
a-Contacts K41-1 open to lockout economizer operation.
b-Contacts K41-2 close (not used).
c-Contacts K41-3 open to disconnect power to the economizer.
d-Contacts K41-4 open (not used).
8- During unoccupied periods, K11-1 opens and S1 is disabled. When S12 closes, power is returned
to S1 and the unit operates (heating demand) normally. When S12s setpoint is reached, S12
opens, S1 is disabled and unit operation stops.
9- Blower operates only on demand energized by GCS24 heat relay K25 when S12 is closed.
10- Thermostat S1 and economizer remain inoperable until time clock CMC3-1 contacts open.
First Heat Demand After Night Setback (Begin Warm-Up)
11- Shortly before the building is to be occupied, time clock CMC3-1 contacts open.
12- Relay K42 disengages and contacts K42-1 close.
13- Relay K11 disengages. Contacts K11-1 close to allow power to thermostat S1. Contacts K11-2
close to allow outdoor air dampers to open. Note that dampers remain closed until relays K3 and
K41 are energized.
14- Since contacts K40-1 are normally closed and contacts K42-1 have just switched closed, timer
DL7 is energized. Timer DL7 is normally open and closes 30 sec. after being energized.
15- If heat demand W1 reaches relay K40 before delay DL7 closes, contacts K40-1 open, delay DL7
loses power and resets and the economizer is locked-out for the first heat demand by relay K41
(contacts K41-3 remain open). If heat demand W1 reaches relay K40 after delay DL7 closes, relay
K41 energizes and the economizer locks-in for the day until night setback.
16- When first heat demand is satisfied, relay K40 disengages and relay K40 contacts K40-1 close.
Relay contacts K42-1 are already closed (clock contacts open). Time delay DL7 begins 30 sec.
count. If a second heat demand W1 does not reach relay K42 within 30 sec., time delay DL7
contacts close and relay K41 energizes.
17- When relay K41 energizes, the economizer is allowed to operate normally, controlled by relay K3:
a-Contacts K41-1 closes to lockin economizer operation until night setback.
b-Contacts K41-2 open (not used).
c-Contacts K41-3 close to allow power to the economizer.
d-Contacts K41-4 close (not used).
18- Once energized, relay K41 locks-in and the economizer operates until relay K42 is energized by
night setback (contacts K42-1 open to disengage relay K41).