Lennox CHA16 User Manual

Page 61
C2-1 DIAGRAM WITH D5 DIAGRAM
Electromechanical Thermostat with Economizer and WarmUp
C-WARMUP KIT
An optional feature of the REMD16M economizer is a warmup kit which holds the economiz
er outdoor air dampers closed during night heat operation and while the CHA16 is warming
the building 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 CHA16, you
must first read and understand how all the CHA16 components work.
NOTE-
1 - The warm-up kit requires the use of optional time clock CMC3-1.
2 - Optional night thermostat S12 must be installed.
3 - The warm-up kit can only be installed in CHA16 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 THERMO
STAT CONTROL SYSTEM.
WARNING-BE CAREFUL TO CONNECT RELAY KITS TO THE PROPER JACK AND
PLUG IN THE CHA16 BLOWER COMPARTMENT. REFER TO WIRING DIAGRAM. IM
PROPER CONNECTION WILL CAUSE CONTROL FAILURE.
The warmup kit installs in the control mounting area of the CHA16 filter access compart
ment. No wiring is required. Jumper plug P3 is removed and discarded. Warmup kit harness
plug P8 connects 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 nor
mally and is lockedin until night setback. When relay K41 is de-energized, economiz
er 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 building is to be occupied.
4 - When clock contacts close, relay K11 in the economizer and K42 in the warmup kit are
energized.
5 - Contacts K11-1 open to disconnect power to thermostat S1. K11-2 open to drive the damp
ers 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 ECH16 heat relay K9 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 ener
gized.
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 de
mand 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 be
gins 30 sec. count. If a second heat demand W1 does not reach relay K40 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 ener
gized by night setback (contacts K42-1 open to disengage relay K41).

Lennox CHA16 Specifications

General

Brand	Lennox
Model	CHA16
Category	Air Conditioner
Language	English