9
Sequence of Operation / Settings
•
There is a demand by one of the t-stats which
sends power to the corresponding zone valve.
•
When the zone valve opens, its end switch
contacts close and signal a demand to the RW
(TT) contacts on the single zone relay control.
•
Relay #1 and relay #2 fire
•
If the factory installed jumper has not been
removed, the NO terminal of relay #1 will
deliver the hot leg of 120 VAC thus firing the
pump.
•
Relay #2 closes the TT contacts on the boiler
signally a demand.
•
The Zone LED illuminates.
•
When the last of the T-stats is satisfied, the
corresponding zone valves closes which
opens the end switch contacts.
•
The relay contacts return to their normal
position turning off power to the system pump
and opening the RW (TT) contacts.
•
The Zone LED turns off.
WARNING:
NEVER CONNECT R & C DIRECTLY,
this will be a direct short on the 24 VAC supply
Description of terminals
= Ground
N
= Neutral (Common leg of 120 VAC)
L
= Line (live leg of 120 VAC)
C
= Common terminal
NO
= Normally Open terminal
NC
= Normally Closed terminal
Note: There is a factory installed jumper between the 120
VAC line (L) and the common terminal of relay #1 (C).
Thermostat terminals
R = 24 VAC
W = Heat call
C = Common of 24 VAC
