11
Sequence of Operation / Settings
• A single “master” thermostat is wired to the
ZSR101 control. The master thermostat is set
to a slightly higher set point than the desired
room temperatures on the thermostatic
radiator valves.
•
When the temperature drops below the
thermostat’s set point, a heat demand is
initiated by closing the R & W terminals.
•
Relay #1 and relay #2 both fire.
•
If the factory installed jumper has not been
removed, the NO terminal of relay #1 will
deliver 120 VAC line to the variable speed
circulator.
•
Relay #2 closes the TT contacts on the boiler
signaling a demand.
•
The Zone LED illuminates.
•
Using an outside air sensor and system
temperature sensor located in the buffer tank,
the boiler determines if the water in the boiler
meets the target temperature based off the
outside air reset curve.
•
As long as the master thermostat is calling,
the boiler will maintain the buffer tank to the
target temperature.
•
The thermostatic radiator valves modulate the
flow through the panel radiators because the
variable speed circulator is enabled.
•
When the master thermostat reaches set
point, the master thermostat will open the
contact between R & W.
•
The relay contacts return to their normal
position turning off power to the variable
speed circulator and opening the RW (TT)
contacts. Both the boiler and pump are
no longer enabled.
•
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
