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User Interface - Indicator LED
Power
• On when 115 V (ac) is applied.
• Off when power disconnected or transformer fuse is
blown.
Priority
• On when zone 1 has priority over zone 2.
• Flashing while in priority override.
RoomResponse
TM
• On when modulating condensing boiler is operating
below maximum setting.
Zone 1
• On when thermostat 1 calls for heat.
Zones 2
• On when thermostat 2 calls for heat.
• Off during priority operation.
• Off when corresponding thermostat stops calling for
heat.
Sequence of Operation
Zone Operation
When a thermostat calls for heat by closing the R and W
terminals:
• 115 V (ac) is applied to the corresponding circulator pump.
• The corresponding zone indicator LED is turned on.
Boiler Operation
When a thermostat calls for heat by closing the R and W
terminals:
• The boiler end switch XX is closed to fire the boiler.
This requires the control DIP switch to be set to
Master.
• The RoomResponse
TM
0-10 V (dc) or 4-20 mA signal is
sent to a modulating-condensing boiler.
DHW Operation
Many modulating-condensing boilers have multiple tem-
perature call inputs. Wire the DHW end switch to input
recommended in the boiler's manual.
When a zone 1 calls for heat by closing the R and W terminals:
• The DHW end switch is closed to fire the boiler at the
DHW temperature.
• The Mod Boiler output is changed to 10 V (dc) or 20 mA.
Priority Override
• The Priority LED light flashes when priority override is
in effect.
• Priority for zone 1 is in effect for 60 minutes after
which priority override starts by shutting off zone 1
and resumes heating on zone 2 and expansion zones.
• During priority override, the mod max dial setting
limits the RoomResponse
TM
signal to the boiler.
Master / Member DIP Switch
• Allows for unlimited expansion using additional
Switching Relays and/or Zone Valve Controls.
• The Master Switching Relay is wired and operates the
boiler.
• If using a single Switching Relay set to Master.
• When using multiple Switching Relays and/or Zone
Valve Controls, set one control to Master and set all
other controls to Member.
• The boiler end switch XX only closes when the DIP
switch is set to Master and does not close when set to
Member.
T-Stat 1 Priority DIP Switch
When T-Stat 1 is calling for heat by closing the R and W
terminals:
• 115 V (ac) is applied to the zone 1 circulator pump.
• Zone 1 indicator LED is turned on.
• Priority indicator LED is turned on.
• Zone 2 circulator pumps and LEDs are turned off.
• Expansion Member controls shut off their zones.
• After 60 minutes of continuous zone 1 call for DHW
heating the control goes into priority override. This
prevents building freeze up if the DHW tank aquastat
fails in the closed position.
Exercising DIP Switch
• ON: Each circulator pump is energized for 30
seconds every 72 hours.
• OFF: Circulator pump exercising disabled.
Post Purge DIP Switch
• ON: After the last thermostat stops calling for heat,
the last circulator pump remains on for 2 minutes to
purge heat from the boiler to the zone.
• OFF: Post purge disabled.
Mod Boiler DIP Switch
• Select either 0-10 V (dc) or 4-20 mA signal to the
modulating condensing boiler. Consult the boiler
manual to determine the signal type. The DIP switch
position does not matter if the modulating boiler
output is not used.
Fuses
• All fuses are T5A 250V slow blow, glass 5 x 20 mm.
• Fuses 1 and 2 correspond to the zone 1 and 2
circulator pump output. If a fuse is blown, first check
that the pump is not seized and the wiring is not
shorted. Then replace the fuse.
• Fuse 7 and 8 correspond to the 24 V (ac) transformer
power supply. If a fuse is blown, first check that the
thermostat wiring is not shorted. Then replace the
fuse.
Expansion Terminals
• Connect the five wires of the expansion bus from the
master to the member controls.
Terminal Description
A/tN4
Away signal connecting tekmar thermostats
B
RoomResponse
TM
signal from member controls
C
Power common
D
Demand signal. 0 Vdc = demand. 2 Vdc = no
demand
E
Priority signal. 0 Vdc = priority. 2 Vdc = no priority
