tekmar 704 Mixing Station - Manual (Page 7)

7 of 16 © 2005 D 704 - 04/05
Outdoor Design
The Outdoor Design temperature must be set to OFF.
Mixing Target
The Mixing Target temperature is set to the desired operating temperature of the system.
Delta T Max
The Delta T Max temperature is set to the maximum temperature difference that is desired between the mixing return temperature
and the mixing supply temperature. In order to adjust this setting, a mixing return sensor must be connected to the control.
Setpoint and Delta T Settings
60
(16)
70
(21)
80
(27)
90
(32)
100
(38)
110
(43)
120
(49)
130
(54)
140
(60)
150
(66)
°F
(°C)
Supply T
em
per
ature
Boiler Operation
The RMC operates the boiler in two basic modes of operation. The RMC can either “Control” the boiler or “Enable” the boiler. The mode
of operation is determined by the Boiler Sensor location. The boiler sensor location is determined using the DIP switch on the back of
the circuit board. If the DIP switch is set to ON, the boiler sensor is to be located on the boiler supply. If the DIP switch is set to OFF, the
boiler sensor is to be located on the boiler return.
• If the DIP switch is set to On, the RMC will “Control“ the boiler.
• If the DIP switch is set to Off, the RMC will “Enable” the boiler.
• If the Boiler Sensor has not been installed, the RMC will “Enable” the boiler.
BOILER CONTROL
When the RMC controls the boiler, the RMC opens and closes the boiler contact in order to control the temperature of the boiler supply
water temperature. When the RMC is controlling the boiler temperature, the RMC will determine the boiler supply water temperature
that is required to satisfy the demands of the system. The RMC will also determine a differential that is suffi cient to minimize short
cycling of the boiler. The RMC will then cycle the boiler using these parameters.
Differential
An on / off boiler must be operated with a differential in order to prevent short cycling. When the supply water temperature drops
1/2 of the differential below the required boiler supply temperature, the boiler is turned on. The boiler is then kept on until the supply
Com Heat
Dem
Boil Out Unpowered
Demand
Switch
Unpowered Demand
The RMC recognizes an Unpowered Demand signal when a switch is closed between
the Com and Heat Dem terminals.
SYSTEM PUMP OPERATION
The RMC has an internal system pump contact. This contact turns on when the RMC has
a mixing demand. The system pump as well as an external boiler pump may be controlled
by this relay. By providing proper fl ow in the boiler loop, the boiler temperature can be ac-
curately controlled based on the mixing load.
60
(16)
70
(21)
80
(27)
30
(-1)
40
(4)
50
(10)
90
(32)
100
(38)
110
(43)
120
(49)
°F
(°C)
Supply T
em
per
ature