tekmar 263 Boiler Control User Manual

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Section F1: Setpoint

Section F1

Setpoint

Operation

Section F: Setpoint Operation

For correct operation, close attention must be paid to the mechanical layout of the system. When the control turns off the primary
pump (Prim P1), flow to the heating system must stop. If flow is not stopped, the temperature in the heating system can exceed the
maximum desired temperature and can result in damage to the heating system.

DHW MODE 4 OPERATION

In DHW MODE 4, the space heating zones must be prevented from coming on during DHW demands using external wiring. This
can be done using an external relay to remove power from zone pumps or zone valves while a DHW Demand is present. This
external relay is interlocked with the DHW Pmp / Vlv contact.

During a DHW Demand, the control closes the primary pump (Prim P1) contact and the DHW Pmp / Vlv contact. Once the DHW
Demand is removed, or during a DHW priority override, the DHW Pmp / Vlv contact is opened, and the external wiring should allow
the space heating zones to operate.

There is no mixing purge available in DHW MODE 4. After DHW priority, the boiler supply water temperature may exceed the design
water temperature of the space heating system and can result in damage to the heating system.

SETPOINT

The control can operate to satisfy the requirements of a setpoint load in addition to a
space heating load and a DHW load. A setpoint load overrides the current outdoor reset
temperature and WWSD setting in order to provide heat to the setpoint load.

SETPOINT DEMAND

A Setpoint Demand is required in order for the control to provide heat to the setpoint load.
The control registers a setpoint demand when a voltage between 24 and 230 V (ac) is
applied across the Setp Dem and Com Dem terminals (5 and 4). Once voltage is applied,
the Setpoint Demand pointer turns on in the LCD. The control operates the boiler(s) to
maintain at least the Setpoint setting.

BOILER TARGET DURING SETPOINT

The boiler target temperature during a setpoint demand is increased to at least the Setpoint setting. This temperature is maintained
as long as the control has a setpoint demand.

SETPOINT MODES

Mode 1 – Setpoint in Parallel

Whenever a setpoint demand is present, the boiler(s) is operated to maintain the setpoint target.

It is assumed that the Setpoint pump will provide adequate flow through the heat exchanger and the boiler.

Mode 2 – Setpoint in Parallel with Priority

Whenever a setpoint demand is present, the boiler(s) is operated to maintain setpoint
and the primary pump (Prim P1) is turned off.

It is assumed that the Setpoint pump will provide adequate flow through the heat
exchanger and the boiler.

Mode 3 – Primary Pump during Setpoint

Whenever a setpoint demand is present, the primary pump (Prim P1) is turned on and the boiler(s) is operated to maintain
setpoint target.

Primary

Pump

Setpoint
Pump

Com

Dem

Setp

Dem

24 to 230 V (ac)