Selection Of Control Mode; Automatic Night-Time Duty - Grundfos MAGNA 2000 Series Installation And Operating Instructions Manual

7.2 Selection of control mode

System type Description
Grundfos recommends to let the pump remain in AUTO
Typical heating
This ensures optimum performance at the lowest possible energy
systems
consumption.
1. Two-pipe
heating
systems with
thermostatic
valves and:
Relatively great
head losses in
the distribution
pipes and air-
conditioning
systems
2. Primary circuit pumps in systems with great head losses in the primary
circuit.
3. Air-
conditioning
systems with
1. Two-pipe
heating
systems with
thermostatic
valves and:
Relatively small
head losses in
the distribution
pipes
2. Underfloor heating systems with thermostatic valves.
3. One-pipe heating systems with thermostatic valves or pipe balancing
valves.
4. Primary circuit pumps in systems with small head losses in the primary
circuit.
7.2.1 Setpoint setting
If AUTO is selected, the setpoint cannot be set.
ADAPT
The setpoint can be set by pressing
the pump is in control mode:
• proportional pressure,
• constant pressure or
• constant-curve duty.
Set the setpoint so that it matches the system.
A too high setting may result in noise in the system
whereas a too low setting may result in insufficient
heating or cooling in the system.
• with a dimensioned pump head higher than
3 metres,
• very long distribution pipes,
• strongly throttled pipe balancing valves,
• differential pressure regulators,
• great head losses in those parts of the system
through which the total quantity of water flows
(e.g. boiler, heat exchanger and distribution pipe
up to the first branching).
• heat exchangers (fan coils),
• cooling ceilings,
• cooling surfaces.
• with a dimensioned pump head lower than
2 metres,
• dimensioned for natural circulation,
• with small head losses in those parts of the system
through which the total quantity of water flows
(e.g. boiler, heat exchanger and distribution pipe
up to the first branching) or
• modified to a high differential temperature between
flow pipe and return pipe (e.g. district heating).

7.3 Automatic night-time duty

To be set on the control panel or with the R100, see
or when section 8. Setting the pump.
Once automatic night-time duty has been activated,
the pump automatically changes between normal
duty and night-time duty (duty at low performance).
Changeover between normal duty and night-time
duty is dependent on the flow-pipe temperature.
The pump automatically changes over to night-time
duty when the built-in sensor registers a flow-pipe
temperature drop of more than 10-15 °C within
approx. 2 hours. The temperature drop must be at
least 0.1 °C/min.
Changeover to normal duty takes place without a
time lag when the temperature has increased by
approx. 10 °C.
Note
mode.
ADAPT
Automatic night-time duty cannot be
used in air-conditioning systems.
Select this
control mode
AUTO
ADAPT
Proportional
pressure
Constant
pressure
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