User Manual

31
AUTOMATIC CONTROL
1 HEATING CONTROL BT Reason for energy savings
1.3
Control of distribution network hot water temperature
(supply or return)
Similar function can be applied to the control of
direct electric heating networks
0
No automatic control The highest design temperature of all
consumers is continuously provided in
distribution, resulting in significant energy losses
under part load conditions.
1
Outside temperature-compensated control
Actions generally lower the mean flow
temperature
Distribution temperature is controlled depending
on the outside (corresponding to the probable
temperature demand of the consumers). This
reduces energy losses under part load
conditions.
2
Demand-based control
E.g. based on indoor temperature control
variable; actions generally lower the mean flow
temperature
Distribution temperature depending on the room
temperature (controlled variable). It considers
heat sources in the room as well (solar
irradiance, people, animals, technical
equipment). Keeps energy losses under part
load conditions at an optimum (low).
1.4 Control of distribution pumps in networks
The controlled pumps can be installed at different
levels in the network. Control is to reduce the
auxiliary energy demand of the pumps.
0
No automatic control No savings, since electrical power for the pump
is drawn continuously.
1
On / off control
switch on and off automatically, pumps run with
no control at maximum speed
Electrical power for the pump is drawn only as
required – e.g. during occupancy periods or in
protection mode (frost hazard).
2
Multi-stage control
Speed of pumps is controlled by a multi-step
control
Operating at a lower speed reduces power
consumption of multi-speed pumps.
3
Variable speed pump control
constant or variable Δp based on pump unit
(internal) estimations
8
a) With constant Dp: Pressure differential does
not increase at decreasing load when
maintaining a constant pressure differential
across the pump. The pump speed is
reduced under part load conditions, which
lowers power consumption.
b) With variable Dp: Pressure differential across
the pump drops as the load decreases. This
provides additional reductions in speed and
electrical power under part load conditions.
4
Variable speed pump control
variable Δp following an external demand signal,
e.g. hydraulic requirement, ΔT, energy
optimization
With variable Dp following an external demand
signal, the pump speed is reduced under part
load conditions as much as possible whilst
ensuring, that the consumer with the largest
demand is still satisfied at any given operational
situation, i.e. no underprovisioning of certain
consumers. This lowers power consumption
maximally.