User Guide

Installation and operating instructions Wilo-Stratos/-D/-Z 31
English
8.3 Selecting the control system
Unit type System conditions Recommended
control system
Heating-/ventilation- and
air conditioning systems
with a system friction loss
(heating radiator +
thermostatic valve) ≤ 25%
of the total resistance
1. Two-pipe systems with thermostatic/
zone valves
• Pumping head > 13.1 ft (high head
systems)
• Very long distribution lines
• Heavily throttled branch shut-off
valves
• Branch differential pressure
regulator
• High pressure losses in those
system parts through which the
total volume flows (boilers/
refrigerating machines, poss. heat
exchangers, distribution line)
2. Primary circuits with high pressure
losses
Δp-v
Drinking water circulation
systems with resistance in
the generator circuit
≥ 50% of the resistance in
the ascending section
3. Drinking water circulation systems
with thermostatically controlled line
shut-off valves
Heating-/ventilation- and
air conditioning systems
with a system friction loss
in the generator/distributor
circuit ≤ 25% of the
resistance in the transfer
part (heating radiator +
thermostatic valve)
1. Two-pipe systems with thermostatic/
zone valves and high consumer
authority
• Pumping head ≤ 6.6 ft (low head
systems)
• Converted gravity systems
• Retrofitting to large temperature
spread (i.e. long-distance energy)
• Low pressure losses in the system
parts through which the total
volume flows (boilers/refrigerating
machines, poss. heat exchangers,
distribution line)
2. Primary circuits with low pressure
losses
3. Underfloor heating systems with
thermostatic or zone valves
4. Single-pipe systems with
thermostatic or branch shut-off
valves
Δp-c