User guide

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Other Boiler Controls
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Accessories for DU 145-3/4 A
Accessories for DU 145-3/4 E
The DU146 automatic bypass and differential pressure valve is used to maintain a constant differential
pressure in a heating system. It reduces flow noise in a system, particularly as thermostatic radiator
valves are closed. The boiler return temperature is raised and this reduces corrosion caused by flue
gas condensation. In addition, when radiator valves are closed it also maintains flow over the
temperature sensor on the boiler to ensure proper operation of external temperature compensation
controls. On gas-fired water heaters it guarantees a minimum flow circulation when thermostats or
radiator valves are closed.
For pump-driven warm water heating systems, e.g.:
• On heating systems with three-way or four-way mixing valves, or
• on gas-fired hot water circulation heating systems.
Accessories
Product description Port connection type Type
Supplied with externally threaded connections external threads DU145-3/4A
– internal threads DU145-3/4E
2 soldering connections for 22 mm pipe
VST06-3/4B
Compression ring with backnut, 3/4 x 18 mm
ZS109M-3/4G
Compression ring with backnut, 3/4 x 22 mm
ZS109M-3/4H
2 compression rings with backnuts and support inserts, 3/4 x 18 mm
ZS109M-3/4GS
2 compression rings with backnuts and support inserts, 3/4 x 18 mm
ZS109M-3/4GS
DU146 Automatic bypass and differential pressure valve with differential pressure
indicator
Materials Brass housing, fittings and valve disc, plastic spring bonnet
assembly, composite glass display tube, stainless steel spring,
EPDM seals
Body pattern angle
Medium type water or water-glycol mixture according to VDI 2035
Max. media temperature 110
o
C
Max. operating pressure 3 bar
Differential pressure
setpoint range
0,05 ... 0,5 bar
Port connection type internal threads
Additional description Special versions available on request.
Product description Type
For installations up to approx. 70 kW (60.000 kcal/h) DU146-3/4A
For installations up to approx. 232 kW (200.000 kcal/h) DU146-11/4A
Indicator tube assembly, consisting of indicator tube, inner tube, spring, indicator
piston and 5 O-rings
DU146AH-A