User guide

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Other Boiler Controls
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The DU146 M 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.
Specially designed for disctrict heating systems, but can also be used for pump-driven warm water
heating systems.
The E121 air vent is a reliable automatic venting device and is suitable for venting air or gas from
heating systems or heat process installations.
For hot water heating systems, radiators, wall- and ceiling-mounted air heaters, air collection vessels,
pipework circuits, boilers and air separators. Not suitable for mineral oil or liquids with mineral-oil
based additives.
Service parts
DU146 M Automatic bypass and differential pressure valve for district heating sys-
tems
Materials Brass housing, spring bonnet and valve disc, plastic adjuster
knob, stainless steel spring, EPDM seals
Body pattern angle
Medium type water or water-glycol mixture according to VDI 2035
Max. media temperature 130
o
C
Max. operating pressure 16 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
Flow rate V = 3 cubic metres/h DU146M-3/4A
Flow rate V = 10 cubic metres/h DU146M-11/4A
E121 Automatic air vent
Materials Brass housing and lid, high-grade plastic float, heat-resistant
elastomer seal components
Medium type water or water-glycol mixture according to VDI 2035
Max. media temperature 110
o
C
Static pressure PN10
Port connection type external threads
Additional description With fitted Z 121 A shut-off valve cleaning or replacement of the
seal and inner components can be carried out without draining the
system.
Product description Type
Standard version, connection size R 3/8 E121-3/8A
Standard version, connection size R 1/2 E121-1/2A
Shut-off valve, packing unit 12 pcs, for connection size R3/8"
Z121-3/8A
Shut-off valve, packing unit 12 pcs, for connection size R1/2"
Z121-1/2A
Air vent cap with float, packing unit 54 pcs, threaded connection 44x19, min.
installation depth for float 46mm
X121-AA