Construction And Function; Differential Pressure Measurement - oventrop Multiblock TQ-RTL Einbau- Und Betriebsanleitung

4.2 Dimensions/Connection sizes
Radiator
Thermostatic
valve with
isolation
"Q-Tech"
Illustr. 3 Dimensions of fitting
Illustr. 4 Dimensions of mounting aid

5 Construction and function

5.1 Summary and functional description
The fitting is a combination consisting of a presettable
thermostatic valve, an isolating fitting and a return
temperature limiter (RTL) for use in two pipe heating
systems.
The thermostatic valve also maintains the differential
pressure at a constant value via the regulating cross-
section of the valve. Even where high differential
pressure variations occur, for instance if sections of
the system are activated or inactivated, the flow rate
is kept at a constant level within the regulation
tolerances.
This way, the valve authority of the thermostatic valve
amounts to 100 % (a = 1). Even during part load
conditions with steady control (for instance in
combination with thermostats for room temperature
control), the valve authority of the thermostatic valve
amounts to 100 % (a = 1) within the effective valve lift.
The maximum flow rate can be set with the help of the
presetting key (pos. 4, illustr. 5) (see paragraph 7.3).
For additional room temperature control, thermostats
or actuators with OV connection thread M 30 x 1.5
can be screwed onto the thermostatic valve. See
Oventrop catalogue "Products".
Surface temperature balance is carried out independent
of the thermostatic valve by limiting the return
temperature via the integrated return temperature
limiter.
During design it must be observed that the pressure
loss of the pipework and the return temperature limiter
does not exceed a sum of 30 kPa (300 mbar).
The fitting is used at radiators with female thread G ½
(F) with a distance of 50 mm between the pipe centres.
5.2 Construction
Illustr. 5 Construction thermostatic valve

5.3 Differential pressure measurement

The available differential pressure can be measured
with the help of the OV measuring systems ("OV-DMC
2" or "OV-DMPC") together with the "Demo-Bloc" (item
no. 1188051 with 1188094) and the differential pressure
measuring stem (item no. 1188093). This will confirm
if the differential pressure is high enough for an
automatic flow control of the valve. The pump setting
may also be optimised by measuring the differential
pressure.
For this purpose, the pump head is reduced until just
the minimum required differential pressure is available
at the hydraulically most underprivileged valves.
With a flow meter connected, the differential pressure
at the thermostatic valve body is measured. To do so,
the valve insert (pos. 2, illustr. 5) is unscrewed with the
help of the "Demo-Bloc" and the differential pressure
is measured using the differential pressure measuring
stem. As soon as the measured differential pressure
has reached or exceeded the differential pressure Δp
min. (see 4.1), the differential pressure is high enough
for an automatic flow control of the valve.
Screw the valve insert into the valve body again and
check all installation points for leaks.
NOTICE
The valve insert is tightened with a torque of 15 Nm.
Use a 19 mm spanner for mounting or dismounting
the valve insert.
1 Body
2 Valve insert
2b Handwheel
2b Filter mesh
3 Protection cap
4 Presetting key
∆p Differential pressure
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