The differential pressure by-pass valve can be fitted in any position,
respecting the flow direction indicated by the arrow on the valve body.
In systems with a traditional boiler it is normally fitted between the
system flow and return ends, which allows the control of the pressure
and the passage of a minimum flow through the heat generator.
In systems with a condensation boiler, it is preferable to fit the
by-pass directly between the upstream and downstream sections of
the pump, as this allows a higher
∆
T in the circuit, with lower return
temperatures and therefore better operation of the system.
In the event of high by-pass flow rate levels, it is recommended to fit
the valve between the flow and return ends of each column, rather
than fitting a number of valves in parallel at the central boiler.
mH2O
1
2
3
4
5
6
Installation
To regulate the valve, turn the knob to the required value on the
graduated scale: the values correspond to the differential pressure in
psi or meters w.g. to open the by-pass.
For a quick setup adjustment of the differential pressure by-pass
valve, use the following manual method. As an example, a hydronic
system with several zone valves: the system must be operating, the
zone valves must be fully open and the by-pass valve must be set to
the maximum value (a) (clockwise). Gradually open the differential
pressure by-pass valve using the control knob (counterclockwise).
Use a thermometer, or simply your hand, to check that the hot water
is flowing into the by-pass circuit (b). As soon as a rise in the
temperature is noted, turn control knob (clockwise) one half turn
closed so hot water stops flowing into the by-pass (c). Lock the knob
in this position (d) with the locking screw.
Adjustment
mH2O
1
2
3
4
5
6
mH2O
1
2
3
4
5
6
a)
b)
c
mH2O
1
2
3
4
5
6
mH2O
1
2
3
4
5
6
c)
d)
Hydraulic
characteristics
code 519502A, 519566A
519599A (3/4”)
∆
p
(psi)
1
2
0.5
0
1.5
G
(
m
3
/h
)(gpm)
∆
p
(psi) (m w.g.)
0
1
2
3
4
5
6
7
0
10
1
2
3
4
5
6
7
8
9
11
0
10
1
2
3
4
5
6
7
8
9
11
1
5
4
3
2
6
7
8
9
0
2
4
6
8
10
Setting positions
