Use And Care Manual
Operating principle
The by-bass valve contains a
check valve connected to a contact
spring. When the fixed setting
pressure is reached, the valve plug
gradually opens, recirculating the
flow in proportion to the closing of
the thermo-electric valves and
maintaining a constant differential
pressure in the manifold circuit.
Construction details
The differential by-pass assemby
features a fixed setting that cannot
be changed because it does not
contain accessible adjustment
parts. The small, compact size and
offset connections make this kit
particularly easy to mount after
installing thermo-electric valves on
the manifold. It does not require a
larger or deeper zone box than
those used for normal manifolds.
Hydronic characteristics
By-pass differential pressure: 3.6 psi (2500 mm w.g.)
(psi) (mm w. g.)Δp (psi)
1
0.5
2
3
5
1000
500
2000
3000
4
1
0.5
2
3
5
4
1010
5000
500
200
1
000
Q (l/h) (
gpm
)
1
2
5
0.5
Technical specification
Materials: - body: brass
- nuts: brass
- pipe with plate: copper
- check valve: PA
- spring: stainless steel
- seals: EPDM
- gaskets: asbestos-free fibre
Medium: water, glycol solutions
Max. percentage of glycol: 50%
Max. working pressure: 150 psi (10 bar)
Temperature range: 14÷230°F (-10 to 110°C)
Fixed setting pressure: 3.6 psi (2500 mm w.g.)
Connections: 1/2” M x 1/2” M
Dimensions
A
B
5
3/8
” to 5
7/8
”
C
A
1/2"
C
1
3/8”
B
1/2"
Code
668000
Weight (lb)
0.74
Off-center differential by-pass assembly with fixed setting code 668000
Function
The distribution circuits of the heating fluid in radiant panel systems may be totally or partially shut off by closing the
thermo-electric valves inside the manifolds.
When the flow decreases, the differential pressure inside the circuit may rise to levels that could cause problems with noise,
high rates of fluid speed, mechanical erosion and hydronic imbalance of the system itself. The differential by-pass kit for
series 663 or 668S1 manifolds maintains the pressure of the supply and return manifold circuits in balance if the flow
changes.
The valve can be quickly connected to the series 663 or 668S1 manifolds, reducing overall size to a minimum.
Product range
Code 668000 Off-center differential by-pass assembly with fixed setting Size 1/2” M x 1/2” M
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