Installation, Operation, & Service Instructions
SAFETY
INSTRUCTIONS
This safety alert symbol will be used in this manual to draw
attention to safety related instructions. When used, the safety
alert symbol means ATTENTION! BECOME ALERT! YOUR
SAFETY IS INVOLVED! FAILURE TO FOLLOW THESE
INSTRUCTIONS MAY RESULT IN A SAFETY HAZARD.
DESCRIPTION
The Bell & Gossett DB differential by-pass valve is used in
systems where various heating loads may be simultaneously
excluded from the circuit because of the closing of control or
zone valves.
It ensures a recirculation proportional to the number of valves
which close, avoiding noises and maintaining the head of the
pump at a constant value.
TECHNICAL SPECIFICATIONS
Connections:
3/4" x 3/4" NPT Male
Materials: – Body
Brass
– Seals
EPDM
– Spring
Stainless Steel
– Knob
ABS
Medium:
Water and glycol solutions up to 50%
Maximum Working Pressure:
150 PSI (10 Bar)
Maximum Working Temperature:
230°F (110°C)
Maximum Flow Rate:
9 GPM
Adjustment Range:
2 to 10 PSI (0.15 to 0.7 Bar)
INSTALLATION INSTRUCTIONS
INSTALLER:
PLEASE LEAVE THIS MANUAL FOR THE OWNER’S USE.
DB-3/4"
Differential By-Pass Valve
3/4" x 3/4" NPT Male Connections
Operational Limits
Bell & Gossett
Instruction Manual A91590
REVISION A
Max. Temperature
230°F (110°C)
Max. Pressure
150psig (10 Bar)
NOTE: This product is not intended for use in potable
water applications.
WARNING: System fluids are under pressure or temp-
erature can be hazardous. Be sure the pressure has
been reduced to zero and the system temperature is below
100°F (38°C). Failure to follow these instructions could result
in property damage and/or personal injury.
WARNING: State of California Residents
This product contains a chemical known by the State
of California to cause cancer. This products contains a
chemical known by the State of California to cause birth
defects or other reproductive harm.
CAUTION: All work must be performed by qualified
personnel trained in the proper application, installation,
and maintenance of systems in accordance with all applica-
ble codes and ordinances.
