Bell & Gossett P86272B User Manual
INSTRUCTION MANUAL
P86272B
Model VS Variable Speed Pump Control
INSTALLER: PLEASE LEAVE THIS MANUAL FOR THE OWNER’S USE.
DESCRIPTION
The VS is a hydronic heating control. The temperature of the
SAFETY
INSTRUCTION
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.
heating water is controlled by regulating the speed of a pump
which injects water from a hot boiler loop (Primary loop) into a
cooler heating loop (Secondary loop). As the speed of the
pump increases, more hot water is sent into the Secondary
loop, and the temperature of the heating water increases.
The VS can be used as an outdoor reset control. When the
outdoor temperature falls below an adjustable start point, the
heating system is activated. The temperature of the Secondary loop water is then automatically regulated based on
outdoor temperature. The outdoor reset function maintains
constant and comfortable ambient building temperature in all
weather conditions.
The VS can also be used as a set point control. In this mode of
operation, the VS will control the pump speed to hold a constant temperature (determined by the user) in the Secondary
loop. The outdoor start temperature can be set to ON so the
set point will be held regardless of outside temperature.
The VS is equipped with a Primary loop sensor. This sensor
monitors the temperature of the boiler return water. If the
boiler return water falls below an adjustable temperature, the
VS can be configured to slow down the speed of the injection
pump to help the boiler return water temperatures recover.
The VS can be enabled or disabled from a standard thermostat
or switch, or the VS can reduce the temperature of the heating
loop water when the building is not occupied or when
occupants are sleeping.
REQUIREMENTS
ELECTRICAL SAFETY
WARNING: ELECTRICAL SHOCK HAZARD
Electrical connections are to be made by a qualified
electrician in accordance with all applicable codes, ordinances and good practices. Failure to follow these instructions could result in serious personal injury, death and/or
property damage.
VS
Outdoor
Sensor
Secondary Loop
Sensor
Boiler Return
Sensor
VS Pump
PRIMARY
LOOP
SECONDARY
LOOP
Boiler
Primary-Secondary Variable Speed Injection Mixing
Lower Temperature System
VS
Outdoor
Sensor
Secondary Loop
Sensor
Boiler Return
Sensor
VS Pump
PRIMARY
LOOP
SECONDARY
LOOP
Boiler
Primary-Secondary Variable Speed Injection Mixing
Multiple Temperature System
VS
Outdoor
Sensor
Secondary Loop
Sensor
Boiler Return
Sensor
PRIMARY
LOOP
SECONDARY
LOOP
Boiler
Primary-Secondary
Variable Load System
VS Pump
2
OPERATIONAL LIMITS
These controls are to be used with wet rotor pumps designed
to pump liquids compatible with their cast iron, bronze or
stainless steel body constructions.
Electrical Rating
VS Control: 115v, 60hz, 1Ø
Injection Pump: 115v, 60hz, 1Ø
Max. Rating 1/8 HP
Permanent Split Capacitor
Secondary Loop Pump: 115v, 60hz, 1Ø or 230v, 60hz, 1Ø
Max. Rating of 8 amps
TYPICAL APPLICATIONS (Fig. 1)
DESIGN SELECTION
To select the correct pump, pipe size and balance valve:
1.Determine the Primary Loop Temperature. This is the
temperature the primary loop will maintain.
2. Determine the Secondary Loop Temperature. This is the
design temperature of the secondary loop. If an outdoor
reset function is being employed, this is the required
temperature of the secondary loop under maximum load.
3. Determine the design temperature drop (
T or delta T) of
the secondary loop. This is the design drop in temperature through the secondary loop. In most radiant
heat applications,
T is 10. Other types of radiation such
as baseboard have a higher design
T.
4. Determine the Maximum Injection Heat Load. This is the
maximum heat requirement of the secondary loop. The
maximum injection heat load is based on the injection
pump running at the highest speed. As the pump speed
is reduced, less heat will be delivered to the secondary
loop.
5. Use the equation below to determine the design injection
flow rate.
Design Injection Flow Rate (GPM) =
Maximum Injection Heat Load (BTU/hr)
500 (T
primary - Tsecondary + Tsecondary) (ºF)
6. Use the table below to select the appropriate pump, pipe
size and balance valve.
Design Injection Injection B&G Circuit Setter
®
B&G Circuit Setter
®
B&G
Flow Rate (GPM) Pipe Size Balance Valve Valve Setting Pump
1.5
1
/2" CB-1/2 / CB-1/2S 18 / 25 NRF-22
3.5
1
/2" CB-1/2 / CB-1/2S full open / 6 NRF-22
6
3
/4" CB-3/4 / CB-3/4S full open / 12 NRF-22
10 1" CB-1 / CB-1S full open / full open NRF-22
15 11/4" CB-11/4 / CB-11/4S 5 / 5 NRF-22
24 1
1
/2" CB-11/2 full open NRF-33
Example:
1. Primary Loop Temp: 140ºF
2. Secondary Loop Temp: 100ºF
3. Design temperature drop: 10ºF
4. Maximum injection heat load: 150,000 BTU/hr
5. Calculate Injection flow rate
Design Injection Flow Rate (GPM) =
150,000 (BTU/hr)
=
150,000
= 6 GPM
500 (140 - 100 + 10) (ºF) 25,000
6. Injection Pipe size is
3
/4", full open CB-3/4 balancing valve and NRF-22
Minimum of 1' of
pipe drop required
to create a thermal
trap
Rule of Thumb
3 pipe diameters
between tees
Minimum of 8 pipe diameters upstream
and 4 pipe diameter downstream of straight
pipe on either side of tees to prevent any
possibility of “jet flow” through the
common piping.
Secondary
Loop
Secondary
Loop Pump
Primary
Loop Pump
Secondary
Loop Sensor
Boiler Return
Sensor
Primary
Loop
Injection Pump
Balance
Valve
3
FIG. 2
Based on (5) feet of pipe, (4) 90° elbows, (4) tees. Correct pipe and pump size calculation for any application should be performed by a qualified engineer or contractor.
PIPING
PIPING OVERVIEW
• The Primary loop may have multiple injection loops or other
takeoffs. However, the piping for each injection system
must meet the requirements described below.
• The Injection piping can be installed in either a horizontal or
a vertical configuration.
• The pipe diameters of the Primary and Secondary loops
may differ.
• The Injection Piping diameter must be at least one pipe size
smaller than the smaller of the Primary and Secondary loop
piping. For example, if the Primary loop diameter is 1
1
/4"
and the Secondary loop diameter is 1", then the diameter of
the Injection piping must be
3
/4" or smaller.
• The Injection pump motor must be a fractional B&G NRF,
NBF or SSF permanent split capacitor type pump. (Refer to
operational limits on Page 2 for pump information.) The
Injection pump will control the amount of water pumped
from the Primary loop into the Secondary loop.
• A balancing valve should be installed on the injection return
piping. This helps to balance the system.
• The distance between the injection tees should be as short
as possible. The rule of thumb distance between the tees is
3 times the pipe diameter. For instance, if the pipe diameter
is 1" then the length of straight pipe between the two
injection tees should be 3".
HORIZONTAL PIPING CONFIGURATION
• The Injection piping can be installed horizontally as shown
in Fig. 2.
• The Injection supply piping should run horizontally from the
Primary to the Secondary loop.
• On the Injection piping it is necessary to install a heat trap
to prevent heat from the Primary loop entering the Secondary loop when the Injection pump is not running.
• The injection piping must drop down vertically at least 18"
and then rise back up vertically at least 18".
VERTICAL PIPING CONFIGURATION
• The Injection piping can be installed vertically.
• The Primary loop must be at least 18" vertically above the
Secondary loop.
4
CAUTION: The Injection pump and pipe sizing
should be performed by a qualified engineer or
contractor.
Secondary
Loop Sensor
Secondary
Loop Pump
Outdoor
Sensor
BLUE
RED
BLACK
120 VAC
LINE NEU
Setback or
Remote Enable
L
O
A
D
Pump
Starter /
Motor
••
Pump
Motor
•
Injection
Pump
Boiler Return
Sensor
Boiler
••
Injection pump must be connected directly to 120VAC motor N.O. pump starter.
••
Secondary pump starter/motor can be 115V or 230V.
VS WIRING DIAGRAM (Fig. 3)
NOTE: Injection Pump and the VS Control MUST be
wired to the same power circuit. The secondary loop
pump can be wired to a different circuit if required.
Loading...