Bell & Gossett P86271B User Manual
INSTRUCTION MANUAL
P86271B
Variable Speed NRF-VS Control with
setpoint or external signal follower
INSTALLER: PLEASE LEAVE THIS MANUAL FOR THE OWNER’S USE.
WARNING
SAFETY
INSTRUCTION
This safety alert symbol will be used in this manual and on the
pump Safety Instruction decal 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.
Your NRF-VS Control should have the warning/caution label
displayed to the right (Fig. 1) on the pump conduit box. If this
warning and caution label is missing or illegible, contact your
local B&G Representative for a replacement.
FIG. 1
BEFORE INSTALLING,
USING OR SERVICING
THIS PRODUCT, READ
THE INSTRUCTIONS
TO REDUCE RISK OF
ELECTRICAL SHOCK, SEE
INSTRUCTIONS FOR
PROPER INSTALLATION.
CAUTION
FOR SUPPLY CONNEC-
TIONS USE WIRE SUITABLE FOR AT LEAST
90ºC. USE COPPER
CONDUCTORS ONLY.
EMPLOYER DES FILS
D’ALIMENTATION
ADEQUATS POUR 90°C.
FOR INDOOR USE ONLY.
EMPLOYER UNIQUEMENT
AL’INTERIEUR.
REQUIREMENTS
ELECTRICAL SAFETY
TYPICAL APPLICATIONS
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.
WARNING: ELECTRICAL GROUNDING HAZARD
Adequate electrical grounding is required for the safe
operation of B&G Pumps. The use of grounded metal conduit assures this requirement. If means of connection to the
supply – connection box (wiring compartment) is other than
grounded metal conduit, ground the pump back to the
service. Use a copper conductor at least the size of the
circuit connectors supplying the pump. Connect the ground
wire to the green grounding screw in the wiring compartment. Failure to follow these instructions could result in
serious personal injury, death and/or property damage.
PRIMARY-SECONDARY WITH FAN COIL
PRIMARY
LOOP
Boiler
NRF-VS
Building
Management System
Boiler
Boiler
Sensor
NRF-VS
BYPASS BOILER INJECTION
Secondary Loop
Sensor
SECONDARY
LOOP
NRF-VS
PRIMARY
LOOP
Boiler
PRIMARY-SECONDARY INJECTION
SECONDARY
LOOP
PRIMARY
LOOP
Boiler
PRIMARY-SECONDARY
NRF-VS
Variable Speed
Control or Building
Management System
2
DESCRIPTION
The NRF-VS is a variable speed control for use in hydronic
heating and cooling applications. The temperature of the
water is controlled by regulating the speed of the pump which
injects water from a different temperature water loop (Primary
loop) into a controlled loop (Secondary loop). As the speed of
the pump increases, more water is sent into the Secondary
loop, resulting in a secondary loop water temperature change.
The NRF-VS can be used either to receive an external 4-20mA
or 2-10V signal to control the pump speed. This allows the
control to regulate the pump speed to match the input signal
supplied.
The NRF-VS can also be used as a set point control. In this
mode of operation, the NRF-VS will control the pump speed to
hold a constant temperature (determined by the user) in the
Secondary loop. The NRF-VS is capable of reading the loop
temperature sensor. When used in a heating application, if
the loop temperature falls below an adjustable setting, the
NRF-VS will increase the speed of the injection pump.
In addition, the NRF-VS can be used in cooling applications. In
this senario, the NRF-VS wil increase pump speed whenever
the loop temperature increases above the setpoint.
OPERATIONAL LIMITS
These controls are to be used on pumps designed to pump
liquids compatible with their cast iron, bronze or stainless
steel body constructions.
Maximum Operating Pressure: 150 PSI (10 bars).
Maximum Operating Temperature: 240ºF cast iron body,
230ºF brass and stainless steel body.
Electrical Rating: 115V, 60HZ, 1Ø.
Suitable for NRF, NBF, and SSF pumps with less than 1.1
amps pump nameplate rating.
OPERATION
The NRF-VS is designed to control the pump speed on an
injection system allowing the pump to inject a different water
temperature into a secondary loop to regulate its temperature.
It can be used either in heating or cooling applications using a
secondary loop temperature sensor. The sensor reads the
secondary loop temperature allowing the NRF-VS to regulate
the loop temperature by modulating the injection pump speed
accordingly to reach a set point.
A temperature knob mounted on the NRF-VS is used to adjust
the temperature set point either in heating or cooling (see Dip
Switch 2). Dip Switch 1 must be set to ON to activate the Set
Point feature. The sensor must be wired to terminals 2 and 3
when using the setpoint mode.
The NRF-VS can be controlled remotely using an external
signal to replace the set point. This allows for the external
control or system providing the input to change the pump
speed directly. No sensor is required in this setting. The
external input providing either 4-20mA signal or 2-10V signal
must be wired to terminals 1 and 2. The speed of the pump
will vary from full stop below 4mA or 2V to 100% at 20mA or
10V. Dip switch 1 must be set OFF to activate the external
signal feature.
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 1
1
/4" CB-11/4 / CB-11/4S 5 / 5 NRF-22
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
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.
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