Bell & Gossett P86272B VS Variable Speed Pump Control - Manual (Page 12)

Insufficient Heat when the OUTPUT light is ON
(Reset Operation):
Check all the settings. If the Boiler Return (
rtn) sensor reading
is below the Low Return ( LOr ) setting the VS will halve the
speed of the Injection pump until the boiler return
temperatures recover. The temperature of the Secondary loop
will never exceed the High Supply (
HI ) setting for any
prolonged period of time. Check that the High Supply ( HI ) is
not set too low. Check if the VS is in Setback and therefore
running lower water temperatures. If none of these conditions
are causing insufficient heat, then adjust the Reset Ratio (
rSt )
or Offset (
OFS ) (see pg. 10).
Insufficient Heat when the OUTPUT light is ON
(Set Point Operation):
Check all settings. If the Boiler Return (
rtn) sensor reading is
below the Low Return ( LOr ) setting (see above) the VS will
halve the speed of the Injection pump until the boiler return
temperatures recover. Check if the VS is in Setback and
therefore running lower water temperatures. If neither of these
conditions are causing insufficient heat, then increase the Gain
(
GAn) (see pg. 11).
SENSORS
Each of the three VS sensors are interchangeable and can be
tested in the same way. If the Secondary loop sensor is open
or shorted, the main display will show
OPn or SHt. If either the
Outdoor or the Boiler Return sensor is open or shorted, the
display will first flash the code for the sensor (either
SEC or
rtn) and then flash OPn or SHt. To test the sensor, remove the
pair of sensor wires connected to the VS terminals. Take a
resistance reading across the detached wires going to the
sensor. If the reading shows:
OPEN OPn or a resistance greater than 100,000�: Check
the wires going to the sensor. They may have been broken or
become disconnected. If the wires are fine, check the
resistance at the sensor itself. If the value is still open, the
sensor has been damaged and needs to be replaced.
SHORT SHt or a resistance less than 100�: Check the wires
going to the sensor. They may have become shorted together
in the run of the wire. If not, check the resistance at the sensor
itself. If there still is no resistance, the sensor has been
damaged and needs to be replaced.
Resistances from 200� to 100,000�: Find the temperature
that corresponds to the resistance value on the chart. If the
sensor appears to be outputting correctly, check that the
wires were properly connected to the VS. If they were, the VS
may have been damaged. If the sensor is not outputting
correctly, take another reading at the sensor itself. If this is
correct, the problem is in the wiring between the sensor and
the VS. Otherwise, the sensor has been damaged, and should
be replaced.
PERIODIC INSPECTION
Bell & Gossett products are designed to provide years of
trouble free service. It is recommended that periodic inspec-
tions be made to check for potential problems with the pump
and control. If any leakage or evidence of leakage is present,
repair or replace the unit.
TEMPERATURE Value
(in Degrees ºF) (in 0hms)
-30 117720
-20 82823
-10 59076
0 42683
10 31215
20 23089
25 19939
30 17264
35 14985
40 13040
45 11374
50 9944
55 8714
60 7653
70 5941
80 4649
90 3667
100 2914
110 2332
120 1879
130 1524
140 1243
150 1021
160 842
170 699
180 583
190 489
200 412
210 349
220 297
230 253
240 217
250 187
WARNING: The VS is an operating control only. The
boiler must have all safety and limit controls required
by code. It is the responsibility of the installer to verify that
all the safety and limits are working properly before and
after the VS is installed. Failure to follow these instructions
could result in serious personal injury, death and/or
property damage.
TEMPERATURE
SENSOR CHART
Xylem Inc.
8200 N. Austin Avenue
Morton Grove, Illinois 60053
Phone: (847) 966-3700
Fax: (847) 965-8379
www.xyleminc.com/brands/bellgossett
Bell & Gossett is a trademark of Xylem Inc. or one of its subsidiaries.
© 2012 Xylem Inc. P86272B May 2012