Specifications

Part number 550-142-120/0113
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WM97+ gas-fired water boiler — Boiler Manual
DHW SETTINGS menus (continued)
Figure 91 DHW SETTINGS menus (see Figure 84, page 74 for access information)
Menu/Item Units
Low
Value
High
Value
Default Comment
DHW: Selection Off On Off This setting must be ON to operate in DHW mode
Boiler Supply °F 60 190 190 Boiler enters manual reset lockout at 200°F
Boiler Circulator Spd Selection Off High Off Select speed or select OFF to deactivate boiler during
space heating call
Modulate On Diff °F 2 10 5 Boiler turns on if temperature drops below target minus
differential on
Modulate Off Diff °F 2 10 5 Boiler shuts down if modulates past target plus differential
off
Max On Time minutes off 240 30 Longest time boiler will satisfy this system before switching
to DHW
Prepump Time: ###
SEC
seconds 0 240 20 Additional time to run circulators longer than standard 10
second time
Postpump Time: ###
SEC
seconds off 240 30 Circulator run time after call for heat ends
Maximum Rate
WM97+70
WM97+110
WM97+155
RPM
RPM
RPM
1100
1400
1300
4300
5650
5500
4150
5450
5300
Boiler Model and altitude specific
(derated automatically if HIGH ALTITUDE is selected in
control setup)
NOTE: Adjusting boiler firing rate will affect AFUE rating.
Minimum Rate
WM97+70
WM97+110
WM97+155
RPM
RPM
RPM
1100
1400
1300
4300
5650
5500
1100
1400
1300
Boiler Model and altitude specific
(derated automatically if HIGH ALTITUDE is selected in
control setup)
NOTE: Adjusting boiler firing rate will affect AFUE rating.
TEMPERATURES (DHW)
DHW priority — The WM97+ control gives priority
to DHW operation. During DHW call for heat, the
space heating zone ouputs (Zone 2 and Zone 3) are
disabled. This continues until the DHW call ends
or the DHW MAX ON TIME has elapsed.
BOILER SUPPLY
1. The WM97+ control will regulate boiler firing to provide
outlet water at this temperature.
2. For most DHW applications, set this to 190°F. A lower supply
temperature can be used, but will reduce the indirect water
heater heating capacity.
BOILER ON DIFF
1. The temperature must drop this many degrees below target
temperature for the boiler to come on.
BOILER OFF DIFF
1. While the boiler is firing, as the temperature increases above
the target temperature, the boiler firing rate is reduced.
2. At this many degrees above the target temperature, the control
will temporarily turn off burner. The burner will be restarted
when temperature drops below TARGET TEMPERATURE
minus BOILER ON DIFF.
CWH Installations — See Companion Water Heater manual for
control settings information.
TIMES (DHW TIMES)
MAX ON TIME
1. This is the longest time the boiler will continue in DHW
mode before switching to space heating (if there is a space
heating call).
Setting MAX ON TIME to off will cause the control
to never switch to space heating while DHW call for
heat is present. This could present a freeze hazard
for some installations if the DHW aquastat were to
remain closed indefinitely.
PRE PUMP TIME
1. The boiler circulator (if enabled) and DHW circulator will
start this amount of time before the burner is started.
POST PUMP TIME
1. The boiler circulator (if enabled) and DHW circulator will
continue this amount of time after the burner is shut down
when the call for heat is satisfied.
MIN RATE / MAX RATE
1. Use to set minimum and maximum boiler inputs by setting
minimum and maximum blower RPM.