Weil-McLain WM97+70 Specifications download pdf (Page 78)

Part number 550-142-120/0113

WM97+ gas-fired water boiler — Boiler Manual

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HEAT SETTINGS menus (continued)

HEAT SETTINGS

1. The heat settings menus are for setting control operation during

space heating. The settings apply to all space heating zones. See Fig-

ure 89, page 79 for a listing of menu listings.

2. If DHW is used, the settings for control operation during DHW calls

is set under the DHW SETTINGS menus (see Figure 90, page 80).

SYSTEM TYPE

1. Select the appropriate system type, based on the heating terminal units

in the system. Use the CUSTOM selection to set the WM97+ control

for a different system type.

2. The temperature presets are chosen based on normal best setting for

the terminal units. The temperature values can be changed, if desired,

under “TEMPERATURES.”

BOILER CIRCULATOR SPEED

1. The boiler circulator speed can be chosen as needed for the ﬂow re-

quirements of the installation.

PRIMARY/SECONDARY operation (boiler internal by-pass

valve OPEN) — For most applications operating as primary/

secondary, set the boiler circulator speed to LOW. If the

temperature rise through the boiler is not acceptable at this

ﬂow, increase the speed to MED. Temperature rise should

preferably be 30°F.

2. The LED on the circulator ﬂashes based on speed (on constantly at

high speed).

TEMPERATURES (HEATING DESIGN

TEMPERATURES)

1. Set desired temperatures for space heating zones.

2. For an explanation of the target temperatures and associated outdoor

temperatures, see Figure 88.

MAX SUPPLY

1. Set MAX SUPPLY to the required supply water temperature for the

system at design maximum heat loss (typically 180°F for ﬁnned tube

baseboard on new installations).

MIN SUPPLY

1. MIN SUPPLY should equal the desired minimum supply water tem-

perature for the system.

2. The factory default is 130°F. This could be set as low as 70°F, which

would supply “zero heat” when outdoor temperature is 70°F, because

supply water temp would equal room temp.

3. See examples in Figure 88.

MAX OUTDOOR

1. MAX OUTDOOR means the outdoor temperature at which the target

temperature reaches its minimum (MIN SUPPLY).

2. In the example of Figure 88, this occurs at 70 °F (the factory default).

MIN OUTDOOR

1. MIN OUTDOOR means the outdoor temperature at which the target

temperature reaches its maximum value (MAX SUPPLY).

Figure 88 Typical outdoor reset curves

2. In the example of Figure 88, this occurs at 0°F

outside (the factory default setting).

3. MIN OUTDOOR should equal the ODT (outdoor

design temperature) for the installation’s location.

MODULATE ON DIFF

1. The temperature must drop this many degrees

below target temperature for the boiler to come on

when a call for heat is present.

MODULATE OFF DIFF

1. While the boiler is ﬁring, as the temperature in-

creases above the target temperature, the boiler

ﬁring rate is reduced.

2. At this many degrees above the target temperature,

the boiler shuts down.

TIMES (HEATING TIMES)

MIN ON TIME

1. This is the minimum time the boiler will satisfy the

call for space heating before switching to DHW (if

there is a DHW call).

BOOST INTERVAL

1. This applies when in outdoor reset mode (outdoor

sensor installed — see page 133).

2. The boost timer starts on a call for heat. If the boost

interval time passes and the call for heat is still on,

the WM97+ control “boosts” the calculated target

outlet water temperature by 10°F.

3. This occurs again if another boost interval elapses.

CONTINUED ON NEXT PAGE

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Weil-McLain WM97+70 Specifications Page 78

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