Weil-McLain Aqua Balance WMB-155 Manual page 64

W
TM
AquaBalance
26 Controls and operation
Adjustments for - Heating Only Boilers
with Outdoor sensor
Optional for Combi with Outdoor sensor
Theory of Outdoor Reset Control
One of the key points to boiler efficiency, is to match the
heat generated by the boiler to the heat loss of the building
to be able to obtain a given comfort level in the living space.
• You can obtain this efficiency by selecting a scale within an
operating programmed range of the boiler water tempera-
ture. These scale ranges are related to the outdoor tempera-
tures, and boiler water temperatures for the installed radiation.
• These "Outdoor Reset Control" curves are graphed (and pro-
grammed into the control board) by outside temperature from
68 degrees to -4 degrees F and boiler water target tempera-
tures from 86 to 194 degrees F (see Figure 86, page 65), where
the heat loss of the home, will match the gradual increase in
boiler water temperature as the outside temperature drops.
• The average heat loss of a home may meet the needs (boiler wa-
ter temperatures) of offset curve number 6 (Figure 88, page 65)
to meet the heat loss at given outdoor temperatures.
• Another example would be a high heat loss structure, where
curve number 10 would drive up the boiler water temperature
with a slight drop in outdoor temperature. (from 68 degrees
F outside temperature to just a drop to 50 degrees F outdoor
temperature, see Figure 88, page 65).
• An example of a structure with very little heat loss, (such as
a super insulated, high efficiency building) would be curve
number 1, where the outdoor temperatures continue to drop,
and the boiler water temperatures are in the low range from 86
degrees to 104 degrees F.
Outdoor Reset Control (optional on the Combi)
1. When the external outdoor sensor is attached to the boiler,
the system can work in Outside Temperature Compensation
mode. In OTC mode the temperature of the heating system
is controlled according to the external climate conditions,
this will insure a high degree of comfort and energy saving
all year round.
2. By using the CH buttons (Items 3 and 4 - Figure 84) it is pos-
sible to set the maximum system water flow temperature for
the installation.
OTC setting - Heating Only with sensor
1. To enter the OTC - reset mode, press "reset" button for 5
seconds, takes you to Curve menu.
2. The display shows "CU" flashing Figure 84; to set Curve, use
the DHW buttons (Items 1 and 2 - Figure 84) pushing CH +
or - buttons switches your screens between CU (Curves) or
OF (Offset). Display "CU" allows Curves value adjustment,
value can be varied from 1 to 10, in accordance with the
charts on page 65. "O" means no OTC mode.
3. By pressing the CH push buttons (Items 3 and 4 - Figure 84,
the display shows "0F" flashing Figure 85; to set Offset, use
the DHW push buttons (Items 1 and 2 - Figure 84).
64
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ALL OUNT GAS FIRED WATER BOILER
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Boiler Manual
(continued)
Figure 84 OTC settings
DHW
1 2
3 4
4. It can be 68 to 104, in accordance with the chart Figure 87
or Figure 88, page 65.
5. To exit the OTC mode, press OTC button "reset" button for
5 seconds.
Figure 85
OTC "OFFSET" settings
CH
In the case of an outdoor sensor failure,
will continue to operate the boiler, but without the use of
the Compensation Curves, and an error message will flash
on the display (Fault 39 -please see Figure 117, page 93).
Upon replacement of the defective sensor the boiler will re-
sume the use of Compensation Curves .
OTC Exempt mode
By pressing the DHW+ and eco buttons together for 10 sec-
onds, it is possible to enter the OTC Exempt menu. The display
starts showing the value of the parameter OTC Exempt (See
parameter Number 163, page 105) flashing. By means of the
CH - push button it is possible to change value.
(Selecting 0 - allows you to Select the Compensation curve for
your individual home heating needs). By pressing DHW+ and
eco
buttons together for 10 seconds, it is possible to leave the
OTC Exempt Menu. If no action has been taken, the control
automatically leaves this mode after 2 minutes.
- 0 = installation non exempt from outside sensor connection;
- 1 = installation exempt for outside sensor connection;
Compensation curves - Heating Only
Curve numbers below refer to Figures 86, 87, & 88, page 65.
• Curve number 1 is for a high efficiency home with very
low heat losses.
• Curve number 6 is for an average home heat losses.
• Curve number 10 is for a home with high heat losses.
eco
OTC/reset
OTC/RESET
the control
Part number 550-100-305/0118