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Part number 550-100-325/0419
66
AquaBalance
®
Series 2 Wall Mount Gas-fired Water Boiler – Boiler Manual
27 Controls and operation (continued)
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 90, page 67), 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 92, page 67)
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 92, page 67).
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
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 88) it is pos-
sible to set the maximum system water flow temperature for
the installation.
OTC setting - with Outdoor 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 88; to set Curve, use
the DHW buttons (Items 1 and 2 - Figure 88) 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 67. “O” means no OTC mode.
3. By pressing the CH push buttons (Items 3 and 4 - Figure 88,
the display shows “0F” flashing Figure 89; to set Offset, use
the DHW push buttons (Items 1 and 2 - Figure 88).
Figure 88
Figure 89 OFFSET
4. It can be 68 to 104, in accordance with the chart Figure 91
or Figure 92, page 67.
5. To exit the OTC mode, press OTC button “reset” button for
5 seconds.
In the case of an outdoor sensor failure, the control
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 122, page 97).
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 109) 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
Curve numbers below refer to Figures 90, 91, & 92, page 67.
Curve number 1 is for a high efficiency home with very
low heat losses. (Least aggressive curve).
Curve number 6 is for an average home heat losses.
Curve number 10 is for a home with high heat losses.
(Most aggressive curve).
CH
OTC/RESET
DHW
OTC/reset
1
2
3
4
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