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If WWSD is not activated and the inlet sensor is ½ (half) of
the differential below the calculated BOIL TARGET, the
BTC 1 then changes the modulation output to the START
modulation setting and closes the Stage contacts (pins 15
& 16) to proceed to trial for ignition. The burner remains at
minimum modulation until the flame is proved and then
modulating output changes the boiler output to maintain the
calculated boiler target temperature at the inlet sensor. If
the inlet sensor reaches ½ (half) of the differential above
the BOIL TARGET, the appliance is shut off. The boiler
pump continues to circulate until the PUMP DELAY timer
expires.
The water temperature is controlled based on a calculated
boiler target temperature. The boiler start (BOIL START)
temperature is pre-set to 70
set to 210° F and is fixed. In addition to the auto reset limit
the factory installs a manual re-set limit set to 250° F.
Figure 27: Mode 4 Piping & Electrical Layout
Mode 5:
Outdoor Reset using System Sensor
This mode is designed for hydronic heating. Once a heat
demand is present, the BTC 1 turns on the appliance pump
and modulates the boiler to maintain the calculated outdoor
reset target at the system sensor. Outdoor reset calculates
the boiler target temperature based on the outdoor air
temperature and reset ratio.
A heat demand is generated when a voltage between
24VAC and 120VAC is applied across CD (common
demand) and Ht D (heat demand). Once voltage is applied,
the BTC 1 turns on the Dem 1 segment in the display. If
warm weather shut down (WWSD) is activated, the WWSD
segment is lit.
If WWSD is not activated and the system sensor is ½ (half)
of the differential below the calculated BOIL TARGET, the
control then changes the modulation output to the START
modulation setting and closes the Stage contacts (pins 15
&16) to proceed to trial for ignition. The burner remains at
minimum modulation until the flame is proved and then the
modulating output changes the boiler output to maintain the
calculated boiler target temperature at the system sensor. If
the system sensor reaches ½ (half) of the differential above
the BOIL TARGET, the appliance is shut off. The appliance
pump continues to circulate until the PUMP DELAY timer
expires. In this case, it is imperative that the system pump
operates continuously in order to provide constant
circulation past the system sensor.
The water temperature is controlled based on a calculated
boiler target temperature. The boiler start (BOIL START)
temperature is pre-set to 70
set to 210° F and is fixed. In addition to the auto reset limit
the factory installs a manual re-set limit set to 250° F.
27
o
F and the auto re-set limit is
o
F and the auto re-set limit is
Figure 28: Mode 5 Piping & Electrical Layout
Mode 6:
External Target Temperature using Boiler Inlet
Sensor
The external input signal can be provided from a BMS,
EMS or a tekmar tN4 System Control. The external input
signal creates an internal demand and changes the boiler
target according to a linear scale. The BTC 1 modulates the
boiler to maintain the boiler target at the inlet sensor.
An internal heat demand is generated when an analog
positive 2-10VDC signal is applied to the +V input and a
negative DC signal is applied to the Com/- input.
The following table shows the various signals required to
generate various Target temperatures.
Table 12: External Signal Cross Reference Chart
4-20
mA
Boiler Target
0
- - - (OFF)
2
- - - (OFF)
o
o
4
50
F (10
C)
o
o
6
70
F (21
C)
o
o
8
90
F (32
C)
o
o
10
110
F (43
C)
o
o
12
130
F (54
C)
o
o
14
150
F (66
C)
o
o
16
170
F (77
C)
o
o
18
190
F (88
C)
o
o
20
210
F (99
C)
* requires 500 resistor
A 4-20mA signal can be converted to a 2-10VDC signal by
installing a 500 resistor on the external input signal
device's terminal.
If the inlet sensor is ½ (half) of the differential below the
Boiler Target, the BTC 1 then changes the proportional
modulation output to the START modulation setting, the
Stage contact (pins 15 & 16) closes to proceed to trial for
ignition. The burner remains at minimum modulation until
the flame is proved and then the modulating output
changes the boiler burner output to maintain the
programmed boiler target temperature at the inlet sensor. If
the inlet sensor reaches ½ (half) of the differential above
Boiler Target, the burner shuts off. Once the external heat
demand is removed, the BTC 1 turns off the appliance and
operates the boiler pump based on the PUMP DELAY
setting.
0-10V
(dc)*
Boiler Target
0
- - - (OFF)
o
o
1
50
F (10
C)
o
o
2
68
F (20
C)
o
o
3
86
F (30
C)
o
o
4
103
F (39
C)
o
o
5
121
F (49
C)
o
o
6
139
F (59
C)
o
o
7
157
F (69
C)
o
o
8
174
F (79
C)
o
o
9
192
F (89
C)
o
o
10
210
F (99
C)
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