Mode 8
– This mode is for remote firing control of the
heater via an external sequencer such as the Raypak
TempTracker MOD+. The Boil Max setting is the
heater shutdown temperature (max temperature). The
heater is enabled via dry contact at the Enable/Disable
connection at the low voltage terminal strip, and the fir-
ing rate is controlled by a 0-10 VDC signal from the
external sequencer. A control signal of ≥0.5 VDC
equates to minimum fire, and a signal of 10 VDC
equates to 100% firing rate.
Definitions
% OUT
- Current percent modulation rate of heater.
BOIL DSGN
- Design boiler water temperature used in
heat loss calculations.
BOIL MASS
- This setting allows adjustment in the
field for high or low thermal masses; High thermal
mass (setting=3) provides slower reaction, lower ther-
mal mass (setting=1) provides faster reaction.
BOIL MAX
- Highest outlet water temperature that the
control is allowed to use as a target temperature.
BOIL MIN
- Lowest outlet water temperature that the
control is allowed to use as a target temperature.
33
2-10 VDC
4-20 mA*
Boiler Target
0
0
--- (OFF)
1
2
--- (OFF)
2
4
50°F
3
6
71.3°F
4
8
92.5°F
5
10
113.8°F
6
12
135°F
7
14
156.3°F
8
16
177.5°F
9
18
198.8°F
10
20
220°F
Table P: 2-10 VDC or 4-20 mA External Input Signal
*Requires a 500Ω resistor.
NOTE:
The defined terms are not active in all
modes of control operation.
BOIL ON
- Accumulated runtime of heater (up to 999
hours, then resets to 0).
BOIL OUT
- Actual heater outlet water temperature.
BOIL START
- Starting boiler water temperature.
BOIL SUP
- Actual system supply water temperature.
BOIL TARGET
- Target temperature that the heater is
trying to maintain.
‘BURNER’ DELAY
- Holds control output at ignition
setting from the start of the ignition sequence to the
specified burner delay time (0 to 3:00 min.).
DEM 1
- Indicates 24 VDC signal has been supplied to
the H+D terminal.
DEM 2
- Indicates 24 VDC Flame Proof signal is pres-
ent.
DIFF
- The operating differential of the heater; The
heater outlet water temperature is allowed to rise
above the BOIL TARGET temperature by
1
⁄
2
of this dif-
ferential before the heater shuts off. For example, if
the heater target temperature is set to 160°F (71°C)
and the differential is set to 10°F (5°C), on temperature
rise, the heater will shut off at 165°F (74°C). Once the
heater shuts off, it will not come on again until the tem-
perature falls to 155°F (68°C).
*
RAYPAK
MODULATING
TEMP CONTROL
OUTDOOR AIR
SENSOR
*Maximum 4 times the pipe diameter or 12”, whichever is less.
Fig. 36: Mode 8 Primary/Secondary Piping with
External Direct Drive
NOTE:
For Modes 7 and 8, connect to pins 13 and
14 on the low-voltage panel. See page 21. Use
these modes for systems using an external signal.