Raypak MVB 5042004 - Manual (Page 33)

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.