Proheat X45–School Bus - Manual (Page 39)

PROHEAT INSTALLATION & SERVICE 3-18
These installation options allow the operator to:
1. Run the PROHEAT in Preheat Mode or Supplemental Mode alone.
2. Run the PROHEAT in the Preheat and Supplemental Mode.
3. Run the PROHEAT in Standard Mode (Proheat Timer option) and using the
Supplemental Mode.
In addition to the Standard Operating Mode, there are two other operating modes:
Preheat and Supplemental. One operating mode is for one button preheating
the engine and the second is for supplemental heat while the vehicle is being
operated. The benefits include easier operation for the driver; simplified
installation; eliminates need for extra control relays; and increases reliability
by reducing unnecessary heater operation.
The feature that makes this Auxiliary Input Model unique is that the PCM
(Proheat Control Module) has three inputs to turn the heater on; one for each
operating mode. The following is a description of the three operating modes.
Standard Heat Mode
Coolant temperature is monitored via a built in sensor. When the temperature at
the Proheat is below 150° F (65° C) * the Proheat operates, heating the coolant to
185° F (85° C) at which point it stops burning fuel and goes into Standby with
only the coolant pump running. Standard Heat Mode is typically activated by
use of a toggle switch which must be manually switched off. If the switch is not
turned off the heater will continue to run overnight. Since the coolant pump
runs continuously in this mode, It is possible to accumulate a high number of
coolant pump operating hours vs heater run hours. Use of supplemental mode
is recommended in conjuction with standard mode in many cases.
Supplemental Heat Mode
The amount of heat required varies depending on engine load, outside temperature,
frequency of door opening, etc. Recognizing this varying demand for heat, the
Proheat monitors the conditions and supplies heat only when required. When
heat is not required, the Proheat puts itself into supplemental standby, shutting
off the coolant pump, thereby avoiding additional run hours on the pump. This
is ideal for transit and coach applications.
In order to simplify operation, this function is fully automatic and invisible to
the operator. The Proheat picks up a signal that the engine is running, and then
monitors the coolant temperature via a built-in sensor. If the coolant temperature
at the Proheat is below 150° F (65° C) * the coolant pump is activated for three
minutes * . This causes coolant in the engine to be circulated through the Proheat.
If after three minutes * the coolant temperature is above 150° F (65° C) * , the
Proheat will turn off the coolant pump and return to supplemental standby. If
the coolant temperature remains below 150° F (65°C) * , the Proheat will operate
and continue to supply heat to the system until the coolant temperature reaches
185° F (85° C). The Proheat then shuts itself off, returns to supplemental
standby, deactivates the coolant pump and waits for the coolant temperature
to fall below 150° F (65° C) * , and the cycle is repeated.
The Proheat switches off when the engine stops, thus avoiding the problem
of the driver forgetting to switch the unit off and leaving it running overnight.
AUXILIARY INPUT MODEL HEATER WIRING DETAILS 3.5.10
NOTICE
These instructions require a Auxiliary
Input model. For more information see
page 4-2.
NOTICE
The Preheat and Supplemental modes
are generally used by transit and
coach applications.
NOTICE
The PROHEAT must have coolant
flowing through it when it is
monitoring temperature.
NOTICE
Supplemental operation will not override
the Standard Mode operation (Proheat
Timer runs in Standard Mode).