Introduction
©Aqua-Hot®
250-D03 Diesel Series Service Manual
REV 220302
p. 2
Contents
Caution Notes ...............................................................................2
Introduction ..................................................................................3
Maintenance Schedule ................................................................5
System Features ..........................................................................6
Component Cut-Away ...................................................................7
Operational Flowchart..................................................................8
Operating the Aqua-Hot ..............................................................9
Aqua-Hot Controller ....................................................................11
Exhaust System ......................................................................... 18
Interlock Switch ..........................................................................19
Fluid Level Sensor ..................................................................... 20
ETS Module ............................................................................... 22
AC High-Limit Thermostat ..........................................................24
Burner High-Limit Thermostats ................................................ 26
Low-Temperature Cutoff Thermostat........................................27
Three-Way Valve ........................................................................ 29
Tempering Valve .........................................................................31
Fluid Circulation and Stir Pump ............................................... 32
AC Electric System..................................................................... 34
AC Relay ..................................................................................... 36
Diesel Burner ������������������������������������������������������������������� 37
Diesel Burner Operation ...................................................... 43
Detaching the Diesel Burner ................................................47
Reattaching the Diesel Burner............................................ 50
Diesel Burner Components ��������������������������������������������� 53
Diesel Burner Motor ............................................................ 53
Flame Sensor ........................................................................57
Ignition Electrodes ............................................................... 59
Ignition Coil ...........................................................................61
Fuel Nozzle ........................................................................... 62
Fuel Solenoid ....................................................................... 64
Fuel Pump ............................................................................ 65
Bearings ............................................................................... 68
Diesel Burner Controller .......................................................71
Checking Fuel Pressure ....................................................... 73
Adjusting Fuel Pressure ........................................................76
Annual Maintenance ........................................................... 78
Cold Weather Operation ........................................................... 90
Fill and Purge Procedure ...........................................................91
Winterization.............................................................................. 92
General Troubleshooting........................................................... 93
Lack of Hot Water ................................................................ 93
Lack of Heat ......................................................................... 94
Blue/White Smoke............................................................... 95
Black Smoke ........................................................................ 95
Caution Notes
As you read this information, take particular note of the NOTICE,
CAUTION, WARNING, and DANGER symbols when they appear.
This information is important for safe and efficient use of the
Aqua-Hot system.
NOTICE
signals a situation where potential damage to the
Aqua-Hot could occur.
CAUTION
signals a situation where potential harm or risk
of minor or moderate injury could occur if you do not follow
instructions.
WARNING
signals a hazardous situation where potential harm,
risk of serious injury, or death could result if instructions are
not followed.
DANGER
signals a situation where immediate risk of serious
injury or death will result if instructions are not followed.
NOTE:
This manual will also use notes sections similar to
this one to draw attention to features and practices which
must be observed.
Burner Troubleshooting ............................................................ 96
System Schematics ....................................................................97
Measuring Antifreeze .............................................................. 101
Antifreeze Information ............................................................ 102
Warranty .................................................................................. 104