1
PART 1
GENERAL
INFORMATION
1.1
INTRODUCTION
The TH Series is a fan assisted heater based on a push
through design which offers several venting options. Heat
output is controlled by a one to one air/gas ratio control gas
valve which provides seamless modulation. The heater
provides domestic hot water at working pressures up to 160
PSI. It is designed for use with a fully pumped and
pressurized water system. The water heater will
automatically modulate to provide heat outputs from 100%
down to approximately 20% of rated input.
The TH utilizes a negative pressure gas valve. The
operation of the fan will generate a negative pressure in the
venturi, which draws in a matching amount of gas through
the valve.
During operation the TH maintains a steady state efficiency
across the entire range of modulation. Air and gas are
metered in precise proportion (1:1 Ratio) allowing
combustion characteristics which determine efficiency to
remain the same over the entire operating range.
The TH is designed so that all of the sensible heating value
and most of the latent heat is being transferred to the water.
1.2
SPECIAL INSTRUCTIONS TO OWNER
This manual supplies information for the installation,
operation and servicing of the appliance. It is strongly
recommended that this manual be reviewed completely
before proceeding with an installation
CAUTION
It is important that all gas appliances are installed by a
qualified installer/technician that is trained by Camus
Hydronics. It is in your own interest and that of safety to
ensure that all local codes, and all the following “NOTES”
and “WARNINGS” are complied with.
Installing, servicing or adjusting this appliance should be
performed only by a qualified installer/technician that is
trained by Camus Hydronics. The serviceman must utilize a
combustion analyzer with CO
2
, CO to set the appliance
according to Camus Hydronics’ recommendations, prior to
commissioning.
NOTE
RETAIN THIS MANUAL FOR FUTURE REFERENCE
1.3
CHECKING EQUIPMENT
Check for signs of shipping damage upon receiving
equipment. Pay particular attention to parts accompanying
the boiler, which may show signs of being hit or otherwise
being mishandled. Verify total number of pieces shown on
packing slip with those actually received. In case there is
damage or a shortage, immediately notify carrier.
1.4
DISPLAY UNIT
The display unit will indicate status and will display selected
temperature. Refer to Part 8 TH Control Panel, which
provides details to modes and error codes displayed on the
appliance.
1.5
SEQUENCE OF OPERATION
1) The power switch is placed in the “ON” position.
2) Minimum 120 VAC 60Hz single phase (15A circuit) is
supplied to the Terminal Strip.
3) 24 VAC power is supplied to the TH Controller which
provides all setup and ignition control functions.
4) A heat request is detected by the DHW Sensor.
5) After the appliance water pump starts, flow is proven
by the flow proving device.
6) The TH Controller initiates a start-up sequence once it
receives a heat demand.
7) Voltage is sent to the electrically commutated DC
motor of the combustion fan after the internal safety
checks are satisfied.
8) The fan will run at Pre-Purge speed until the Pre-Purge
timer is satisfied. Once this is complete the TH
Controller provides a signal to modulate down to
ignition fan speed.
9) The TH Controller supplies voltage to the air/gas ratio
control valve. The air/gas ratio control valve senses the
pressure across the venturi and supplies gas to pre-
mix with air.
10) The igniter will continue to spark for 6 seconds, with
the gas valve opened 2 seconds after the initial spark
is generated with the fan running at ignition speed.
11) Spark igniter lights the air/gas mixture. The TH
Controller looks for a minimum flame rectification
signal of 0.8 µA DC from the flame sensor during the
Main Flame Establishing Period. If the signal is present
the TH Controller will allow the gas valve to remain
open. The burner is now firing at starting input rate.
12) The fan is kept at ignition speed until the stabilization
timer is satisfied.
13) The boiler will modulate to the correct fan speed to
meet the heat demand. The modulation rate is
controlled via Pulse Width Modulation (PWM) signals
provided by the TH Controller.
14) The fan speed will slowly decrease as the heat request
nears the heat demand. If the heat demand is
sustained for a long duration of time the boiler will get
to a point of steady-state and the fan will rotate at a
constant speed.
15) When the heat demand is satisfied or is removed the
burner will shut off and the fan speed will ramp up to
the preset Post-Purge speed until the Post-Purge
Timer is satisfied.
16) The pump continues to circulate until the post-pump
time is satisfied.
17) The boiler will then go into Standby as it waits for the
next heat demand.
Figure 1: TH Ignition Cycle
