TM049 27L Continuous Flow Service Instructions
REV AL
– Issued April 2019
This document is stored and maintained electronically by Rheem Technical Support.
All printed copies are deemed “uncontrolled”.
16
SEQUENCE OF OPERATION
Refer to ‘Sequence of Operation Component Diagram’ on page 17 to view components
shown in brackets e.g.
(1)
1. When a hot water tap
(1)
is opened, cold water (or preheated water if a solar pre-heater
is installed) enters the water heater and passes through the Water Flow Sensor
(3)
and
Heat Exchanger
(18)
. Note: The inlet water temperature must be less than or equal to
58ºC and less than or equal to the set point temperature minus 2ºC for operation to occur
past this point; otherwise water will pass straight through the heat exchanger and fan and
burner operation will not occur (for more information on this subject refer to the section
titled
‘In-series Gas Boosting’ on page 19).
2. The Water Flow Sensor
(3)
sends a pulse signal to the PCB
(7)
. Once the pulse signal
reaches a pre designated frequency (at a min. flow rate of 2L/m the PCB
(7)
activates
the Fan Motor
(24)
and the Fan
(23)
starts rotating.
3. After the Fan
(23)
completes a pre purge to ensure the vent is clear, the Proportional
Gas Flow Regulator
(12)
allows gas to flow to the Burner
(14)
.
At the same time the
Igniter
(15)
starts sparking continuously and ignites the gas at the Burner
(14)
.
4. After ignition the Flame Rods
(17)
sense and monitor the burner flame. The PCB
(7)
constantly monitors all inputs to ensure the outlet water temperature is maintained within
1
o
C of the thermostat setting. The Proportional Gas Flow Regulator
(12)
continuously
adjusts the gas volume and the water flow is also adjusted to assist in supplying a stable
hot water temperature at all times.
5. As the gas flow rate, controlled by the Proportional Gas Flow Regulating Valve
(12)
changes, the PCB
(7)
varies the speed of the Fan Motor
(24)
to maintain the correct air
gas mix ratio.
6. When the hot tap
(1)
is closed, the pulse signal from the Water Flow Sensor
(3)
stops
and the burner flame is extinguished by closing the gas valve. The post purge operation
then commences to cool the heat exchanger
(18)
.
7. Once the post-purge operation is completed power to the Fan Motor
(24)
is cut and the
Fan
(23)
stops.
