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”.
17
Sequence of Operation Component Diagram
1)
Hot Water Tap
2)
Water Flow Servo Motor
3)
Water Flow Sensor
4)
Inlet Water Temperature Thermistor
5)
Combustion Chamber Thermistor
6)
Outlet Water Temperature Thermistor
7)
PCB
8)
Water Filter (Strainer)
9)
Gas Inlet Solenoid Valve
10)
Gas Solenoid Valve 1
11)
Gas Solenoid Valve 2
12)
Proportional Gas Flow Regulator
13)
Nozzle
14)
Burner
15)
Igniter
16)
Igniter Electrode
17)
Flame Sensor
18)
Heat Exchanger
19)
Over Temperature Limiter
20)
Exhaust (Flue) Outlet
21)
Combustion Chamber
22)
Anti Frost Heater
23)
Fan
24)
Fan Motor
25)
Drain Plug With Relief Valve.
26)
Controller (Optional)
Bypass Operation
The bypass is a section of copper pipe work connected between the water body assembly
and the outlet of the heat exchanger and allows a quantity of cold water to bypass the heat
exchanger. The purpose of the bypass is to ensure the heat exchanger operates at
temperatures above the dew point of the combustion gases, ensuring condensate is not
produced, but low enough to maximise the heat exchangers life. The PCB activates the
water bypass control motor based on heat exchanger temperature and selected outlet water
temperature.
Anti-Frost Heater Circuit
All models have an anti-frost heater circuit. The anti-frost heaters are wired in series and
operate independently from the water heater.
A thermostat sensing ambient air temperature, positioned in the wiring loom near the bottom
of the water heater, activates the anti-frost heaters when the ambient air temperature falls
to 4ºC (+4ºC/-2ºC) and deactivates the anti-frost heaters when the temperature rises above
12ºC.
In the event a heater block becomes open circuit the total heater circuit is rendered
inoperable. There are six anti-frost heaters in total.
Refer to ‘Anti-Frost Heaters’ on page 74 for replacement procedure.
