TM081 Rheem 834 Series Hydroelectric CFGWH Service Instructions
REV: AA Issued: 22/02/17
This document is stored and maintained electronically by Rheem Technical Support. All printed copies are deemed uncontrolled.
14
Operational Flow Chart
– All Models
START
Flow sensor detects
water flow and pulses
voltage from TC to TC
Hot tap open?
YES
MASV driven to
minimum gas position
YES
(1) Hot water outlet
temp sensor
< 20°C (cold start)
YES
NO
Energise P700 ignition
module
Igniter pulse ignition
(spark) on
Flame detected
(> 0.5 µA) within
45 seconds?
Igniter pulse ignition
(spark) off
YES
Fault detected?
(3) MASV adjusted
(Gas flow rate control)
NO
YES
SV1 energised
SV2 & SV3 energised
after 4 seconds
Igniter pulse ignition
(spark) off
NO
(Critical fault)
Water flow rate
> 2.7 L/m?
TC determines shut
down due to low water
flow (or hot taps closed)
NO
SV2 & SV3
de-energised
De-energise P700
ignition module
Battery recharge
off (if on)
Water valve de-
energised (if on)
Battery voltage
> 3.1 VDC?
MASV driven to
minimum gas position
YES
Hot water outlet temp
sensor detects
≥ 85°C
Red LED 7 flash
(2) Main burner circuit
abnormal
Red LED 6 flash
Hot water outlet temp
sensor abnormal
Red LED 5 flash
False flame, ignition
failure or loss of flame
Red LED 4 flash
False flame
detected
≥ 3 sec?
NO
YES
(Critical fault)
SV3 / MASV faulty
Red LED 3 flash
P700 ignition circuit
abnormal
Red LED 2 flash
Overheat switch
open circuit
Red LED 1 flash
Was a critical fault
detected?
NO
NO
YES
NO
YES
Hot taps closed?
NO
Flow sensor detects no
water flow and ceases
pulse generation
LED indication removed
YES
Note: water throttle valve
is de-energised when hot
water outlet temp sensor
detects ≥ 20°C or 12.5
seconds has expired
Is fault loss of
flame?
A
YES
A
SV2 & SV3
de-energised
Pilot
valve
Main
burner
valves
Igniter pulse ignition
(spark) on
Flame detected
(> 0.5 µA) within
45 seconds?
NO
(Critical fault)
Igniter pulse ignition
(spark) off
SV2 & SV3 energised
after 4 seconds
YES
Battery recharge
function on until battery
voltage is 3.5 VDC
NO
Hydro electric generator
generates voltage
Hydro electric generator
ceases to generate
voltage
Hydro electric generator
ceases to generate
voltage
Energise water throttle
valve to reduce water
flow by 33 ~ 50%
Notes:
(1) Re cold start: Provided setpoint temperature is 60°C, battery voltage is >
3.1 VDC and water flow rate through the heater is > 6 L/m.
(2) Re: Red LED 6 flash fault. This fault will occur if a 15°C temp rise is not
detected by the hot water outlet temp sensor within 45 ~ 180 seconds from
main gas valve (SV2 & SV3) energisation (actual time is flow rate dependent).
(3) MASV is continually adjusted according to hot water outlet temp (as
detected by the hot water outlet temp sensor)
and the heater’s setpoint
temperature i.e. lower hot water temp = more gas. Note: If water flow rate
through heater is reduced by ≥ 1.4L/m, the pilot will light (SV1 energised), the
main burner will extinguish (SV2 & SV3 de-energised), the MASV will readjust
and the main burner will relight and pilot extinguish after a two second delay.
(4) Non critical faults: Battery disconnected or battery voltage
≤ 3.1 VDC
(green LED will continuously flash) or water throttle valve malfunction (red
LED will continuously flash, green LED will extinguish).
TC = Temperature Controller
TC initialised.
Green LED on
Battery voltage
> 2.8 and < 3.5 VDC?
YES
This is not
a fault
SV1 de- energised
MASV driven to
minimum gas position
SV1 energised
second loss of
flame fault within 1
water flow cycle?
NO
YES
(Critical fault)
SV1 de-energised
Note: Pilot operates
on residual gas for
approx 6 seconds
TC green LED will
extinguish whilst
charging is in
progress
SV1 de- energised
Note: Pilot operates
on residual gas for
approx 6 seconds
Pilot
valve
Main
burner
valves
(4) Is fault a non
critical fault?
NO
YES
NO
(Critical fault)
Water flow rate
(flow sensor pulse)
> 3 L/m?
NO
