Error Code 16; Error Code 31, 32, 33 & 34 - Rheem 874W27NF Service Manual

Fault Finding Test 15
Maintenance display code
2y: Ambient Air Thermistor
3y: Cold Inlet Thermistor
4y: Heat Exchanger Thermistor
5y: Hot Water Outlet Thermistor

Error Code 16

Outlet water temperature is too hot.
Error Code 16*
**Is the unit used as an
in-series gas booster?
** 276, 866, 876 series heaters are
unsuitable for use as in-series gas boosters.
NO
Is the resistance of the heat
exchanger thermistor normal?
TEST 15
YES
Is the resistance of the hot
outlet thermistor normal?
TEST 15
YES
Is the resistance of the
proportional gas valve
correct?
TEST 12
TM061 Rheem 27 Water Star Service Instructions – Issued: 11/10
REV A Issued 08/13
This document is stored and maintained electronically by
BK R BR Y G W SW1 SW2
3 4 5 6 7 8
K
7 BL
6 W
5
Y
N
4 R
O
9
BK
4 8 BK
2
BK
3 7 R 6
1 R
2 6 5
G
1 5 Y 4
P
4 3
BL
3 O 2
2 W 1
1
BR
7 Blue & 3 Black
6 White & 3 Black
5 Yellow & 3 Black
4 Red & 3 Black
*Error 16 will occur if the unit heats the
o
C above the set point – 3
water to 20
eg: 60 + 20 – 3 = 77
Is the inlet water
YES
temperature >58
NO
Replace cold water inlet
Replace heat exchanger
NO
NO Replace hot outlet thermistor.
NO
Service. All printed copies not bearing this statement in RED are deemed "uncontrolled"
Test 15
Isolate power before conducting test.
Using a multimeter set on the ohms scale,
measure the resistance at terminal P whilst
unplugged from the PCB.
Test Point
o
C
o
C.
YES
o
C?
NO
thermistor.
thermistor.
YES
Measured Value
@20ºC – 10.3 kilo-ohms
@40ºC – 4.9 kilo-ohms
The gas booster should not
operate with an inlet temperature
o
in excess of 58 C.
Is the resistance of the cold
water inlet thermistor normal?
TEST 15
YES
Replace control PCB.
Replace the gas valve assembly.
34