John Wood Commercial - AJWS - Manual (Page 23)

THERMOSTAT TROUBLESHOOTING FLOWCHART
23
0 1 2 3 4 5 6 7 8 9
0°C 32648 31026 29495 28049 26682 25389 24166 23010 21915 20879
10°C 19898 18968 18088 17253 16461 15710 14998 14322 13680 13071
20°C 12492 11942 11419 10922 10450 10000 9572 9165 8778 8409
30°C 8057 7722 7403 7099 6808 8532 6268 6016 5775 5546
40°C 5327 5117 4917 4726 4543 4368 4201 4042 3889 3742
50°C 3602 3468 3340 3217 3099 2986 2878 2774 2675 2579
60°C 2488 2400 2316 2235 2157 2083 2011 1942 1876 1813
70°C 1752 1693 1637 1582 1530 1480 1432 1385 1340 1297
80°C 1256 1216 1177 1140 1105 1070 1037 1005 974 944
90°C 916 888 861 835 810 786 763 741 719 698
40°F 26109 25400 24712 24045 23399 22771 22163 21573 21000 20445
50°F 19906 19383 18876 18383 17905 17440 16990 16553 16128 15715
70°F 11884 11592 11308 11032 10763 10502 10248 10000 9760 9526
90°F 7333 7165 7000 6839 6683 6531 6383 6238 6098 5961
100°F 5827 5697 5570 5446 5326 5208 5094 4982 4873 4767
120°F 3758 3679 3602 3527 3453 3382 3312 3244 3177 3112
140°F 2488 2439 2391 2344 2298 2253 2209 2166 2124 2083
160°F 1688 1656 1625 1595 1566 1537 1509 1481 1454 1427
180°F 1170 1150 1129 1110 1090 1071 1053 1035 1017 999
190°F 982 965 949 933 917 901 886 871 857 842
200°F 828 814 801 788 775 762 749 737 725 713
Resistance (K ohm s)
Tem perature
Sensor Resistance vs. Tem perature
Table 4
Replace
set pot.
Replace
thermostat
circuit board.
Replace
bad
sensor(s).
Check
damper.
Take ohm reading
from upper and
lower sensors
and compare with
chart in Table 4.
(A temp. reading
from a water
sample taken
from T&P valve is
also needed for
this test).
Check orange
wire from ECO
board to
damper for 24V.
Check purple
wire from ther-
mostat for 24V.
Will ECO board
reset?
High water
temp.
Check ECO
and ICM.
Is ECO light
“ON”?
Replace ECO
board.
Slowly turn set
pot from low to
high. Reading
should change
smoothly with
no skips, jumps
or glitches.
With an ohmmeter
set at X1, check
orange wires on
set pot. (3,000
ohms at lowest
setting & 0 ohms
at highest setting.)
No voltage or
low voltage
from purple
wire between
thermostat
board & ECO
board.
OHMs
reading no good
OHMs show OK
Yes
No
No
No
No No
Yes Yes
Yes
OK Has bad spots