TR
OUBLE
SHOO
TING
TR
OUBLE
SHOO
TING
On-Demand Water Heater Service Handbook for 240, 340 & 540 Condensing Models • 23
TR
OUBLE
SHOO
TING
TR
OUBLE
SHOO
TING
DIP SWITCH SETTINGS
The computer board layout for all 240 and 340 models is identical. See “Wiring
Diagrams,” page 30. The DIP switches have certain special functions as shown
on the following table and generally should not need adjustment.
Verify the functions of each DIP switch carefully before changing any settings.
If you have questions, contact the technical service department.
Table 5: 240 (T-H3J) / 340 (T-H3S) models
NOTE: Dark squares represents DIP switches
Bank of DIP Switches
Figure
9
: 240 (T-H3J) and 340 (T-H3S)
NO.
FUNCTIONS
ON POSITION
1
Gas type
Propane
Disable
2
Natural gas
Disable
3
4
5
FM+, FM- and Input-
(Fan motor speed is increased automa
ti
cally.)
6
7
Installa
tion
se
ttings
8
N/
A (Do not change switch position.)
N/A
N/A (Def
ault)
9
Output temperatur
e settings
(Default 120°F / 49°C)
140 °F (60
°C)
120 °F (49
°C)
(Def
ault)
10*
Deacti
va
tion
of the exhaust temperature control
Enable
Disable
(Def
ault)
DEFAULT
No.
3: OFF
No
.
4: OFF
No.
5: OFF
OFF
ON 1 2 3 4 5 6 7 8 9 10
Propane
OFF
ON
1 2 3 4 5 6 7 8 9 10
Natural
Gas
OFF
ON
1 2 3 4 5 6 7 8 9 10
Outdoor models
No. 6
: OFF
No.
7 : ON
OFF
ON 1 2 3 4 5 6 7 8 9 10
Set DIP switches shown
in the table below
.
OFF POSITION
WARNING:
Do not adjust DIP switch No. 10 without guidance from the technical service department. The only time
DIP switch 10 should be set to ON is when your unit is being hooked up to CAT III/IV metal vent with a maximum temp.
rating of 480° F. The No. 10 DIP switch deactivates the exhaust temperature control when set to the ON position.
Failure to follow this warning can lead to personal injury, carbon monoxide poisoning, or death.
*
Vent se
ttings
(Indoor models only)
3" ven
ting
s
5 to 20
ft
(DEFAULT)
21 to 40
ft
41 to 70
ft
4" ven
ting
s
5 to 50
ft
(DEFAULT)
51 to 100
ft
N/A
No.
6 : ON
No.
7 : OFF
No.
6 : OFF
No.
7 : OFF
No.
6 : ON
No.
7 : ON
Set DIP switches shown in the table below depending on the vent leng
th.
OFF
ON 1 2 3 4 5 6 7 8 9 10
OFF
ON 1 2 3 4 5 6 7 8 9 10
OFF
ON 1 2 3 4 5 6 7 8 9 10
For correct settings, see pages 26 and 27.
