ELTRA ONH-2000 User Manual

 2002 by ELTRA GmbH Germany – January 2002 – Service Manual OH 900 / ON 900 / ONH 2000
2.15-1
2.15 2.15 Water flow and furnace temperature sensing board ON21:
The board ON21 is responsible for the temperature response of the tap water valve, the
high temperature alarm of the furnace and the detection of the cooling water flow.
Do not change the settings of the temperature without checking the error massages.
Too high temperatures damage the furnace.
6
5
4
3
2
1
TP11
3 22 10
O N2 1
P 1 P2 P 3
2- 1 5- 1
TP12
TP13
TP15
BA
TP8
TP7
TP6
TP5
TP4
TP14
TP3
TP9
TP10
J 2
J 1
1
TP2
TP1
J 3
+15V
+15V
+15V
A2
B1A1
B2
A4
B3
A3
B4
"HIGH" if water
temperature
sensor broken
T P10
VRef
VRef
-
+
-
+
-
+
-
+
-
+
-
+
TP7
TP5
7
3
4
5
6
8
11
19
TP9
J1
J1
F1
2AT
VRef
"HIGH" if furnace
temp.exceeds 70°C
Water
flow sensor
2-15
TP3
"HIGH" enables
tap water valve
"HIGH" if
no problems
with temperature
T P2
VRef
High=13V-15V
Low = 0V - 1V
J3
220V
4
5
~
+15V
"LOW" if no
water flow
TP12
TP11
"HIGH" means
"no problems",
furnace can
operate
normally
TP6
NTC
furnace
temp.
sensor
NTC
water
temp.
sensor
Tap
water
flow
valve
"HIGH" if furnace
temperature
sensor broken
TP14
6.1V
4. 7V
P2
P1
+
+
+15V

ELTRA ONH-2000 Specifications

General

Brand	ELTRA
Model	ONH-2000
Category	Measuring Instruments
Language	English