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Function - Bosch US3 Installation Manual And Operating Instructions

Electric water heaters
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US
2.7

Function

How the water heater works:
• Water comes in through the cold water inlet.
The heater is designed for cold water supply
only. Do not supply with pre-heated water.
• The flow switch senses how much water is passing
through the unit. If it detects more than the preset
level, the unit's heating elements switch on. This is
shown by the neon light glowing.
• The water is heated instantly as it passes through the
copper heat exchanger tube.
The temperature of the water coming out of the unit
depends on:
• The voltage of the electrical supply,
• The temperature of the incoming water supply,
• The setting of the power selector,
• The flow rate,
• The power rating of the unit.
• Depending on the region of the country, the
temperature of the water supply can vary between
Model
Volts
Amps
US9
240
40
US9
240
20
US9
208
35
US9
208
18
US6
277
22
US6
277
11
US3
120-110
27
US7
240-220
30
US7
240-220
15
Table 4
Manual reset thermal cut-out
The unit has a thermal cut-out (Fig. 1) which is mounted
on the heat exchanger tube. This will switch off the
heater elements if the water temperature goes above
194 °F.
If the cut-out trips it will need to be reset manually inside
the unit. This cut-out will only operate in exceptional
Element
High
Resistance
Setting
2x12 Ω
9,5kW
1x12 Ω
-
2x12 Ω
7,1kW
1x12 Ω
-
2x25 Ω
6,0kW
1x25 Ω
-
2x8 Ω
3,4-3,0kW
2x16 Ω
7,2-6,1kW
1x16 Ω
-
40 °F in winter to 70 °F in summer, with an average of
50 °F.
Fig. 3
A
Manual reset thermal cut out
The table below shows the rise in water temperature you
can expect from the unit:
Low Setting
Temperature Rise (deg F) at Flow Rate (GPM)
0,5
0,75
GPM
GPM
-
NA
84F
4,75kW
NA
42F
-
NA
64F
3,5kW
NA
32F
-
81F
55F
3,0kW
41F
28F
-
41F
28F
-
NA
63F
3,6- 3,05kW
NA
32F
circumstances (Fig. 3). Call your service person or Bosch
Water Heating if this happens frequently.
Information about the heater | 7
1,0
1,5
2,0
GPM
GPM
GPM
64F
42F
32F
32F
21F
16F
48F
32F
24F
24F
16F
12F
42F
27F
NA
21F
14F
NA
20F
NA
NA
48F
32F
24F
24F
16F
12F
6 720 647 005 (2011/09)
2,5
GPM
NA
NA
NA
NA
NA
NA
NA
NA
NA

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