Table Of Contents - Bosch 520-HN -L Manual

2 | Index
Index
1 Key to symbols and safety instructions . . . . . . . . . . . . 3
1.1 Key to symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 General safety instructions . . . . . . . . . . . . . . . . . . . 3
2 Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Appliance details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 520 HN specifications (Technical data) . . . . . . . . 7
3.2 Unpacking the 520 HN heater . . . . . . . . . . . . . . . . 8
3.3 General rules to follow for safe operation . . . . . . . 8
3.4 Dimensions and installation clearances . . . . . . . . 10
4 Installation instructions . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2 Proper location for installing your heater . . . . . . 11
4.3 Mounting Heater . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.4 Combustion air requirements . . . . . . . . . . . . . . . . 13
4.5 Venting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.5.1Horizontal venting . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5.2Vertical venting . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.6 Gas piping & connections . . . . . . . . . . . . . . . . . . . 16
4.7 Measuring gas pressure . . . . . . . . . . . . . . . . . . . . 20
4.8 Water connections. . . . . . . . . . . . . . . . . . . . . . . . 20
4.9 Recirculation application . . . . . . . . . . . . . . . . . . . 21
5 Operation instructions . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.1 For your safety read before operating
your water heater . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.2 Lighting instructions . . . . . . . . . . . . . . . . . . . . . . . 21
5.3 To turn off appliance . . . . . . . . . . . . . . . . . . . . . . . 22
5.4 Adjusting the water temperature . . . . . . . . . . . . . 22
5.5 Power adjustment knob . . . . . . . . . . . . . . . . . . . . 23
5.6 Draining the appliance . . . . . . . . . . . . . . . . . . . . . 23
6 Maintenance and service . . . . . . . . . . . . . . . . . . . . . . . 24
6.1 Maintenance intervals . . . . . . . . . . . . . . . . . . . . . . 24
6.2 Water valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6.3 Pilot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.4 Main burners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.5 Vent assembly / heat exchanger . . . . . . . . . . . . . . 25
6.6 Mineral scale build-up . . . . . . . . . . . . . . . . . . . . . . 25
6.6.1Descaling heat exchanger . . . . . . . . . . . . . . . . . . . 25
6 720 644 942 (2014/11)
7 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7.2 No spark at pilot with water flow . . . . . . . . . . . . . 26
7.3 Spark appears when hot water is turned on,
but pilot and burners will not ignite . . . . . . . . . . . 26
7.4 Pilot lights, but burners will not come on . . . . . . 27
7.5 Main burners go out during hot water use . . . . . . 28
7.6 Hot water temperature fluctuates at tap . . . . . . . 28
7.7 Water is too hot . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
7.8 Water is not hot enough . . . . . . . . . . . . . . . . . . . . 29
7.9 Burners ignite without hot water flow . . . . . . . . . 29
7.10 Low hot water pressure . . . . . . . . . . . . . . . . . . . . 29
7.11 Noise when heater is running . . . . . . . . . . . . . . . . 30
7.12 Burners do not operate cleanly; yellow flames
when operating . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8 Protecting the environment . . . . . . . . . . . . . . . . . . . . 30
9 Interior components and diagram parts list . . . . . . . 31
9.1 Interior components . . . . . . . . . . . . . . . . . . . . . . . 31
9.2 Components diagram . . . . . . . . . . . . . . . . . . . . . . 32
9.3 Parts list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
10 LIFETIME LIMITED WARRANTY FOR BOSCH TANKLESS
WATER HEATERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
11 Installer Checklist to be completed by installer upon
installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
520 HN