Since recirculation through the heater is not allowed,
the following drawing is provided to outline a
recirculation application using the Protankless water
heater with an Ariston mini tank water heater. This
schematic is for illustration only and must not be used
for actual installation without appropriate engineering
and technical advice from a professional properly
licensed in locality where the installation is made.
Fig. 17 Recirculation application
Full port shutoff valve
A small electric mini tank water heater (4-6 gallon size)
must be used for this application and designed so the
pump will circulate the water through the mini-tank and
the building's hot water return loop only. A timed or
thermostatically controlled operation of the pump is
commonly done. The 520 HN must be plumbed in line
before the mini-tank water heater. Contact Bosch
Water Heating if further instruction is needed.
For your safety, read before
operating your water heater
Warning: If you do not follow these
instructions exactly, a fire or explosion
may result causing property damage,
personal injury or loss of life.
A. This appliance is equipped with electronic ignition for
lighting the pilot and main burners. When turning the
heater on, follow these instructions exactly.
B. Before operating the unit, set the On/Off button to
position. The On/Off button is located on
the front panel. Smell all around the appliance area for
gas. Be sure to smell next to the floor because some
gas is heavier than air and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS
B Close gas valve. Open windows.
B Do not try to light any appliance.
B Do not touch any electric switch; do not use any
phone in your building.
B Immediately call your gas supplier from a neighbors
phone. Follow the gas supplier's instructions.
B If you cannot reach your gas supplier, call the fire
C. Use only your hand to push in the on/off control
button. Never use tools. Follow these instructions
exactly. If control button is jammed, close the gas
supply and call a qualified service technician.
Attempted forceful repair may result in a fire or
D. Do not use this appliance if any part has been under
water. Immediately call a qualified service technician to
inspect the appliance and to replace any part of the
control system and any gas control which has been
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