Installation / Operation Instruction Manual

42
Maintenance and service
RTG-K-199/160N/X2 – 6 720 813 642 (2022/06)
NOTICE:
Use of agents such as anti-freeze is not permitted and voids the
warranty, as they may cause damage to the water heater's
internal components.
1. Press ON/OFF switch on the water heater to turn OFF the
heater and unplug power supply cord. The display should
be blank.
2. Shut off gas supply to heater.
3. Shut off the water supply to the water heater using installer
supplied shutoff valve.
4. Open hot water faucets to drain and relieve pressure from
the plumbing system. If water continues to flow after 5
minutes, a crossover of the hot and cold water pipes is
present and must be corrected before proceeding.
5. Disconnect the inlet and outlet water pipes from the water
heater. Place a small bucket underneath the water heater to
catch residual water remaining inside the water heater.
6. Using an air compressor, blow short bursts of air (25psi
max) through the inlet water connection until there is no
water present coming through the outlet water connection
of the heater.
7. Empty condensate trap.
8. Reconnect water fittings, refill the condensate trap and
return heater to service when danger of freezing has
passed.
7.3 Mineral scale build-up
Periodic descaling may be necessary in areas with high mineral
content in the water, (see table 11, Water Quality). Scale
buildup in the heat exchanger may result in lower flow rates,
error codes of AA, E3, E5 and boiling sounds in the heat
exchanger.
A water softener is required if the water hardness exceeds 12
grains/gal (200 mg/l) calcium carbonate. Damage to the water
heater resulting from hard water/scale deposits will not be
covered under warranty.
Descaling using a pump
▶ Disconnect the electrical supply from the water heater.
▶ Shut off the water supply to the water heater using (installer
supplied) shutoff valve.
▶ Open hot water faucets to drain and relieve pressure from
the plumbing system.
▶ Drain water from the unit's heat exchanger by
disconnecting inlet and outlet water connections from the
heater.
▶ Connect a line (A) from the outlet of the circulating pump
(installer supplied) to the inlet water fitting on the water
heater (see fig. 43).
▶ Using another line (B), connect the water outlet fitting on
the water heater. Route the other end of this line into a
descaling reservoir.
▶ Using a 3rd line (C) from the descaling reservoir, connect to
the inlet side of circulating pump. Install a filter on the end
of the line in the descaling reservoir.
▶ Make sure all connections are "water tight".
▶ Fill bucket with descaling solution so both lines inside are
submersed. We recommend a straight white vinegar
solution. If using a commercial descalant, refer to
manufacturer's instructions for proper dilution ratio.
▶Operate the circulating pump.
▶ Make sure there are no leaks and the solution is flowing
from the descaling reservoir through the heater and
returning to the reservoir.
▶ Run the solution through the heater until the solution
returning to the descaling reservoir comes out clear.
(Changing to a fresh solution may be necessary during this
process).
▶ Disconnect all lines and drain all solution from heat
exchanger. Properly discard the solution.
▶ Close the inlet drain connection.
▶ Position a container below the hot water outlet and connect
the cold water supply. Open the cold water supply shutoff
valve and flush the heat exchanger with clean water.
▶ Close the cold water shutoff valve and reconnect hot water
supply to the water heater.
▶ Close the outlet drain connection.