Maintenance and service
5.3Mineral scale build-up
Periodic descaling may be necessary in areas with high mineral content in the water. Scale buildup in the heat exchanger may result in lower flow rates, error codes of A7 and E9 and boiling sounds in the heat exchanger.
Descaling using a pump
1.Disconnect electrical supply from the water heater.
2.Shut off the water supply to the water heater using (installer supplied)
3.Open hot water taps to drain and relieve pressure from the plumbing system.
4.Drain water from the unit's heat exchanger by disconnecting inlet and outlet water connections from the heater.
5.Connect a line (A) from the outlet of the circulating pump (installer supplied) to the inlet water fitting on the water heater.
6.Connect another line (B) to the water outlet fitting on the water heater. Route the other end of this line into a descaling reservoir.
7.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.
8.Make sure all connections are "hand tight.".
9.Fill reservoir with descaling solution so both lines inside are submersed. We recommend straight white vinegar. If using a commercial descalant, refer to manufacturer's instructions on dilution with water.
10.Operate the circulating pump.
11.Make sure there are no leaks and the solution is flowing from the descaling reservoir through the heater and returning to the reservoir.
12.Run 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).
13.Disconnect all lines and drain all solution from heat exchanger. Properly discard of solution.
14.Position a container below the hot water outlet and reconnect cold water supply. Open cold water supply
15.Shut cold water
16.Reconnect electrical supply to unit, open water isolation valves, and return the unit to service.
Fig. 39
5.4Adjusting CO2
The CO2 can only be adjusted by a certified gas technician with a calibrated CO2 analyzer.
Caution: One factor that may affect CO2 levels is improper gas pressure. Please see Chapter 3.8 for the procedure to measure gas pressure and record your findings below:
Static Gas Pressure: |
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P1 Operating Pressure: |
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The P1 minimum operating gas pressure is 5" WC for Natural Gas and 11"WC for Propane. Do not proceed in adjusting CO2 until pressure is at or above these levels, but not to exceed 14” WC.
A. Once Gas Pressure is adequate
BTurn ON/OFF switch to the OFF (O) position.
BRemove brass flat head screw on the exhaust collar as seen in Fig. 40.
BInsert CO2 analyzer probe into the measuring port. The tip of the probe should be in the center of the flue
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