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Service Manual
Singular Combi Boiler - BTC 439002301 A (12.2021)
10 Flushing the Heat Exchanger
NOTICE: BOILER DAMAGE
Flushing the Heat Exchanger annually is a required
maintenance. In hard water conditions, it needs to take a
place more often.
Flushing the Heat Exchanger is a somewhat complicated procedure. Read the
following instruction carefully before attempting this procedure.
Before Flushing the Heat Exchanger, gather the following items.
A bucket that is 5 gallons or larger (The capacity of this water heater is 0.5
gallons)
Cleaning solution diluted with water (indicating it is safe for use with
stainless steel)
3 hoses
A water circulation pump
1. Disconnect electrical power to the boiler.
2. Close the shutoff valves on both the space heating return and space heating
supply lines (V3 and V4).
3. Connect one of hoses to the circulation pump outlet and the space heating
return line at the (V1) valve.
4. Connect one hose to the circulation pump inlet and place the free end in the
bucket.
5. Connect the other hose to the space heating supply line at the (V2) valve and
place the free end in the bucket.
6. Pour approximately 4 gallons of virgin, food grade, white vinegar into the
bucket.
7. Open both valve(V1 and V2) on space heating return and space heating
supply lines.
8. Operate the pump and allow the solution to circulate through the water
heater for at least 45 minutes.
9. Rinse the cleaning solution from the boiler:
a. Remove the free end of the drain hose from the bucket.
b. Connect the hose to cold water.
c. Allow water to fl ow through the boiler for at least 10 minutes.
d. Close the valve(V1) and open shutoff valve(V4).
10. Disconnect all hose.
11. Restore electrical power to the boiler.
Figure 129
Pressure relief v
Pressure
relief valve
Space heating
supply
Space heating
return
Ball valve
Union
Circulation pump
Space
heating
return
Space
heating
supply