A.O. Smith ST-300, User And Service Manual

Page: 33 / 52

ST 300
Installation, Service and User Manual
33
4 Maintenance
4.1 Preparation for
maintenance
4.2 Water-side
maintenance
4.2.1
Warning
Maintenance may only be carried out by a competent person.
At each service, the storage tank undergoes maintenance on water side. The
maintenance must be carried out in the following order.
1. Preparation for maintenance
2. Water-side maintenance
3. Finalising maintenance
Note
Before ordering spare parts, it is important to write down the installation type, storage
tank model and the full serial number of the storage tank. These details can be found
on the rating plate. Only by ordering with this information can you be sure receive the
correct spare parts.
The preparation for maintenance consists of testing and checking if all components
are still working properly by completing the following steps:
1. Test the operation of the overflow valve of the protected cold supply setup. The
water should discharge out.
2. Check the drainage pipes from the discharge points of all valves and remove any
scale deposits that may be present.
3. Drain the storage tank.
Water-side maintenance consists of descaling and cleaning the tank and checking
the anodes.
Descaling and cleaning the tank
Scale and lime build-up prevent effective conduction of the heat to the water.
Periodic cleaning and descaling prevents build-up of these deposits. This increases
the service life of the storage tank, and also improves the heating process.
Take the rate of scale formation into account when deciding on the service interval.
Scale formation depends on the local water composition, the water consumption and
the water temperature setting. A water temperature setting of maximum 60°C is
recommended for the prevention of excessive scale build-up.
To guarantee a good, watertight seal around the cleaning opening, replace the
gasket, washers, bolts and, if necessary, the lid with new parts before reassembly.
Spare parts are obtainable from the supplier/manufacturer.
To simplify descaling and cleaning of the tank, the storage tank is equipped with a
cleaning opening.