32
WARNING: Water that is left standing in a stainless steel water cylinder for long periods without draw off will
become de-oxygenated and potentially corrode the vessel material. If the installation is to be left unused
following installation and commissioning the water cylinder should be drained or regularly (once per week)
flushed through with fresh mains water.
When placing the unit into service the procedure for filling the unit and the system checks detailed below should be
repeated.
- DO NOT switch on any heat source connected to the water heater until the unit has been filled with water and
checked for leaks.
- Check that all installation, electrical and safety requirements have been met.
- Check that all water and electrical connections are correctly made and are tight.
- Open a hot tap supplied by the unit, turn on the cold water supply to the unit.
- Allow the unit to fill and leave the hot tap running for a short while to purge any air and flush out the pipework. Close
the hot tap.
- Open successive hot taps to purge any air from the system.
- With all hot taps closed, check the system for water leaks and rectify as necessary.
- Manually test the operation of the Pressure Relief Valve. Ensure water flows freely from the valve and through the
discharge pipe.
- Fill the auxiliary boiler primary circuit following the boiler manufacturers commissioning instructions. If motorised
valves are used to control the primary flow ensure these are set to the manual open position for commissioning.
When the primary circuit is full return the motorised valves to the AUTO position. Vent any trapped air by opening
the air bleed point or automatic air vent.
- For heating by auxiliary heat exchanger switch on the electrical supply to the boiler and ensure the programmer is
set to HOT WATER mode. Check that any motorised valves or primary pumps are working and allow the unit to
heat.
- Fill the solar thermal primary circuit following the manufacturers’ instructions.
Descaling the unit
- Little maintenance is required, however in hard water areas the unit will require periodic descaling to ensure efficient
operation. To descale the unit:
- Switch off and disconnect the electrical supply and shut down any heat sources. Turn off the water supply to the unit.
- Open a hot tap served by the unit to relieve any system pressure. Empty the unit by opening the drain valve in the
inlet pipework.
- Open the lower (solar) terminal cover. Remove the solar sensor from the pocket.
- Unscrew brass backnut. A key spanner is provided with the unit for easy removal/tightening of the backnut. Remove
the thermostat pocket plate from the unit. NOTE over time the gasket may become stuck to the mating surface, to
break the seal insert a round bladed screwdriver into the pocket on the mounting plate and gently lever up and
down.
- The loose scale in the base of the unit can be removed by inserting the suction hose on a “wet and dry” vacuum
cleaner and sucking the scale out of the unit.
- Replace sensor pocket plate. Secure in place by re-fitting the backnut and tightening. It may be helpful to support
the sensor pocket plate using a round bladed screwdriver inserted into the pocket whilst the backnut is being
tightened.
- Replace the solar controller sensor into the pocket . Ensure they are fully inserted.
- DO NOT SWITCH ON ANY OF THE HEAT SOURCES UNTIL THE UNIT HAS BEEN RE-FILLED WITH WATER.
Re-commission the unit following the Installation and COMMISSIONING instructions.
COMMISSIONING
MAINTENANCE
307625_Baxi_Install Guide_AW:Dual cover follow on
1/12/10 14:43 Page 32
