Worcester 28i Junior Spezifikationen PDF herunterladen (Seite 20)

IMPORTANT: Turn off the gas supply and electrically isolate

the appliance before replacing any components.

NOTE: Turning the control knob fully anti-clockwise does not

isolate the appliance electrically.

After the replacement of any components always check for gas

soundness where relevant and carry out functional checks as

described in Section 13-Commissioning.

Complete gasket and O-ring packs are available for gas and

water connections on the appliance.

DHW Circuit: Turn off the mains cold water supply at the

appliance. Refer to Fig. 13. Open a hot tap below the level of the

Component Access

Refer to Section 15, Inspection and Servicing for access to

components.

Draining the Appliance

Primary System: Turn off the heating flow and return valves at

the appliance. Refer to Fig. 13.

Open the drain tap. Fit a tube to the drain tap. Refer to Fig. 45.

Close the drain tap when the flow from the appliance has

stopped.

appliance to drain the domestic hot water from the appliance.

Important: A small quantity of water will remain in some

components even after the appliance has been drained.

Protect any electrical components when removing items from

the water circuits.

NOTE: After re-opening the mains cold water inlet valve, draw

off a little water from a tap to ensure that there is water in the

heat exchanger.

Component Replacement

Refer to Fig. 41 and 46 for an indication of the location of the

various components.

Replace any components removed from the appliance in the

reverse order using new gaskets/O-rings/sealant/heat transfer

paste where necessary. Always check that any electrical

connections are correctly made and that all screws are tight.

Remove casing and cover panels and lower the facia onto lower

lugs, as necessary, to gain access to the components. Refer to

Section 15, Inspection and Servicing.

1 Gas Valve

Remove the burner assembly as described in Section 15.4.

Carefully pull-off the electrical connections to the valve.

Remove the injector and copper washer.

Remove the two screws securing the manifold at the rear of the

combustion chamber.

Unscrew the union connection beneath the valve and ease the

valve and injector manifold from the boiler.

Use new gaskets when replacing the valve.

Do not forget to replace the burner injector and copper

washer.

Set the Gas Valve:

Connect a pressure gauge to the burner and inlet pressure test

points on the valve. Refer to Fig. 35.

Switch on the gas and electricity supplies.

Check for gas tightness at the gas valve inlet.

Refer to Section 13-Commissioning, for the method of checking

the pressures.

Check for gas soundness at the gas valve outlet.

Adjust the maximum and start pressure [minimum], as necessary,

to obtain the required pressures.

Switch off the appliance and disconnect the pressure gauge and

tighten the screw.

Check for gas soundness at the test point.

To set the burner pressure. Refer to Fig. 35.

The minimum and maximum burner pressures must be set after

a new gas control has been fitted.

Only slight adjustment is required to change pressure.

Follow the procedure described in Section 13 - Commissioning.

The maximum burner pressure must be set first, as any

adjustment of the maximum pressure influences the minimum

pressure setting.

Start the appliance in the domestic hot water mode as described

in Section 13.8. - Appliance Operation.

Turn the gas valve mode switch to maximum. Refer to Fig. 36.

Adjust the maximum pressure adjustment screw on the gas

valve to give a burner pressure of 13.6 mbar (24i), 14.7mbar (28i)

for natural gas.

For propane, the maximum pressure adjustment screw should

be adjusted to give a pressure of 35.3mbar (28i).

Turn the gas valve mode switch to minimum.

Adjust the start pressure adjustment screw on the gas valve to

give a pressure of 1.4mbar (24i), 1.2mbar (28i) for natural gas or

3.4mbar (28i), 4.6mbar (24i) for propane.

Turn the gas valve mode switch back to normal.

After completing the adjustments, check the minimum and

maximum pressures and re-adjust as necessary.

16. Replacement Of Parts

Fig. 46 . Lower casing - gas and water

controls.

1. Gas valve

2. Pump

3. Pressure gauge

4. Relief valve

5. Manifold assembly

6. DHW sensor

Fig. 45 . Boiler drain point.

7. DHW flow turbine

8. Filling loop assembly

(optional extra)

9. CH sensor

10. Pump clip

1. Pump head

2. Boiler drain point

3. Flexible hose to expansion vessel

connection

4. O-ring

In Eire additional guidance on commissioning is contained in

paragraph 15 of IS 813:2001

13.1 Water Treatment: For optimum performance

after installation, this boiler and its associated central heating

system should be flushed in accordance with the guidelines given

in BS7593 – Treatment of water in domestic hot water heating

systems. Full instructions are supplied with proprietary cleansers

sold for this purpose. If an inhibitor is to be used after flushing, it

should be used in accordance with the manufacturers instructions.

Remove all system cleanser before adding any inhibitor.

Suitable flushing agents and inhibitors are available from Betz

Dearborn on 0151 4209563 or Fernox Tel: 01799 550811.

13.2 This text describes the filling and venting of the appliance and

system when the optional internal filling loop is fitted.

Any external filling loop must be WRAS approved. Refer to Fig. 8 b.

It is very important that the appliance and system are fully vented.

Pull off the clip on bottom panel. Refer to Fig. 32.

Remove the cabinet by pulling off the clip-on facia cover.

Unscrew the two fixing screws, release the sides and lift from the

top location.

Check that the electrical supply and the gas supply to the

appliance are turned off and that all the water connections

throughout the system are tight.

Open the system valves at the appliance. Refer to Fig 13.

Open all the radiator valves.

13.3 Remove the key from the bottom panel and insert into the

filling loop. Refer to Fig. 32 and 33.

Open the mains cold water inlet valve .

Turn the key clockwise to unlock the filling loop.

The system will fill.

Vent each radiator in turn. The automatic air vent will vent the

appliance.

It is very important that the appliance and system are fully

vented and that all air pockets are removed.

Remove the cap from the pump and turn the shaft about half a

turn. Replace the cap. Refer to Fig. 34.

Check that the pressure relief valve operates by turning the knob

anti-clockwise until it releases. Refer to Fig. 17. Water should be

expelled from the discharge pipe.

13.4 Set the Expansion Vessel Pressure

The charge pressure of the expansion vessel as dispatched is

0.5bar, which is equivalent to a static head of 5m. The charge

pressure must not be less than the static head at the point of

connection. A Schraeder type valve is fitted to the top of the

expansion vessel to allow the charge pressure to be increased if

necessary. Refer to Fig. 15.

The expansion vessel must be charged to 0.35bar less than the

initial system design pressure.

Note: 1bar = 10.2m of water.

13.5 Set the System Pressure

Fill the system until the pressure gauge is at 2.5bar and check for

leaks. Turn the filling key anti-clockwise to shut the filling loop.

Replace the key in the bottom panel. Release water from the

system drain point until the required system pressure is

obtained, upto a maximum of 1.5bar. Set the pointer on the

pressure gauge to record the set system pressure.

If the pressure indicated on the gauge is greater than 2.65bar when

operating at the maximum central heating temperature then an

extra expansion vessel must be fitted to the system as close as

possible to the appliance central heating return connection.

13.6 Clock/Programmer

The controls fitted to the appliance should be set up at this

stage. Refer to the instructions sent with the control.

13. Commissioning The Appliance

Fig. 32. Bottom Panel

Fig. 34. Pump venting.

Pump

Pump cap

Electrical

connections

cover

Fig. 35. Gas valve.

Maximum

2mm

Allen key

Minimum

3mm

Allen key

Clockwise to

increase

Anti-clockwise

to decrease

Slight

movement

only is

required

1. Bottom panel

2. Filling key

3. Fixing clips

Fig. 33. Filling Loop (optional)

1. Filling loop 4. CH Return

2. Filling key 5. Mains water inlet

3. Lock/unlock Fill position

1. Burner pressure test point

2. Main gas valve connections

3. Inlet pressure test point

4. Electrical connections modulator

(Blue:Blue)

5. Gas valve sealing cap

6. Fibre washer

7. Injector

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