Technical data

9.2.6 Burner / spark ignition probe

Remove the front cover of the heat exchanger as described in § 9.1.2.

Unscrew the 4 screws shown on the photo to allow the stainless steel

burner mesh to be removed. These screws are Torx 20 (RVS A2 4,2x25”) or

Allen bolt M4x20 (units before 2006). The burner gasket should be checked

and replaced if damaged. Replace the burner mesh assembly and refit the

screws.

The spark ignition probe is shown in the photo in §9.1.2 and also the

diagram in §8.3. To replace the probe, pull off the ignition cable and

unscrew the 2 screws (Allen bolt M4x8). The seal should be checked and

replaced if damaged. Replace the probe and refit the seal and the screws.

Check the spark gap and replace the front cover, as described in §9.1.2.

9.2.7 Flow / return temperature sensors

The supply temperature sensor is located above the return temperature

sensor. The latter is shown in the photo. Disconnect the two pin connector

and release the spring clip. Pull out the sensor and replace.

9.2.8 Pressure relief valve

Remove the plastic pipe from the safety discharge. Undo the pressure

sensor capillary and undo the union at the connection with the CH flow pipe.

Remove the pressure relief valve and inlet pipe. Remove the plastic fitting

from the discharge and undo the pipe connection to allow removal of the

valve. Fit replacement valve in reverse order using a sealant suitable for

potable water.

9.2.9 Pressure gauge sensor

Undo the pressure sensor capillary and unscrew the two posidrive screws to

release the cable clamp. Remove the gauge and capillary, and replace.

9.2.10 Pump head

Disconnect the pump wires from the controller (see note in §9.2.1). Undo

two Allen bolts on the Wilo pump head to remove the pump head from the

body. Fit replacement pump head in reverse order. The pump must be

vented via its vent plug after refilling the appliance.

9.2.11 Expansion vessel (HE26 only)

Unscrew the flexible hose connection, making sure that the sealing ring is

not damaged. Unclip the bracket holding the vessel and fit replacement

including the sealing ring. Using the Schroeder valve on the expansion

vessel, and pump if required, check the pressure is 1 bar.

Note: The replacement of the components

below this box

requires the appliance to be drained:-

CH side – Drain the appliance using the drain tap and drain the

system at the lowest point.

After replacement, refill the appliance as given in § 6.1.