Potterton Performa 24 Installation & Servicing Instructions Manual page 34

Plate Heat Exchanger
Rubber Seal
Sensing Pipes
Microswitch
Bracket
Fig. 82
Diaphragm
Spring
34
Fig. 81
Manifold
Grub Screws
DHW Pressure
Differential Valve
Diaphragm
Plastic Disc
Pushrod
Fig. 83
12.0 Changing Components
12.20 Plate Heat Exchanger (Fig. 81)
1. Drain the primary circuit.
2. While supporting the heat exchanger undo the
screws securing it to the brass manifolds.
3. Withdraw the heat exchanger upwards and to
the left of the gas valve, taking care not to
damage any wires or controls.
Seals
4. There are four rubber seals between the
manifolds and heat exchanger which may need
replacement.
5. Ease the seals out of the manifold. Replace
carefully, ensuring that when the seal is inserted
into the manifold it is parallel and pushed fully in.
6. When fitting the new heat exchanger note that
the left hand location stud is offset towards the
centre more than the right hand one.
7. Reassemble in reverse order.
12.21 Diverter Valve Assembly (Fig. 82)
The diverter valve assembly comprises of a
central heating pressure differential valve and a
domestic hot water pressure differential valve.
These are connected to a manifold which is
joined to the plate heat exchanger.
DHW Pressure Differential Valve (Fig. 83)
1. Drain the primary circuit.
2. Undo the screw securing the microswitch
bracket to the valve (Fig. 82).
3. Disconnect the two sensing pipes and slacken
the grub screws securing the valve to the diverter
manifold.
4. Draw the valve away from the diverter
manifold. The valve may now be replaced or split
to examine the diaphragm.
5. To examine the diaphragm hold the valve body
securely and carefully remove the six screws.
The diaphragm spring will force apart the two
halves of the valve.
6. Remove the plastic disc and pushrod
assembly. Carefully examine the diaphragm and
replace it if there is any damage.
7. Reassemble in reverse order.