Baxi Combi Instant 80e Installation & Servicing Instructions Manual page 37

Plate Heat Exchanger
Rubber Seal
Offset Stud
Rubber Seal
Fig. 64
Spring Clip
Microswitch
Fig. 65
Diaphragm
Spring
DHW Pressure
Differential Valve
Cover
DHW Pressure
Differential Valve
Sensing Pipe
Diaphragm
Thrust Plate
Pushrod
Fig. 66
12.0 Changing Components
12.21 Plate Heat Exchanger (Fig. 64)
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 require
replacement.
5. Ease the seals out of the manifolds. Replace
carefully, ensuring that the seal is inserted into
the manifold 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.
12.22 Diverter Valve Assembly
(Figs. 65 & 66)
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 Diaphragm
(Figs. 65 & 66)
1. Turn off the mains water inlet tap and drain the
domestic hot water by turning on a hot tap.
2. Prise off the spring clip retaining the
microswitch. Pull the switch away.
3. Undo the sensing pipe nut from the valve and
slacken the nut at the inlet manifold. Ease the
pipe away from the valve.
4. Undo the screws securing the differential valve
cover.
5. Carefully draw off the cover and remove the
diaphragm, noting the orientation.
6. Fit the new diaphragm and reassemble in
reverse order.
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