Diverter Valve Assembly; Plate Heat Exchanger - Baxi Combi 105 HE Installation & Servicing Instructions Manual

Plate Heat Exchanger

Rubber Seal
Fig. 81
Sensing Pipes
Microswitch
Bracket
Fig. 82
Diaphragm
Spring
Fig. 83
44
© Baxi Heating UK Ltd 2007
Diverter Manifold
Grub Screws
DHW Pressure
Differential Valve
Diaphragm
Plastic Disc
Pushrod
14.0 Changing Components
14.21 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 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.
14.22

Diverter Valve Assembly

(Figs. 82 & 83)
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.