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21 . THE DOMESTIC HOT WATER CONTROL THERMOSTAT
Fig. 27.
(a)
Unscrew the two slotted
MS
screws located beneath the
control box and ease away the thermostat and pump delay
timer mounting bracket.
(b) Using a pair of long nose pliers pull the retaining clip from the
thermostat pocket situated in the .domestic hot water inlet
pipe on the top of the heat bank at the rear and remove the
thermostat phial.
(c)
Remove the central clamping nut and washer.
(d) Pull off the two electrical connections from the rear of the
thermostat.
(e)
Push the thermostat body back to disengage the spindle from
the mounting bracket.
(f)
Withdraw the thermostat and thread the capillary through the
slot in the rear of the electrical control box.
(g)
Fit the new thermostat and reassemble in the reverse order.
The capillary of the replacement thermostat must be uncoiled
to assist its passage through the control box opening. With the
thermostat in position the excess capillary must be recoiled,
without tight bends, and positioned so that it is beneath the
combined feed and vent pipe but not in contact with any hot
surface. Ensure that the retaining clip is replaced into the
thermostat pocket.
22.
THE OPERATING SWITCH
(a)
Disengage the rear cover of the facia panel by releasing the four
MS
screws, two at the top and two at the bottom.
(b) Remove the push-on connections from the rear of the switch
taking note of their positions.
(c)
Squeeze together the two plastic retaining Jugs and remove
the switch from the front of the facia.
(d) Snap in the replacement switch and with the aid of the wiring
diagram (Fig.
11)
reconnect the push-on connections.
23.
THECONTROLRELAY
Fig.
28.
(a)
Ease the relay from the base by pulling horizontally.
(b)
The new relay will fit in one direction only. Push the relay into the
base until fully located.
Fig. 27.
Domestic hot water
Domestic hot water
high limit thermostat
overheat thermostat
Safety valve
23
24.
THE PROGRAMMER (IF FITTED)
(a)
Remove the rear cover of the facia panel by releasing the four
MS
screws, two at the top and two at the bottom.
(b) Remove the programmer by unscrewing the four screws
securing it to the fascia, two at the top, two at the bottom.
(c)
Fit the replacement programmer and reassemble in the reverse
order. Use only the specified programmer. Do not attempt to
fit any other model or make.
25. THE SUPPRESSOR
Fig.
28.
(a)
Unscrew the two slotted
MS
screws located beneath the
control box and ease away the thermostat and pump delay
timer mounting bracket.
(b) The suppressor is located below the terminal strip and is held
by a 'P' clip secured by a screw. Loosen the screw and ease the
suppressor clear of the bracket.
(c)
Disconnect the suppressor leads from the terminal strip and
remove.
(d) Fit the replacement suppressor and reassemble in the reverse
order. Refer to the electrical wiring diagram (Fig.
12)
to ensure
the correct connections are made.
26. THE PUMP DELAY TIMER BOARD
Fig.
28.
(a)
Unscrew the two slotted
MS
screws located beneath the
control box and ease away the thermostat and pump delay
timer mounting bracket.
(b) Release the plastic catch on the end of each mounting post and
pull the printed circuit board forward approximately 3 mm at
a time to prevent the plastic catch from returning. It may be
necessary to use an electrical screwdriver to assist in releasing
the catches.
(c)
Pull the board off the mounting posts until it is free.
(d) Disconnect the electrical connections at the terminal strip.
(e)
Locate the replacement board (with the leads at the top) over
the four mounting posts and push back squarely until the
splastic catch on the end of each post clicks into place.
(f)
Reconnect the leads with the aid of the wiring diagram (Fig.
11 ).
It is important to reconnect the leads correctly.
Fig. 28.
Earth screw
Domestic hot water
control thermostat
Suppressor
Control relay
Central heating
control thermostat
Pump delay timer board
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