Worcester Highflow 3.5 OF Installation And Servicing Instructions page 20

Fig. 24.
Earth Screw
Domestic Hot Water
Control Thermostat
Pump Delay
Timer Board
Relay
Central Heating
Control Thermostat
15. THE DWH TANK THERMOSTAT
(See Figs. 22 and 24.)
(a) Unscrew the two slotted M 5 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 DHW 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 threading the capillary through
the slot in the rear of the electrical control box.
(g) Fit the new thermostat and re-assemble 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 the the
retaining clip is replaced into the thermostat pocket.
16. THE RELAY
(See Fig. 24.)
(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.
17. THE 3-POSITION SWITCH
(See Fig. 25.)
(a) Disengage the rear cover of the facia panel by releasing the
four M5 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 lugs 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.
20
Fig. 25.
Fig. 26.
/
-;:. , / '
~ORCESTER
11141\.\11-W\
HOT
Off
1
1 - -
TWICE
.,.Ill·
JU -M
WATER
ONCE
ll_l'l_
1:-'
ADVANCE
ON
rut:
D
{~
G
SELECT LOCK SET?
YES
18. THE SUPPRESSOR
(See Fig. 24.)
\
~~·
.., TWICE
HEATING
ONCE
ON
ADVANCE
=
GJ
D
SELECT
(a) Unscrew the two slotted M 5 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 strips 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 a new suppressor and re-assemble in the reverse order.
Refer to the electrical wiring diag1ram (Fig. 11) to ensure
the correct connections are made.
19. TO REPLACE THE PROGRAMMER
(See Fig. 26.)
(a) Remove the rear cover of the facia panel by releasing the
four M5 screws, two at the top and two at the bottom.
(b) To remove programmer unscrew the four screws securing
it to the fascia, two at the top, two at the bottom.
(c) Fit the replacement programmer and re-assemble in the
reverse order. Use only the specifi<ed programmer. Do not
attempt to fit any other model or make.