Descaling The Heating Unit - Potterton Medway Super Installation And Service Instructions Manual

6. REPLACEMENT OF PARTS – Page 16
16
6.10. HEATING UNIT
a. Gain general access - see 6.2.
b. Drain the appliance - see 6.6.
c. Remove the 2 screws securing the energy cut-off device
to the heating unit (located top front left).
d. Disconnect the 2 unions.
e. Remove 4 screws securing the unit to the chassis.
f. Carefully pull the unit from the top and lift. DO NOT lose
the 'O' rings and washers.
g. Remove the primary flue, secured by 4 screws (2 front,
2 rear).
Fig 32
6.11.

DESCALING THE HEATING UNIT

WARNING: ACID/WATER SOLUTION MUST BE USED
WITH EXTREME CAUTION. TAKE CARE NOT TO SPLASH
ONTO SKIN OR INTO THE EYES. WASH ANY AFFECTED
AREAS WITH LARGE AMOUNTS OF COLD WATER AND
SEEK MEDICAL ADVICE.
CARRY OUT THE FOLLOWING OPERATION OUT OF
DOORS. ACID/WATER SOLUTION CAN DAMAGE
FURNISHINGS ETC.
a Gain general access - see 6.2.
b. Drain the appliance - see 6.6.
c. Remove the heating unit - see 6.10.
d. Invert the heating unit on a suitable bench or table.
e. Using rubber tube and acid resisting tanks, assemble as
shown in fig.33.
f. All the upper container with a proprietary brand of
descalent or a solution of 10 parts water to 1 part
hydrochloric acid. The water should preferably be hot,
then add ACID to WATER, not water to acid.
g. Adjust the pinch cock and allow the fluid to slowly pass
through the heating unit into the collecting tank.
h. Continue the process until the fluid ceases to bubble. It
may be necessary to replenish the solution.
i. Disconnect and thoroughly wash out the heating unit
with clean water.
Fig 33