Operating instructions
69
X. Service Instructions
A. General. Inspection and service should be conducted
annually, except as noted. Turn off electrical power and
gas supply while conducting service or maintenance.
Follow instructions TO TURN OFF GAS TO
APPLIANCE. See Figures 53, 54, 55, 56 or 57.
B. Maintenance of Low Water Cutoff
1. McDonnell & Miller PS-802, PS-804-24 or Hydrolevel
CycleGard CG-400 only.
a. Drain boiler to point below Tapping 'K'. See
Figure 2.
b. Disconnect wire(s) connecting control and probe.
c. Remove control from probe.
d. Unscrew probe from Tapping 'K'. Inspect for
scale and sediment buildup.
e. Remove light deposits with damp cloth soaked
with vinegar.
f. Remove stubborn deposits using diluted
phosphoric acid (H
2
PO
4
) solution, 3 parts water
to 1 part phosphoric acid. Normal operation will
occur with up to 0.2 inch of contamination. If
scale or contamination exceeds 0.2 inches clean
probe more frequently.
g. Clean Tapping 'K' to remove old pipe dope and
other foreign matter.
h. Apply moderate amount of good quality pipe
dope to probe threads, leaving two end threads
bare. Install probe in Tapping 'K'. Mount control
on probe. Attach wire(s) between control and
probe.
i. Fill boiler to normal waterline. Add water
treatment as needed.
2. McDonnell & Miller 67 Only.
a. Weekly (or more frequently if necessary). Open
blow-off valve to flush sediment chamber. Follow
instructions on Blow-Down Card affixed to Jacket
adjacent to low water cutoff.
b. Annual. Dismantle to extent necessary to remove
obstructions and insure proper function of
working parts.
i. Inspect connecting lines to boiler for
accumilation of mud and scale. Clean as
necessary.
ii. Examine wiring for brittle or worn insulation
and clean electrical contact.
iii. Inspect solder joints on bellows and float.
DANGER
This boiler uses flammable gas, high voltage electricity, moving parts, and very hot water
under high pressure. Assure that all gas and electric power supplies are off and that the
water temperature is cool before attempting any disassembly or service.
Assure that all gas valves and electrical disconnect switches are off before attempting any
disassembly or service.
Do not attempt any service work if gas is present in the air in the vicinity of the boiler. Never
modify, remove or tamper with any control device.
WARNING
This boiler must only be serviced and repaired by skilled and experienced service technicians.
If any controls are replaced, they must be with identical models.
Read, understand and follow all the instructions and warnings contained in all the sections of
this manual.
If any electrical wires are disconnected during service, clearly label the wires and assure that
the wires are reconnected properly.
Never jump out or bypass any safety or operating control or component of this boiler.
Read, understand and follow all the instructions and warnings contained in ALL of the
component instruction manuals.
Assure that all safety and operating controls and components are operating properly before
placing the boiler back in service.