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TR Series
skimmer tapping, remove valve, plug skimmer tapping and refill the
boiler to 622 mm (24
/
") water level. After 15 minute operation, read-
1
2
just level to normal operating level of 648 mm (25
boiler (see figure 9). Check the pop safety valve for proper operation.
Check the low water cut-off operation, see below.
G. The entire process may have to be repeated over a period of a few
days on extremely fouled systems.
LOW WATER CUT-OFF CHECK-OUT
I. Electronic probe type low water cut-off
If this boiler is factory equipped with an electronic probe type low
water cut-off, operation of cut-off should be checked at least twice a
year as follows:
A. While boiler is running, drain down boiler water slowly through
Boiler Drain Cock shown on page 2, just until light goes on. Boiler
should shut down 10 seconds after light goes on.
B. Be sure that it is the low water cut-off and not the room thermo-
stat, pressure cut-out, or other control that has shut off the burner.
C. Refill the boiler and repeat test.
D. Refill the boiler and reset controls for normal operation.
II. Float type low water cut-off
If this boiler is factory equipped with a McDonnell & Miller float type
low water cut-off, the low water cut-off must be blown down
(flushed), at least once a week.
CAUTION: When flushing float type low water cut-off control, hot water
and steam will flow out the blow down valve. Blow down valve is illus-
trated below. (Fig. 10)
A. SPECIAL FLUSHING INSTRUCTIONS
For new boiler installed in old system.
Installation of new boiler may break loose a heavy accumulation of
sediment and scale from old piping and radiators. It is extremely
important to blow down your McDonnell cut-off more frequently the
first week.
First week — 3 times
Thereafter — at least once a week.
B. As boiler water circulates through the float chamber, dirt or other
sediment may be deposited. This chamber is extra deep. But the
only sure way to keep any accumulation from interfering with float
action is to "blow down", or flush out, the control once a week. Do
it while boiler is in operation. First note water level in gauge glass.
NIPPLE 13 x 127
(1/2" x 5") THD AT
BOTH ENDS
TEE 13 x 13 x 13 mm
(1/2 x 1/2 x 1/2")
NIPPLE 13 x
127 mm (1/2 x
5") THD AT
BOTH ENDS
Fig. 10
/
") from bottom of
1
2
16 mm (5/8")
COMP ADAPT
TEE 13 x 16 mm
FITTING
(1/2" x 5/8")
ADAPTER
13 mm (1/2")
O.D. TUBE
WATER LEVEL
648 mm (25-1/2")
OFF FLOOR
10 mm (3/8") MALE
PIPE TO 13 mm (1/2")
OD. COMP . ADAPT.
NIPPLE 13 x 51 mm
(1/2 x 2")
Open blow-off valve at bottom of control; water will pour out,
flushing away sediment. Drain until water is clear — about a pail —
then close valve. If level in gauge glass has dropped, add water to
boiler to restore level.
C. NOTE: Opening blow-off valve checks cut-off operation too.
As float drops with falling water level, burner will stop. After
burner is off and normal operating conditions restored, burner
will resume firing.
D. Be sure that it is the low water cut-off and not the room
thermostat, pressure cut-out, or other control that has shut off
the burner.
PRESSURE CONTROL CHECK-OUT
A.
Check burner to be certain it is ready for firing. DO NOT FIRE into
an empty boiler.
B.
Set thermostat high enough for boiler to make steam. Set the pres
sure control down to its lowest setting. As the boiler starts to pro-
duce steam, the steam pressure will start to build. The burner will
shut off when the steam pressure exceeds the pressure setting
(plus differential if control has this feature).
C.
Adjust the pressure control to a higher setting. The higher setting
should be above the steam pressure in the boiler. This should turn
the burner back on.
D.
Reset the pressure control as needed for the system. The pressure
control should be checked at least twice a year.
REPLACEMENT OF STEAM BOILERS
Anytime an older steam boiler is removed from the heating system and
replaced with a new boiler, there are certain conditions that have to be
examined on the heating system.
A.
Steam systems have a tendency to develop scale inside the wet
return lines and the boiler. The older the system the greater the
accumulation of scale that can exist inside the piping. Therefore, it
is necessary when replacing a steam boiler to check the piping for
blockage or restrictions. Clean or replace the piping as required.
(See special flushing instructions on this page.)
B.
Replace all buried wet return lines.
C.
All equipment (air vents, radiation equipment, etc.) in the steam
heating system should be checked for proper operation. All piping
should be checked for proper pitch.
D.
It is good engineering practice to repack or tighten the packing
nuts on all valves in the heating system.
SPECIAL FLUSHING INSTRUCTIONS
Installation of new boiler may break loose a heavy
accumulation of sediment and scale from old piping
and radiators. It's extremely important to blow down
your McDonnell Cut-off more frequently the first week.
First week – 3 times.
Thereafter – at least once a week.
See CARE & MAINTENANCE section for instructions.
11
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