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Page 14
FLOAT LOW WATER CUT-OFF
The fl oat style low water cut-off is only offered as an
option on 8-Series boilers. This control consists of a
fl oat in a chamber that operates a switch. The chamber
is plumbed to the boiler at the minimum safe water
level. If the water drops below this level the fl oat opens
the switch and turns the burner off. If the switch has a
second set of contacts a water feeder can be turned on
to automatically refi ll the boiler to the minimum level.
This control requires regular maintenance to assure
reliability. It is recommended that the fl oat low water cut-
off gets "blown down" weekly to prevent the buildup of
sediment. The blow down procedure consists of placing
a bucket under the device and then opening the blow
down valve located on the control while the boiler is
under pressure. If the blow-down procedure is neglected
sediment can build up under the fl oat holding it at a high
water position even though the water level has actually
dropped to a dangerous level. The fl oat low water cut-off
can fail in a "run" condition when this happens leading
to dry fi ring of the boiler. In this event the warranty will
be voided. This device will require periodic disassembly
for a more thorough cleaning and inspection. The
mechanical switches will also need periodic replacing.
Consult manufactures literature for recommendations
on servicing.
CONSIDERATIONS WHEN USING
AUTOMATIC WATER FEEDERS ON
STEAM BOILERS
Every steam boiler at some time will need additional
makeup water. Water levels need to be controlled on steam
boilers to maintain correct steam-chest volume, prevent
dry fi ring or fl ooding. Excessively low water levels can
cause the iron to overheat creating a "dry fi re "condition.
The addition of excessive makeup water can cause the
boiler to "fl ood" leading to a host of system problems and
damage to personal property.
System leaks that cause a continual loss of water will
require the constant addition of makeup water. Dissolved
minerals and oxygen are introduced with makeup water
and can severely reduce the life of a boiler. Dissolved
oxygen in the water can cause internal corrosion of the
cast iron leading to sludge formation and leaks. Mineral
buildup in conjunction with sludge deposits can reduce
the rate of heat transfer through the cast iron causing
overheating and cracking, ultimately leading to boiler
failure. Leaks must be repaired immediately to prevent
this from happening.
8 SERIES BOILER INSTALLATION AND OPERATING INSTRUCTIONS
The addition of an automatic water feeder can greatly
reduce the number of nuisance lockouts due to low
water conditions. When selecting a water feeder
consideration should be given to preventing boiler
fl ooding and the monitoring of water usage as well. A
water feeder usually works in conjunction with the Low
Water Cut-off by means of the alarm terminals. When
the Low Water Cut-off turns off the boiler during a
low water condition the alarm terminals are activated.
These alarm terminals can be used to turn on the
water feeder. The Hydrolevel CycleGard Low Water
Cut-off has a 30 second delay between the time the
probe detects water and when the alarm terminals
are deactivated. If the water feed rate is too great the
boiler can be fl ooded during this period. The Hydrolevel
VXT-120 (120 Volt model) water feeder works well in
conjunction with the CycleGard Low Water Cut-off. It
has selection switches that are used to precisely meter
the amount of water added, preventing boiler fl ooding.
It is equipped with a digital counter that will monitor
water usage. This feature can be used to detect
increases in water consumption.
FILLING THE SYSTEM (STEAM)
Stable water level is a necessity for steam boilers. It
is very important to have boiler water free from oil,
grease, foaming materials etc. Therefore, fl ush the
boiler thoroughly through a bottom drain by introducing
clean water into the upper ports of all sections of the
boiler. After the boiler piping connections are completed
and the boiler can be fi red, the boiler water should be
heated up and surface impurities fl ushed off through a
high connection (1-1/4" tapping provided in heater cover
plate) (see Figures 11 and 12) and then drained through
a bottom opening. The burner should not be operated with
a low water level in the boiler and makeup water should
not be introduced into a hot boiler.
If possible, the heating boiler should be operated for a
time with all condensate returning from the system to a
drain. This will remove impurities from the piping system
which, if not removed early, will eventually enter the boiler
and cause problems. In some instances, more than one
cleaning will be required to obtain a stable water line.
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