A.O. Smith HW 610 - Manual (Page 20)

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5. VENT VALVES
It is recommended that automatic, loose key or screwdriver type
vent valves be installed at each convector or radiator.
6. MANIFOLD HEADERS
Split systems with individual supply and return lines from the boiler
room should normally have this piping connected to supply and
return manifold headers near the boiler. To achieve good water
distribution with maximum pressure drop for several circuits,
manifolds of at least 2-1/2" (64mm) diameter are suggested on
HW-399, HW-420, HW-520, HW-610 and HW-670 units. HW-300
units should have 1-1/2" (38mm) diameter manifolds.
The circuits should be spaced on the header at a minimum of
3" (76mm) center to center. Install a balancing cock in each return line.
Manifold headers are recommended for split systems with or without
zone valves and also those installations with zone circulators. If the
system is to be split at remote points, good practice requires special
attention be given to main pipe sizing to allow balancing of water flow.
The boiler piping system of a hot water boiler connected to heating
coils located in air handling units where they may be exposed to
refrigerated air circulation must be equipped with flow control valves or
other automatic means to prevent gravity circulation of the boiler water
during the cooling cycle.
7. COOLING PIPING
When the boiler is used in conjunction with a refrigeration system it
must be installed so that the chilled medium is piped in parallel with
the boiler with appropriate valves to prevent the chilled medium from
entering the boiler, see Figure 13.
Water temperature in the heating system must be reduced to less
than 100 0 F (38°C) before cooling system is started, or damage to
the chiller unit may occur.
SCHEMATIC SHOWING PROPER PIPING ISOLATION
OF THE BOILER FROM THE CHILLER
FIGURE 13.
If the boiler is connected to chilled water piping or its heating coils
are exposed to refrigerated air, the boiler piping system must be
equipped with flow valves or other automatic means to prevent gravity
circulation through the boiler during the cooling cycle.
8. CIRCULATING PUMP
CONSTANT CIRCULATING PUMP OPERATION OF THE BOILER
VOIDS THE WARRANTY. Constant water flow through the unit
will “wash” away the copper’s natural protective coating. This is
called velocity erosion. This erosion is not as great a problem when
intermittent circulating operation is used per the recommended
installation procedure. Constant circulation of water through the
building’s system main is permissible as long as the water does not
constantly flow through the boiler. Only all bronze or stainless steel
circulators are to be used with the unit when it is installed in HOT
WATER SUPPLY SYSTEMS.
A TYPICAL CIRCULATING PUMP
FIGURE 14.
Although each circulator that requires oiling is oiled and operated by
the manufacturer, IT MUST BE OILED AGAIN BEFORE OPERATED.
Oil the three oil cups (2 on the motor, 1 on the pump) as instructed
on the oil tube supplied with the unit, see Figure 14 on this page.
Thereafter, during the heating season, lubricate the three oil cups at
least once every four months. Combination heating-cooling systems
should be lubricated every four months year ‘round.
Use 2 or 3 teaspoonsful in bearing oil cups or 12 drops in the motor
oil cups, see Figure 14 on this page. Use No. 20 non-detergent
motor oil.
Follow the same oiling procedure if a replacement circulator is
installed into the system.
GAS CONNECTIONS
WARNING
THIS BOILER IS NOT INTENDED TO OPERATE AT GAS SUPPLY
PRESSURE OTHER THAN SHOWN ON THE RATING PLATE.
EXPOSURE TO HIGHER GAS SUPPLY PRESSURE MAY CAUSE
DAMAGE TO GAS VALVES WHICH CAN RESULT IN FIRE OR
EXPLOSION. IF OVERPRESSURE HAS OCCURRED SUCH AS
THROUGH IMPROPER TESTING OF GAS LINES OR EMERGENCY
MALFUNCTION OF THE SUPPLY SYSTEM, THE GAS VALVES MUST BE
CHECKED FOR SAFE OPERATION. MAKE SURE THAT THE OUTSIDE
VENTS ON THE SUPPLY REGULATORS AND THE SAFETY VENT
VALVES ARE PROTECTED AGAINST BLOCKAGE. THESE ARE PARTS
OF THE GAS SUPPLY SYSTEM, NOT THE BOILER. VENT BLOCKAGE
MAY OCCUR DURING ICE BUILD-UP OR SNOW STORMS.
WHEN LOCAL CODES REQUIRE A MAIN MANUAL SHUTOFF
VALVE OUTSIDE THE BOILER JACKET, A SUITABLE MAIN
MANUAL SHUTOFF VALVE MUST BE INSTALLED IN A LOCATION
COMPLYING WITH THOSE CODES.
IT IS IMPORTANT TO GUARD AGAINST GAS VALVE FOULING
FROM CONTAMINANTS IN THE GAS WAYS. SUCH FOULING
MAY CAUSE IMPROPER OPERATION, FIRE OR EXPLOSION.
IF COPPER SUPPLY LINES ARE USED THEY MUST BE
CERTIFIED FOR GAS SERVICE.
BEFORE ATTACHING THE GAS LINE BE SURE THAT ALL GAS
PIPE IS CLEAN ON THE INSIDE.