Pump Service; Relief Valve - pick heaters 6X7 Service Manual

PICK VARIABLE FLOW SERVICE MANUAL
Note: Sealant must be FDA approved
when heating potable water.
Thread the injection tube into the double-
end bushing (the bushing should be clamped
in a vise at the flats to prevent damage to
threads.) Use an 8-inch pipe wrench to
tighten securely. Do not over tighten –
excessive force will damage the injection
tube.
IMPORTANT: To avoid damaging the
injection tube, apply the wrench on the
area between the threads and the roll
only. Applying the wrench to the area
containing the orifices may distort the
tube and result in the piston sticking.
Install the bushing and injection tube into
the housing, using pipe sealant on the
threads. Reinstall the steam piping and
union. Securely tighten all joints. The heater
may now be returned to operation.

PUMP SERVICE

The function of the pump is to provide
accurate temperature control over varying
flow rates. The pump creates a high rate of
water flow through the heating chamber and
over the temperature control sensor. This
permits the temperature controller to track
changing conditions and maintain accurate
outlet temperature regardless of water flow.
BASIC PUMP INSTALLATION
CHECKS
Check the flow direction and rotation of the
pump. The arrow on the pump body should
show flow from the temperature controller
to the heater inlet (normally pumping
down.) Be sure the check valve in the pump
loop is installed to permit flow in this
direction. Check to be sure the coupling is
tight on both the pump and the motor shaft if
so equipped. (Models 6X100 through
6X500.)
CIRCULATING PUMP SERVICE
CAUTION: Be sure the pump
motor is turned off and the
electrical supply is locked out
before servicing the pump.
Close water inlet and outlet, and steam block
valves. Drain water from the heater. Refer to
the pump service sheet for detailed pump
repairs. Completely assembled bearing
housings are available from the factory, if
applicable. (Model 6X100 through 6X500)
RELIEF VALVE FUNCTION
The relief valve has two functions: 1) to
dampen pressure spikes, and 2) to permit
steam to enter the heater during
periods when water is not being
used.
WARNING: The relief valve must be set
to relieve at a pressure between the water
and steam pressures. If the relief valve is
removed, plugged or set above the steam
pressure, overheated water or steam may
be discharged into the downstream
piping. THIS COULD CAUSE DAMAGE
TO THE EQUIPMENT, OR COULD
RESULT IN SERIOUS INJURY. ONE
POUND OF STEAM HAS A VOLUME
OF ALMOST 27 CUBIC FEET WHEN
DISCHARGED INTO THE
ATMOSPHERE.
When water is not being used and all outlets
are closed, the heater and associated piping
become a closed, filled chamber. As the
pump loop cools, the temperature controller
calls for steam to maintain the set
temperature. Initially, steam can not enter
the heater. As the steam valve opens, the
pressure in the heater increases until it
reaches the relief valve setting. At that point
water exits through the relief valve allowing
steam to enter and heat the water in the
pump loop to the set temperature. The
temperature controller then closes the steam
valve.
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