Other Troubleshooting Issues - pick heaters 6X7 Service Manual

PICK VARIABLE FLOW SERVICE MANUAL
Improper servicing can lead to a malfunction
of the heater, and can even result in
dangerous operating conditions. Consult
Pick Heaters or the local representative if
internal servicing is required.
HEATER/SYSTEM ISOLATION
It is relatively easy to determine whether
vibration is due to a problem within the
heater and/or supply lines, or is caused by
a condition in the hot water distribution
system. SEE FIG. 3
HEATER ISOLATION PLUMBING-
INSTALLATION
1. Shut down the heater
2. Remove the temperature controller
and bushing. Install a short nipple
and tee, the same size as the
bushing.
3. Install the temperature controller
with bushing in one run of the tee.
Install discharge piping to the
branch of the tee with a manual
valve in it.
4. Close the heater outlet valve
5. Start up the heater, discharging the
water through the temporary piping.
If the heater runs smoothly in this
configuration, the problem is
elsewhere in the hot water
distribution system.
If the heater continues to malfunction in this
configuration, check the diagnostic table for
solution. IF problem cannot be corrected,
consult local representative or Pick Heaters.
OTHER SYSTEM
TROUBLESHOOTING ISSUES
1. If steam pressure is below specification
or fluctuates, temperature variations and
system vibration can result. A Pick heater
cannot perform properly under these
conditions. Diminishing steam pressure is
often the result of undersizing or restrictions
in the steam supply system. If, as the steam
valve opens, the pressure falls off at the Pick
steam inlet assembly, a restriction in the
steam supply line, or limited steam supply
exists. The steam line strainer basket may be
plugged, restricting steam flow to the heater.
DANGER! Close steam block
valve before servicing the
strainer basket or other steam
line component.
2. Steam lines and valving must be
sized for maximum steam flow
with negligible pressure loss.
Manual "globe" valves if used in the
steam supply piping should be
oversized to minimize pressure
drop.
3. A stuck injection tube piston can
cause system vibration. The piston
must respond to the steam flow
variations which are the result of
changes in the temperature rise r
flow. See injection tube inspection,
Page 13.
4. The water pressure must be less
than the steam pressure. If the
water pressure is close to or greater
than the steam pressure, the heater
can not be made to work properly.
Water temperature variations and
vibration often result if the heater is
operated under these conditions. In
most cases, the water pressure
should be at least 20 psi less than
the steam pressure.
5. If the water pressure is higher
and/or the steam pressure is lower
than originally specified, the steam
valve may not be large enough for
proper operation of the Pick heater.
The flow through the steam valve is
a function of the supply pressure
and pressure drop across the valve.
The steam supply pressure and the
water pressure at the heater
determine the pressure drop across
the valve. If this pressure drop is
less than originally specified, the
maximum flow through the valve
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