Troubleshooting guide

PV500-23 04-2005 Section 23
16
POWER VT
®
BOILER
MAINTENANCE (con't)
8.
The need to periodically check water level
controls and waterside of the pressure vessel
cannot be over emphasized. Most instances of
major boiler damage are the result of operating
with low water or the use of untreated (or
incorrectly treated) water.
Every boiler is equipped with an electronic low
water cutoff. This device senses continuity
between a probe located in the top of the tank
and the water to verify the presence of water. It
is important to check the operation of this
device periodically.
9. This boiler may be equipped with a float-type
low water cutoff. Since low water cutoff devices
are generally set by the original manufacturer,
no attempt should be made to adjust these
controls to alter the point of low water cutoff. If
a low water device should become erratic in
operation or if it's setting changes from
previous established levels, check for reasons
and correct; repair or replace as required.
The controls operation may be checked by
stopping the water supply to the boiler while
the burner is operating at low fire. While under
constant attendance allow the water to lower at
a normal rate. If a control does not break the
circuit to stop the burner at the proper point,
then SHUT DOWN THE BURNER
IMMEDIATELY.
Do not restart until all cross connecting piping
is checked for obstructions. Also check the
float bowl. If these are clean, repair or replace
the control. Repeat the above test to insure
proper operation prior to returning the boiler to
service.
Remove the pipe plugs from the tees and
crosses and make certain the cross connecting
piping is clean and free of obstructions.
Controls must be mounted in a plumb position
for proper performance.
Determine piping is vertically aligned after
shipment and installation and throughout the
life of the equipment. The operation of the
electronic low water cutoff may be checked in
the same manner, by bypassing the function of
the float low water cutoff.
10. It is important to blowdown the float low water
cutoff devices when supplied. It is
recommended that a short blowdown be
conducted daily. Float low water cutoffs should
be equipped with test-n-check valves to allow
blowdown of low water cutoff without requiring
complete drainage of the boiler.
11. A boiler used for heating or seasonal loads or
for standby service may have an extended
period of non-use. Special attention must be
given so that neither waterside nor fireside
surfaces are allowed to deteriorate from
corrosion.
There are two methods of storage – wet or dry.
Your water consultant or feedwater treating
company can recommend the better method,
depending upon circumstances in a particular
installation. Section VII of the ASME Code also
contains information relating to laying up a
boiler.
12. Extended shutdown of the boiler and restarting
are as follows:
1. Turn off all power and fuel supplies.
2. Enter boiler into dry storage.
3. Tag power switch(es) that fuel is off
and tank is in storage condition.
4. Remove tank from storage and turn
fuel and power switch(es) on to start.
Reset all controls and conduct startup
of the boiler as discusses previously.