3.2 REPLACEMENT BOILER INSTALLATIONS: PROTECTION AGAINST
CORROSION & SEDIMENT
CLEAN OR REPLACE ALL SYSTEM PIPING
AND HEATING UNITS
Arrange for chemical or mechanical cleaning of
the entire system. A chemical treatment company
should be consulted for the proper means of any
chemical cleaning.
Replace any piping considered to be deteriorated
beyond safe or cleanable condition.
Flush the system clean, being certain to isolate
the boiler.
DO NOT FLUSH THE SYSTEM THROUGH THE
BOILER.
NOTE: For some old systems, there is a
reluctance to clean the piping because of
possible leaks occurring in badly corroded lines.
Should the customer refuse cleaning, it is
necessary to install filtration equipment. Install
either a fibrous filter or a centrifugal filter in the
boiler return piping. This will collect and remove
sediment from the system.
A booster pump may be required to overcome the
additional pressure drop introduced in the line by
the filter. When filling the system, provide
chemical treatment as outlined in Section 3.3.
CAUTION
Failure to properly clean the system or to install
mechanical sediment removal equipment can
result in tube blockage and severe corrosion plus
damage to pumps, controls, and air removal
devices.
Inspect, repair as necessary, or replace system
air control devices.
Install gauge glasses on air expansion tanks and
install a tank fitting in the system connection to
the tank.
Install a strainer in boiler return piping.
3.3 BOILER WATER TREATMENT
PURPOSE OF WATER TREATMENT
Water treatment is required for satisfactory
operation of the boiler. It must be devised to
prevent depositing of scale and corrosion from
acids, oxygen and other such harmful elements
that may be in the water supply.
A qualified water treatment chemist should be
consulted and the water systematically treated.
OBJECTIVES
The basic objectives of water treatment are:
1. Prevent the accumulation of scale and
deposits in the boiler.
2. Remove dissolved gases from the
water.
3. Protect the boiler against corrosion.
4. Maintain the highest possible boiler
fuel efficiency.
5. Decrease the amount of boiler down
time from cleaning.
CONTINUOUS MONITORING REQUIRED
Water treatment should be checked and
maintained whenever the boiler is operating. The
boiler operator should be sure that the boiler is
not operating for long periods without proper
water treatment.
It should be noted that water boilers may well
need chemical treatment for the first filling plus
additional periodic chemical treatment, depending
on system water losses and the makeup
requirements.
Water treatment may vary from season to season
or over a period of time. Therefore, the water
treatment procedure should be checked not less
than four times a year, and possibly more
frequently as the local water conditions may
indicate. All water introduced into the boiler
should be softened and should include an oxygen
scavenger like sodium sulfite. This is required to
remove dissolved oxygen from the water.
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