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IX System Piping
A. General System Piping Precautions
WATER QUALITY AND BOILER WATER ADDITIVES
IMPORTANT NOTE
The heat exchanger used in this boiler is made from stainless steel coils having relatively narrow waterways. Once
lledwithsystemwater,itwillbesubjectedtotheeffectsofcorrosion,aswellasfoulingfromanydebrisintroduced
from the system. Take the following precautions to minimize the chance of severe heat exchanger damage caused by
corrosion and/or overheating:
1 Flushthesystembeforeconnectingtheboiler-Inareplacementinstallation,ushingthesystemwillremove
impurities,suchassediment,solderux,metalshavings,andtracesofoldboileradditives.Evenifthesystemis
new,donotomitthisstep–newsystemswillcontainuxandmayevencontainsomeoftheotherimpuritieslisted
above. Flush the system completely and repeat if necessary to completely remove these contaminants. If necessary,
a cleaning agent may be used to assist in system cleaning. See Part XI (“Start-up and Check-out”) for recommended
cleaners.
2. Make sure that the system is tight - This is the single most important guideline. Tap water contains dissolved
oxygen which causes corrosion. In a tight system, this oxygen comes out of solution and is quickly removed from
the system through the automatic air vent. The system then remains essentially free of oxygen. If the system is not
tight, however, frequent additions of make-up water can expose the heat exchanger to oxygen on a continuous basis.
In addition, frequent additions of hard make-up water can cause calcium deposits to collect in the heat exchanger,
causing severe damage. To minimize additions of make-up water:
• Inspectthesystemthoroughlyforleaksbeforeplacingitinservice.
• Ifthesystemincludesundergroundpiping,orotherpipinginwhichaleakmightgoundetected,consider
isolating the boiler from the system with a heat exchanger.
• Makesurethattheexpansiontankisproperlysizedandingoodcondition.Ifitisnot,thereliefvalvemay
open frequently, resulting in regular additions of make-up water.
• Ifanautomaticllvalveisinstalled,installationofawatermeterinthelllineisstronglyrecommended
so that routine additions of make-up water can be detected and their cause corrected.
3. Non-Metallic Tubing - Even if the system is tight, oxygen can be introduced into the system through some
types of non-metallic tubing used in radiant or snow melt systems. Other nonmetallic tubing is equipped with an
oxygen barrier to prevent migration of oxygen into the water. If the boiler is to be installed in a system containing
non-metallic tubing without an oxygen barrier, it must be isolated from the boiler with a heat exchanger as shown in
Figure 9.10.
4. Water Chemistry, Antifreeze, and Boiler Water Additives – Improper boiler water chemistry can cause the heat
exchanger damage described above, as well as deterioration of seals. Observe the water chemistry requirements
shown in Part XI (“Start-up and Check-out”).
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