Steam Piping - Crown Boiler BSI Series Installation, Operating And Service Instructions

• Do not use softened water in steam boilers. Accelerated boiler corrosion will result. Tie in fresh water supply
to boiler upstream of a water softener.
• Oxygen contamination of boiler water will cause corrosion of iron and steel boiler components, and can
lead to boiler failure. Check for and correct system leaks.
NOTICE:
Do not use copper for steam piping for the following reasons:
1. High coefficient of thermal expansion can induce mechanical stresses and cause expansion/
contraction noises if not accounted for in piping system design and installation.
2. High heat transfer rate (heat loss) of uninsulated copper piping must be included in normal piping
and pickup factors used to size the boiler.
3. Soldering or brazing pastes and fluxes that end up in the system can cause poor heat transfer,
surging, an unsteady water line and wet steam if not thoroughly removed during the skimming
procedure.
4. Galvanic corrosion of adjoining metal may occur due to dissimilar metals in certain water chemistry if
dielectric unions are not used.
Figures 7.2 through 7.4 shows recommended near boiler piping for most common types of gravity return steam systems.
Additional information on steam system design may be found in the I=B=R Residential Hydronic Heating Guide (Pub. RHH)
published by Air Conditioning Contractors of America (ACCA).
One of the primary purposes of this near boiler piping is to separate tiny water droplets from the steam exiting the boiler
so that "dry" steam is sent to the system. If the near boiler piping is not correct, wet steam will enter the system and the
following problems may occur:
•
Short cycling on low water
•
Boiler or system Flooding
•
Hammering
•
Failure to heat one or more radiators
Avoid the three common piping mistakes shown in Figure 7.5. This applies even if the existing boiler has one of the piping
mistakes shown in Figure 7.5 and appears to be working. If two or more steam mains must be connected to the boiler, connect
a separate take-off for each main into the header between the riser(s) and equalizer. Also note the following points:
1) A size reduction must be made to connect the header to the equalizer. This reduction must be made in the equalizer line.
Do not make this size reduction in the horizontal header.
2) One pipe steam systems require air vents on each radiator, as well as at the end of each main. For the system to work
properly, these vents must be properly installed, sized, and be in good condition. Inspect and replace any defective vents. If
there are no vents at the ends of the mains, install them.
3) The use of gravity returns on a multiple steam boiler installation is not recommended due to potential problems
maintaining a uniform water line in all boilers (even a one ounce per square inch difference in the pressure of adjacent boilers
will cause a 1 ¾ inch difference in their water lines).
4) For installations with condensate or boiler feed pumps, follow the pump manufacturer's selection and installation
instructions. Such systems generally do not require Hartford loops.
5) Do not use a check valve in place of, or in addition to, a Hartford loop on a gravity return system.
6) Pipe the fill connection from a clean source of cold water. When the water supply is from a well, make sure that a strainer
is installed in the well system.
VII Steam Piping
!
WARNING
General Piping Notes
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