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B. BACKFLOW PREVENTER
It may be recommended to use a back flow preventer – check local codes. If a back flow preventer or a no return valve is used, a
thermal expansion tank must be installed on the cold water supply between the boiler and valve.
To control thermal expansion, a thermal expansion tank suitable for potable water should be installed in systems with an installed
backflow preventer. DO NOT use a closed type expansion tank. Follow expansion tank manufacturer's specifications to properly size an
expansion tank to the installation. Failure to properly accommodate thermal expansion could result in property damage, severe
personal injury, or death.
C. CENTRAL HEATING PIPING SYSTEM WATER PIPING METHODS
EXPANSION TANK AND MAKE-UP WATER
1. Ensure that the expansion tank is designed and sized to correctly handle system water volume and temperature. Check technical
specifications for water content of this boiler.
Expansion tanks must be sized according to total system volume. This includes all length of pipe, all fixtures, boilers, etc. Failure to
properly size system expansion could result in wasted time, money, and possible property damage, personal injury, or death.
Undersized expansion tanks cause system water to be lost from the relief valve, causing make-up water to be added. Eventual boiler
failure can result due to excessive make-up water addition. SUCH FAILURE IS NOT COVERED BY WARRANTY.
2. The expansion tank must be located following recognized design methods. See expansion tank manufacturer's instructions for
details.
3. Connect the expansion tank to the air separator only if the air separator is on the suction side of the circulator. Always install the
system fill connection at the same point as the expansion tank connection to the system.
DO NOT install automatic air vents on closed type expansion tank systems. Air must remain in the system and return to the tank to
provide an air cushion. An automatic air vent would cause air to leave the system, resulting in improper operation of the expansion tank.
DIAPHRAGM (OR BLADDER) EXPANSION TANK
Always install an automatic air vent on top of the air separator to remove residual air from the system.
Use both thread tape and pipe dope to connect to the 1 ¼" heating water outlet and inlet.
D. CIRCULATOR SIZING
The heat exchanger has a pressure drop that must be considered in your system design. Refer to Table 15 for pressure drop through
the heat exchanger.
WHL-032 REV. 6.2.16
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