Mich. Admin. Code R. 408.4270 - Provisions for thermal expansion in hot water systems
Rule 270.
(1)
All hot water heating systems incorporating hot water tanks or fluid relief
columns shall be so installed as to prevent freezing under normal operating
conditions.
(2) If the system is
equipped with an open expansion tank, an indoor overflow from the upper portion
of the expansion tank shall be provided in addition to an open vent. The indoor
overflow shall be carried within the building to a suitable plumbing fixture or
to the basement.
(3) If the system
is of the closed type, an airtight tank or other suitable air cushion shall be
installed that will be consistent with the volume and capacity of the system,
and shall be suitably designed for a hydrostatic test pressure of 2 1/2 times
the allowable working pressure of the system. Expansion tanks for systems
designed to operate at or above 30 psi shall be constructed in accordance with
the provisions of section VIII of the ASME boiler and pressure vessel code,
1983 edition, and its addenda. Provisions shall be made for draining the tank
without emptying the system, except for pressurized tanks.
Notes
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