Mich. Admin. Code R. 408.4278 - Relief valves

Rule 278.

(1) Each hot water heater boiler shall have at least 1 officially rated pressure relief valve set to relieve at or below the maximum allowable working pressure of the boiler.
(2) Each hot water supply boiler shall have at least 1 officially rated safety relief valve or at least 1 officially rated pressure-temperature relief valve of the automatic-reseating type set to relieve at or below the maximum allowable working pressure of the boiler.
(3) When more than 1 relief valve is used on either hot water heating or hot water supply boilers, the additional valve or valves shall be officially rated and may be set within a range not to exceed 6 psi above the maximum allowable working pressure of the boiler up to and including 60 psi and 10% for those having a maximum allowable working pressure exceeding 60 psi.
(4) Relief valves shall be spring loaded without disk guides on the pressure side of the valve.
(5) Relief valves shall be so arranged that they cannot be reset to relieve at a higher pressure than the maximum permitted by this rule.

Notes

Mich. Admin. Code R. 408.4278
1979 AC

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