Patent ID: 8539983

Claim:
A by-pass valve for a heat exchanger circuit, the by-pass valve comprising: a housing defining a serially communicating first bore, second bore and third bore substantially aligned along a central axis with a valve seat facing the first bore at a juncture between the first bore and second bore and a spring seat facing the second bore at a juncture between the second bore and third bore, the first bore, second bore and third bore forming at least a portion of a closable flow path between a first opening and a second opening in the housing; an actuator located in the housing and having a reciprocating seal disposed for movement along the central axis for engaging the valve seat and closing a valve opening between the first bore and second bore; and a coiled return spring mounted in the housing for urging the reciprocating seal towards the first bore to open the valve opening, the return spring having a first end acting on the reciprocating seal and a second end engaging the spring seat, wherein the second bore and third bore each have a different cross-sectional shape transverse to the central axis.