A pressure regulator assembly including a regulator valve, a spring guide, a spring extending between the spring guide and regulator valve for setting operation of the regulator valve, a sleeve coupled to the spring guide, a spring cage coupled to the sleeve, an adjustment stem coupled to the sleeve, a dial assembly coupled to the spring cage, and an adjustment cap coupled to the adjustment stem, wherein when the cap is depressed, interaction between the spring cage, spring guide and sleeve causes the spring guide to selectively rotate between a normal mode and a fast-fill mode. In the normal mode, adjustment of the cap determines an output pressure. In the fast-fill mode, the spring is further compressed by movement of the spring guide to a predetermined setting to provide a predetermined output pressure.

An isolation mounting arm for use with an expansion tank has a passageway with a first end portion, a second end portion, and a medial portion located between the first end portion and the second end portion with the drain port located at the terminal end of the second end portion. A first tee is located in the first end portion with oppositely disposed first and second ports. A second tee is located in the second end portion, with oppositely disposed fourth and fifth ports. A first valve member is coupled to the first port, a second valve member is coupled to the second port, and a third valve member is located adjacent to the drain port. An expansion tank is coupled to either the fourth port or the fifth port with a plug coupled to the other port.