Pressure-Balancing Unit (PBU)

K-304 or K-15701 PBU Installation

Discard the thick washers (#1 from Fig. 1). These washers are only used when installing a PBU in the Coralais® K-15877 valve.
If installing a new PBU with an existing mixer cap, install the medium O-rings, (#2 from Fig. 1), and large O-ring, (#4 from Fig. 1), onto the existing mixer cap (Fig. 2).

NOTE: If installing a new mixer cap with a new PBU, the new mixer cap will include the new medium O-rings and large O-ring.

Place the small O-rings, (#3 from Fig 1), on the back of the PBU. The PBU location for the O-rings is oval shaped but the small O-rings are flexible enough to fit into the location (Fig. 3).
Proceed by reinstalling the PBU and mixer cap into the valve body.

Discard the medium O-rings, (#2 from Fig. 1), as the Coralais K-15877 mixer cap does not use these O-rings.
Place the small O-rings, (#3 from Fig. 1), on the back of the PBU. The PBU location for the O-rings is oval shaped but the small O-rings are flexible enough to fit into the location (Fig. 4).
Place the thick washers, (#1 from Fig. 1), on the front of the PBU (Fig. 4).
Install the large O-ring on the back of the grey PBU adapter plate (Fig. 5).
Reassemble the remainder of the valve (Fig. 6).