34 Pa. Code § 3a.167 – Hot water/steam heat exchangers.

(a) Heat exchangers must be manufactured under the ASME Code.
(b) Heat exchangers must have adequate over-pressure protection to protect both systems.
(c) Heat exchangers used for domestic hot water supply must have a high temperature limit switch designed not to exceed 210°F.
(d) Inspection of hot water/steam heat exchangers shall be performed in accordance with § 3a.111(8) (relating to field inspections).

This section cited in 34 Pa. Code § 3a.3 (relating to scope).