QUESTION
In using a double wall heat exchanger using potable water and glycol lines, are there additional safeguards that are standard practice? For example a double wall heat exchanger AND a 20 psi differential between the lines. Is this standard practice or unnecessary?
REPLIES
PEDARRIN2
Plumbing codes typically only dictate the double wall. A larger pressure differential (potable having the higher pressure), while good design practice, is not required.
Heat exchangers for plumbing are typically shell and tube. Double wall is two walls on the tubes. Occasionally, I have seen plate and frame where the plates have a double wall separating the fluids.
It is a code requirement where the heating fluid could have chemicals that are harmful to people to insure if there is a leak in the tubes, no chemicals enter the potable water side.
SOURCE
https://www.eng-tips.com/viewthread.cfm?qid=389705
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