School water heater: Unfinished business? (Background Report)

WE WERE FORTUNATE to find a plumber who made sure to tell us what would need to be done in order to meet the current building code requirements, when our water heater recently failed. That prompted us to consider measures that we were not previously aware of. Out of the four items that he informed us about, we agreed to implement two of them, as described HERE. 

However, we opted to defer the other two items, for three reasons: they would be very costly; they would be needed only in very extreme circumstances that were unlikely in a brand-new system; and we could have them done later for the same price. 

On his written estimate, the plumber then noted the two deferred items explicitly:

Customer understands and agrees that the following items are not included in this estimate and will be completed at a later date under a separate quote/authorization:
• Run T&P (temperature & pressure relief) discharge line to the exterior
• Run drain pan discharge line to the exterior

What I have since learned, however, seems to support our decision not to pay for those two recommended changes.

Below the jump, this post describes those lingering items and their status, in more detail.…

Both of the deferred items have a function only the event of catastrophic failure. 

T&P relief valve discharge line

The temperature and pressure relief valve is a crucial safety feature, as noted by an engineer HERE:

Strict installation requirements are necessary because the materials handled—superheated water and steam—present extreme scalding and explosion hazards.

Currently it discharges down into the drain pan—which seems to be an acceptable configuration, according to one standard code. 

Presumably if our new valve did blow, the resulting hissing and gurgling noise would be heard within the adjacent corridor. Upon opening the closet door, someone could readily see the problem. That’s important, because then they can summon a plumber for help. As the previously cited engineer explained:

This visibility serves as a warning sign that the water heater has experienced a dangerous over-pressure or over-temperature event.

Although our plumber told us that a T&P relief valve needs to drain to the outdoors separately from the drain pan, I have not immediately found corroboration of that claim. Someone ought to check the L.A. City code to be sure. In the meantime, as far as I know, this aspect of our plumbing system is currently okay, so I am content to leave things as they are.

Drain pan discharge line

The plumber had likewise noted that the building code requires an exterior drain from the drain pan beneath the water heater. In the event that the tank leaks catastrophically, there won’t be a flood inside the building. 

DRAIN UNCOVERED.  In our case, after the old tank was removed, a drain hole was indeed visible.… 

Whence exactly it drains still needs to be ascertained—presumably the next time that someone goes into the crawl space beneath the building.