Random nuggets: More gems from the vaults of the UPC
Let’s begin with a question: Is island venting only permitted for kitchen sinks? From a historical standpoint, the language accommodating island fixtures was first added to the Uniform Plumbing Code in 1958 (bet you didn’t know that) and except for a couple of additions the language has remained the same.
2015 UPC Section 908.0 Special Venting for Island Fixtures
909.1 General. Traps for island sinks and similar equipment shall be roughed in above the floor and shall be permitted to be vented by extending the vent as high as possible, but not less than the drainboard height and then returning it downward and connecting it to the horizontal sink drain immediately downstream from the vertical fixture drain. …
This code section starts with sinks but also includes “similar equipment,” which is undefined. As a matter of fact, the definitions of “sink” and “island” are not found in Chapter 2, Definitions.
Imagine a plumbing fixture floating two to three feet above the floor. Now imagine that same plumbing fixture five or six feet from an adjacent wall that could have waste piping in it with which to connect the plumbing fixture. However, there is no partial wall or structure of any kind to run the plumbing through to get to that adjacent wall. Big problem?
Not really, because of the concept of an “island fixture,” one that is remote from a plumbing wall and requires special venting design, is described in the remainder of the section shown above. But what I want to reveal, in case you never considered it before, is this special venting is not restricted to kitchen sinks.
If you look at the wording in the code section, they all refer to a sink installation. We can see the wisdom of the UPC technical committee: “similar equipment”. Two words and we see the noose being loosened — with several other possibilities. For example, while you may have imagined only using the special design for a kitchen sink installation, what other fixtures might be mounted in a remote island and is that all that is required to make them a similar fixture?
Just to be on the safe side, before you start installing those “similar fixtures” you need to make sure your AHJ is on the same page. Telling them some nut-job you read in this magazine said you could do it is probably not going to cut it.
Two related water heater nuggets
2015 UPC 507.5 Drainage Pan. Where a water heater is located in an attic, in or on an attic-ceiling assembly, floor-ceiling assembly, or floor-subfloor assembly where damage results from a leaking water heater, a watertight pan of corrosion-resistant materials shall be installed beneath the water heater with not less than 3⁄4 of an inch (20 mm) diameter drain to an approved location. Such pan shall be not less than 1-1⁄2 inches (38 mm) in depth.
After reading that section you should observe that water heater drainage or safety pans are not always required. Conditions and locations where they are required are listed but it is the language “where damage results from a leaking water heater” that has installers trying to cover all the bases by including a water heater drain pan with every installation.
However, the damage talked about in this section is not damage to the stuff in the garage in the boxes you haven’t unpacked since you moved in 10 years ago. This is talking about structural damage to the building, floors and wall surfaces. One last thought; the drainage pan isn’t protecting much if the drain on the pan isn’t connected to any piping.
2015 UPC 608.5 Discharge Piping. The discharge piping serving a temperature relief valve, pressure relief valve or combination of both shall have no valves, obstructions or means of isolation, and be provided with the following:
Skipping over six other requirements gets us to from a relief valve into a water heater pan shall be prohibited.
We could argue about many sections and exceptions in the UPC but not this one. The aforementioned water heater drainage pan is not an acceptable location for the terminal end of the temperature and pressure (or any) discharge piping.
Think about it: the water heater discharge pan shall not be less than 1-1/2 in. in depth. Let’s say that in this case it is and let’s say with the water heater located inside and sitting on the bottom of a 22-in. pan, there is 1-1/2 in. of clearance all the way around the inside of the pan.
I calculated the volume left in the pan would be 144.9 cu. in.: 144.9 cu. in. equals .63 gal. When a temperature and pressure relief valve discharges at its maximum, let’s presume it is at 50 psi and the drainage pan will be discharging by gravity.
Do you see a problem with that scenario? At 5 gpm it will take eight seconds to fill the void in the pan and begin to overflow. But, but there is a drain. Yes, and it will give about three seconds additional, so within 11 seconds water will be spilling over the weir of the pan.