Vacuum SystemsMost of the time I agree with Dan Holohan’s comments in his column, as I come from the Dead Men era and think along the same lines. But I think he missed an important item in regards of trying to pull a vacuum on a system (July 2006).
My experience on these systems was good if the old style control valves had the original graphite stem packing still in them. However, if they were rebuilt with the new style U-CUP packing, we had a problem pulling a vacuum. The U-CUP packing needs pressure from the inside to prevent leaking. You might like to check this out further from other sources to see if this is so.
Vivian (Toots) Smith
Tankless Water HeatersA while back, Julius Ballanco wrote an interesting and educational article (July 2006) on tankless water heaters. He didn’t mention whether the equipment was gas fired or electric, but that didn’t matter with the article’s content. I was surprised he didn’t mention one thing that I discovered when evaluating what to do with the hot water system in concert with a complete mechanical upgrade of an office building.
Analysis of the building’s gas-fired hot water system revealed the energy expended to keep the water hot at the fixtures by circulating it or using electric tracing was so high that the life cycle cost exceeded that for instantaneous electric hot water heaters located in the several bathrooms. Being an old steam engineer it hurt to do it, but I recommended they eliminate the central gas-fired hot water system and install local, instantaneous electric hot water heaters.
Ken Heselton, P.E., C.E.M.
KEH Energy Engineering
More on Commercial VentingRecently, a colleague gave me a copy of an older column by Julius Ballanco on plumbing system venting (Nov. 2006). I would remind the author and his readers that although the Uniform Plumbing Code allows the use of AAVs, there are a number of requirements that have to be met. One very important condition is that the plumbing system shall have a minimum of one stack vent or vent stack extending outdoors to the open air.
When I was schooled, the stack’s purpose was to allow the circulation of air (both ways), in addition to equalizing negative pressure in the system when pipe is flushed. With the code not requiring a building sewer trap and fresh air inlet, this requirement of air circulation becomes even more critical to alleviate unwanted sewer gasses. AAVs shall not be installed in a nonneutralized special waste system. When installed under a sink, I don’t know how the AAV meets the requirement of being six inches above the floor level rim of the fixture being vented.
In conclusion, I agree that AAVs are sometimes useful in unique situations. The dependence on something mechanical when natural means are available seems unnecessary.
Code Enforcement Official
Town of West Seneca, NY
Codes, Licenses, and RegistrationRegarding Julius Ballanco’s column asking “Who is the Code For?” (Feb. 2007), I believe the only legitimate reason for building codes, licensing and registration is to protect public health and safety. As soon as they morph into turf protection or competition exclusion they lose any validity and the practitioners promoting such usage should be ashamed of themselves. I am reminded how plumbers fought to keep plastic out of Frisco, but when they built their retirement lodge, plastic all the way. I believe any code requirement should, ultimately, be validated by engineering rationale.
Walter E. Wallis, P.E.
Palo Alto, CA