Low water pressure spells restroom trouble

I WAS ASKED if I would be willing to visit a commercial site where new public restrooms had been installed. The plumber said he hadn't done anything wrong and claimed everything was installed exactly as specified in the plans. The architectural firm was denying any responsibility as was the water company! The owners wanted an independent investigation and asked if I'd be willing to meet with all the

I WAS ASKED if I would be willing to visit a commercial site where new public restrooms had been installed. The plumber said he hadn't done anything wrong and claimed everything was installed exactly as specified in the plans. The architectural firm was denying any responsibility as was the water company!

The owners wanted an independent investigation and asked if I'd be willing to meet with all the parties involved — on the site — at noon the next day. Sounded like an interesting challenge to me. Let's roll!

Just to let you know, we bid this job and lost to the plumber I'd be meeting. No hard feelings; that's business. And I hope you don't win every bid you submit either. As a result, I was already familiar with the job requirements and how things should look on the business side of those public restrooms. The owner asked that I arrive prepared to mediate any disputes.

Upon arrival, the owner and plumber's representative were present and an official from the water company arrived within minutes. The architectural firm and its mechanical engineer declined to attend. When we entered the center mechanical space that divided the men's from ladies' rooms, I was immediately struck by how neatly the plumbing had been installed.

And there in the center was the twinned booster pump array — just as I'd seen it in the specifications — grossly oversized for its task of elevating pressure to flush valves for a handful of water closets and urinals. Once pressure dropped below 40 PSI, the flush valves would stick open and run, which was why we were all gathered. I knew what this booster pump system was capable of producing, how it should operate and, most importantly, the minimum inlet pressure required.

Neither the plumber nor the water company official had any test gauges!

The plumber turned on the power to the booster pumps and they, in turn, began a short-cycling whirling-dervish dance that surely would have resulted in their demise if left unchecked! Their integral liquid-filled gauges told the tale. The incoming water pressure was too low. With just 2 PSI to spare, the low-water-pressure cut-off switch was "seeing" the sudden pressure drop at startup, shutting off the pumps and then bringing them back on as pressure rose again.

Gauges, gauges, who's got the gauges? Just between us, if I were being called on the carpet for an installation like this, I'd arrive prepared to defend myself. Neither the plumber nor the water company official had any test gauges! I retrieved gauges from my truck and verified that the Armstrong Booster Pump gauges were accurate. Next I checked the incoming line ahead of the dual-check backflow preventer, and, as I expected, there was a 4-PSI drop across the checks. I was reading just over 25 PSI.

"Can't be," the water company official declared, "We have at least 50-PSI delivery in this system."

He suggested we move to the meter pit at the property entrance and survey the plumbing there.

Wrestling with the 2-in.-thick castiron lid while wrenching our backs, the owner and I rolled back the lid. Revealed for all to see was a twinned double-check backflow assembly that we'd installed so that water service to the owner's complex would remain uninterrupted if either one of the two required repairs. Slightly lower in elevation than the new restrooms, the water company official suggested I "jump in and check the pressure."

Confined space caution
One problem — that's a confined-space entry. We know this pit all too well from testing the backflow devices. When we test backflow preventers in confined spaces, we first test the air. Even if it tests OK, we still harness our mechanic and attach him to a hoist for retrieval should something go wrong.

We'd tested this pit previously and found it contains no measurable levels of oxygen — a widow-maker! Arrangements were made to return the following morning with proper gear, our ventilation fans and our four-gas tester to confirm conditions in that pit.

The water company official remarked that this facility was " gravityfed," which caught my attention. As I was leaving the area, I noticed the storage tank off to the side in a wooded area, a short distance from the access road.

As I approached the tank, I spied seven equal rings wrapping around its circumference and measured the first one nearest to ground-level. It was 9-ft. high. Adding the dome at the tank's top would result in approximately 75 ft. (7 x 9 = 63 ft. plus the dome). A large diameter pipe at its top served as a vacuum/relief. The elevation here was slightly higher than the meter pit.

Math can be your friend! We obtain 1 PSI for every 2.31 ft. in elevation. We measured incoming water pressure-as 32 PSI in the meter pit ahead of the double-check backflow preventers. Given that the large storage tank is just slightly above that pit in elevation, we know it is just about as full as it can get without overflowing. There's no way the water pressure ever equaled 50 PSI. That's what the mechanical engineer based the specifications on for that Armstrong Booster Pump rig.

The long and the short of it? The plumber did nothing wrong. In fact, his work was very neatly installed with solder joints wiped and pipe sizing as specified. As much as I hate losing a bid to a competitor, it felt good exonerating a fellow plumber when the other parties were looking to point the finger his way.

Dave Yates owns F.W. Behler, a contracting company in York, Pa. He can be reached by phone at 717/843-4920 or by e-mail at [email protected].

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