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Considerations When Servicing a Commercial Duplex Sewage Pumping System

We get a lot of call from customers requesting that we come visit their job sites that have older commercial pumps systems. We are asked to inspect and prepare a quote, if necessary, for pumps, controls and covers. We are willing to do this to help insure that we are supplying the proper product. If the pump system is really old and unidentifiable, we can often times reverse engineer the system based on the plumbing code and established formulas used by plumbing designers.

Restaurants and commercial kitchens are really hard on pumps and floats, even with a “well maintained” grease interceptor, a lot of grease and fat can collect in the sump and on the floats. Commercial dishwashers and overuse of some cleaning solutions that go down the drain can effect the pumps power cords, seals, gaskets, and anything rubber leading to a shorter product life.

Most property owners or maintenance technicians will call you when they hear an alarm or if they have water backing up their floor drain. Let’s hope it’s the alarm and not the latter.

Typical Duplex Pumping System

Sometimes it’s just a matter of cleaning and adjusting the floats or pumps switches. If the system is set up properly the floats will be accessible and easily removed to be cleaned and reinstalled. If it is a true duplex system, there will be an alternator with a “hand on / off” switch for each pump inside the control box. Some commercial pump systems will have a rod and float set-up with a mechanical alternator. On larger covers there is usually an access opening that the floats can be serviced through.

If you can manually activate one or both pumps and they both seem to draw the tank down, you could eliminate the pumps as being the problem. If you know the amp rating of the pumps and you can test, then you would insure that both pumps are working to spec. Caution: Always disconnect ALL circuits feed the pump and control panel before servicing.

If one or the other pump hums and does not start you could either pull the pump and inspect the base and impeller for clogs and debris or switch the pump power cord to the “good” running side of the panel and see if the humming pump starts, or if it reacts the same way on the “good” side of the panel.

If the pumps are 3 phase electric and you change the power cords, the rotation of the impeller will need to be checked before reinstalling the pumps.

If you are suspicious of the integrity of the control panel you may want to consult a qualified electrician. The sensor floats that operate the control panel can be tested with an OHM meter by simply disconnecting each individual float and lifting it while observing the OHM meter for continuity.

We always recommend that a vacuum truck be brought to the site on a regular basis to clean and wash the tank especially if there is a build up of grease and debris.

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