Loud Backflow

[tab2]

Long time daily reader but too scared to post...

I am student and labor when I can for a high end residential construction company. I am always trying to pick up as much as I can when working but I am here for some help.

The backflow for the ejector pump from my basement has a double thud after pumping the water out. To test it I stood next to the backflow and ran cold water in the sink until the pump kicked on. (A tip from a plumber at the jobsite today so there would be no solid waste.) The device is made by Zoeller Co. and is the green one in the bottom picture:http://www.zoeller.com/zcopump/Products/zcoproducts.htm

So finally my questions are do I need to replace or fix the unit? Is this something I can get my hands or only through a professional? Can I pick another one up at Home Depot thats a different make?

A few more details. The backflow is about 6 feet from the ground, on a vertical 2" ABS pipe. This house was built about 20 years ago and bought from the builder who built the other homes on the street. Problems of all sorts are heard from the neighbors. Hope this sounds right.

Thanks for any advice

[NHMaster3015]

The thud is fairly common. It's usually caused by the water column slamming back against the check valve after the pump shuts off.

[westcoastplumber]

I had this problem with one of my excellent customers in manhattan beach, an expensive beach side house and they used ABS pipe to tie the pump in and did not strap it:eek: when it turned off it shook the whole pipe up the wall.

The only way to get rid of most of the thud was to run cast iron and strap it well, it took care of most of the noise.

by the way, it's a backwater or check valve, backwater valves are for solids, check valves are for water only.

[DuckButter]

Actually...backflow would be for potable water.
RPZ, double check, atmospheric...etc.