I have a drilled well which is about 80m deep with a submersible pump. Its about 10m from my basement, where I have a pressure vessel (at 4 bar) and connections to other parts of the property. All pipework is 26mm ID HDPE.
One of the locations is a run of about 35m from the basement, and I get over 60 liters a minute there.
I had an iron removal filter installed on Friday. It has a venturi for injection of atmospheric air into the oxidation vessel. The vendor said I should get a pressure drop of no more than 1/2 bar and I should barely notice the difference in flow rate
I now get 20 litres a minute to the same location. If I bypass the iron filter, it is back to 60. Clearly I notice the difference in flow rate 🙂 I am unsure how to measure the actual pressure differential, but it seems like it must be a LOT more than a 1/2 bar drop to result in such a reduced flow.
I ran the tap for 1 minute before conducting the tests in each case, as I assumed that may be enough time for the pressure to stabilize.
What are my options here? Why would it be getting slowed down so much? The vendor is suggesting removing the venturi and installing an air compressor. Is it likely that would fix the problem? Do I need a larger filter system to deal with the high flow rate? Is this even considered a high flow rate?
Any advice appreciated!
Best Answer
A venturi works (by definition) by means of a flow restriction. In your case, a substantial restriction is needed to reduce the pressure within the venturi to below atmospheric pressure so that it can draw in atmospheric air.
Air compressors are awfully noisy, and I don't recommend going that route unless you're sure the noise wouldn't bother you. If your water tech has a silent compressor, you might consider it.
Other substances besides the oxygen in air could oxidize your dissolved iron and precipitate it, such as potassium permanganate or hydrogen peroxide, but at a cost in money and maintenance. Air is free and unlimited.
If this were my house, I would add a second pressure vessel after the iron filter to give you whatever unimpeded flow you wish up to the drawdown capacity of the tank.