pressure tank problem, water hammer plus

sagebrushsallyOctober 26, 2010

Hi There,

Admittedly, I live in a shack in the desert and our plumbing would best be described as eclectic, but I could use any help and advice anyone can offer.

Our water system consists of above-ground water tanks that go into a recently-installed pump and pressure tank that goes into 3/4 inch copper pipe. We have two outside spigots, one a couple feet away from the pressure tank, and one about 20 feet away from the pressure tank, each with a 1/2 inch hose bib. About 3 more feet of 3/4 inch copper pipe gets you to the bottom of the sink where it splits into a short section of 1/2 inch pipe that connects to the two hoses that connect to the kitchen sink. Theoretically, one of these will someday be hot water but we haven't gotten that far yet.

Here's where it gets weird. When you turn on either of the spigots, everything is fine, the pump/pressure tank kicks on and water flows normally at a good flow. However, if you turn either of the kitchen sink faucets on, the pump immediately begins to stutter on and off rapidly and because our system is so ghetto, major water hammering also ensues. We are working on getting everything strapped down better, but we aren't sure how to fix the pump stutter when you use the kitchen sink.

We went to Home Depot and bought the cheapest new faucet we could find, thinking maybe our old one just couldn't handle the power of the pump, but once installed, the new one did exactly the same thing. We did find that when we removed the hoses and just sent water through the half inch pipe after the split, the problem ceased, so it seems that it is the hoses that connect to the faucet or the faucet itself that is causing the problem.

What it seems like to me is that not enough water is getting through the sink fast enough so there is excess pressure which tells the pump to kick off, but then there is not enough pressure, so the pump turns right back on immediately, then repeat at a pretty fast rate. Does this make any sense?

Can you get larger diameter hoses for the faucet, or have we done something horribly wrong? Any help or suggestions would be gratefully accepted. I haven't had running water in nearly a year, and it sure would be nice...


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If you have a pressure tank the pump should not kick on imedeately. The pressure inthe tank should drop some before the pump kicks on to bring it up again. Typically the range is on at 20 psi off at 40 psi. It sounds like your tank is full of water(waterlogged). There should be an air head in the tank. The air compresses to give this pressure range. WAter can't compress. this causes the pump to rapid cycle on off as the pressure goes up down fast.

The outside spigots probably use enough water to keep the pump from reaching the cut off pressure.

The solution is to drain all the water out of the tank and let it fill with air. Then pump water in again. Some tanks have a bladder in them. If the bladder is broken then the tank needs to be replaced.

    Bookmark   October 26, 2010 at 8:06AM
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Thanks so much for the advice. That makes a lot of sense to me. I will try to sort this today and will let you know the results!

    Bookmark   October 26, 2010 at 3:35PM
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Make sure the pressure tank pressure is set about 2 pounds below the cut-in setting of the pressure switch. In other words, if the pressure switch is 40-60, the tank setting should be 38. Be sure to set the tank pressure when the system has no pressure on it, otherwise the setting will not be accurate.

I would also check out the pressure switch to make sure that the cut in and cut out points are not too close together. I like a 20 pound spread, but some people don't like that much variation in their pressure, so they set the switches with a smaller range. That can cause cycling as well.

    Bookmark   October 26, 2010 at 4:08PM
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We just washed dishes with running water from our sink for the first time since last winter. Joed, you were absolutely correct. I suspect we had a faulty tank from the factory because we have had a problem with a small leak since we installed the pump and pressure tank. I ordered a new pressure tank (which was only about $14) last spring to see if I could get the leak to stop, but didn't have time to install it before we left for the summer.

Today, we removed the old pressure tank and replaced it, and as soon as we reconnected the lines and turned on the pump, it pressurized, then kicked off. We turned on the sink faucet and it flowed in a clean, beautiful stream of water with the tank maintaining utter silence for nearly a minute before it kicked on again.

It is so nice to have running water again.

Thank you so much for your excellent suggestions. We did not have a super accurate tire gauge (2 out of three were stuck and one did not go high enough) but we think we got it ballpark and will double check with a new gauge. The manufacturer's suggestion was 28 psi, so we aimed for that and everything seems to be working dandy.

Thanks a ton, we really appreciate it!!!

sagebrushsally and her sethsquatch

    Bookmark   October 27, 2010 at 1:32AM
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