Pressure Tank Problems?

[keels]

Hi Guys,

We just had a water softener and RO system installed in our house. After we had the systems installed we've noticed a drop in water pressure, especially to the upstairs shower. Is this normal to experience a drop in water pressure after a softener is installed?

I'm also wondering if there might be a problem with the pressure tank. If I turn a tap on and leave it running I've noticed the tank turns the pump on when it gets to 28 psi (which I believe is normal). The pressure gradually increases until it hits 40 psi (approx. 4 - 5 seconds) and then spikes to above 50 psi very quickly. After it reaches 50 psi, the pump turns off and the pressure in the tank drops rapidly to 35 psi (1 second). Once it hits 35 psi a slow decrease in pressure is seen until the pressure gets to 28 psi and the whole process starts again.

Is this normal behaviour?

Thanks, Ryan

[TDHofstetter]

It sounds like the internal diaphragm is "bottoming out" just before the pump reaches final pressure. That means the tank needs to be recharged with air through the Schrader valve on the top.

There should be instructions on a label on the tank - the instructions will probably call for dropping all the pressure off the tank, then adding compressed air up to a certain pressure, then turning the water on again.

[Ruffnek]

That's a pretty wide range from a low of 28 psi to a high of 50 psi. You might want to bring the low pressure up a bit, although the pump will kick in more often. Water is an almost incompressible fluid so tank pressure will drop rapidly once a faucet is opened.

I've often wondered why water pressure tanks don't have a N2 bladder inside. The N2 would compress under pressure and maintain tank pressure for a long while, even with the pump not running. It would sure save on pump cycling.

[keels]

Thanks for the info guys. I'll check to see if there is instructions on what pressures to recharge the tank to when I get home.

Cody - sounds like you have a good idea with your N2 bladder .... should take that one to market!

[keels]

I tried this out tonight and it seem to help ... after I had drained the water out it only had about 8 lbs of pressure left. Brought it up to 26 and things seem better.

Do pressure tanks normally need recharged like this? or is this an indication that the bladder has a leak?

I'm just trying to determine if I should be budgeting for a replacement.

Thanks again for your help.

[TDHofstetter]

Most likely, there's a tiny leak at the Schrader valve, just like a very slow leak in a car tire (identical valve). You can nearly always fix the problem - in both cases - by buying a valve stem tool (got a little stem with a split end that grabs the valve core) and reseating the valve with a loosen-tighten-loosen-tighten action. Worst case, you replace the Schrader valve (about $3) after bleeding off all the pressure.

It's highly unlikely that the bladder is leaking - they're pretty heavy stuff.

EDIT: This is the tool - you can get one at your local car-parts place or hardware store:

www.amazon.com/Milton-S445-Valve-Tool/dp/B000COMXGS/ref=sr_1_1?ie=UTF8&s=automotive&qid=1260936012&sr=8-1

[fredbelknap]

I've often wondered why water pressure tanks don't have a N2 bladder inside. The N2 would compress under pressure and maintain tank pressure for a long while, even with the pump not running. It would sure save on pump cycling.[/quote]

Cody I have heard that some race cars use nitrogen in their tires. Is there something special that needs to be done before using nitrogen?

[Leo Voisine]

I beleive you can replace the schrader valve. It's the same as a bicycle tire or car tire.

You could buy a bike tire or car tire valve stem and unscrew the schrader valve insides - and put it into your tank valve.

Yeah - just like a car tire can have a slow leak - so can your tank - through the valve.

[keels]

So far so good ... Pressure seems to be stable ... pumps running less ...

Keeping an eye on it.

Ryan