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Sarah24 12-07-2008 12:45 AM

Insane water pressure in shower!!!
For some reason for the last couple of months, all of sudden the water pressure in the shower will drastically increase (no other fixtures - just he shower). It only happens maybe once every two weeks or so. But it actually creates a wind inside the shower. One time while it was really strong the shower head or pipe behind it made a click noise and then it went back to normal. I know it can't be the shower head itself since that has been replaced three times in the last few months. I don't believe that their is a water pressure regulator of any kind since it's an older home. I'm just wondering what is causing this to happen and can it be fixed easily. There is a shut off valve to the house - should I just turn it down a bit or should I buy something to regulate the pressure? Any suggestions would be appreciated.

monk4270 12-07-2008 07:48 AM

Have you recently done any plumbing throughout the house? It could be air pockets in the pipes being released.

Mike Swearingen 12-07-2008 08:44 AM

It may be an anti-scald device or a water saver restrictor that is malfucntioning.

Sarah24 12-08-2008 11:43 AM


Originally Posted by monk4270 (Post 195041)
Have you recently done any plumbing throughout the house? It could be air pockets in the pipes being released.

We've recently done a lot of plumbing actually, so the air pocket theory could be it. Is it safe for these air pockets to be released? I'm just concerned of a pipe breaking behind a wall.

Nestor_Kelebay 12-08-2008 09:23 PM


If it wuz me, I would have someone listen to your water heater while you're having a shower. Tell them to listen for rumbling, crackling or popping sounds. Maybe put a cell phone in a plastic bag (to keep it dry) and have that person phone you every time they hear a loud noise from the water heater, and see if the noises correlate with the pressure spikes.

If they hear such noises, your water heater may have a lot of lime scale accumulated inside it. Water pockets can form in the lime and eventually the lime encases small amounts of water completely. The heating of that water causes it's pressure to increase tremendously (cuz of thermal expansion), and the bursting of the lime under that water pressure can cause the heater to make all kinds of fun and interesting noises.

Lime scale will form on the hottest parts of a water heater; on the heating element itself in an electric heater or on the bottom of the tank (where the gas flame impinges) in a gas fired heater. Because thermal expansion causes the water pressure to increase inside these encased water pockets, the water inside the pockets may be WELL ABOVE it's boiling temperature (at the heater's pressure) but still be in liquid form because of the much higher pressure inside the water pocket. Such liquids are referred to as "superheated liquids". If the lime scale cracks and releases the highly pressurized superheate water into the tank, the drop in pressure causes the superheated water to immediately flash vapourize into steam as it escapes from the lime, causing a spike in pressure inside the water heater. But as the very hot steam looses it's heat to the surrounding hot water and condenses again, the pressure inside the water heater quickly returns to normal.

If it's a gas fired water heater, the lime scale will form on the bottom of the tank and insulate the bottom of the tank, resulting in the metal there getting much hotter than it normally does. The result is greater expansion and contraction of the metal at the bottom of the tank. That tank is coated on the inside with a coating very similar to the enamel on a steel bathtub, and so the resulting large expansion and contraction of the powder coating at the bottom of the tank results in it eventually cracking, and once that powder coating cracks, then water in the tank comes into contact with the steel tank wall causing it to slowly corrode at that crack. The resulting corrosion of that tank at the crack site spells the beginning of the end of that tank, and also of that hot water heater.

Electric heaters are less susceptible to tank failure cuz of lime scale formation cuz the scale forms on the heating elements which can be replaced.

Go to A. O. Smith's web site at:
click on "Technical Literature" in the links at the bottom of that web page
to get here:
click on "Technical Bulletins" in the links under the title "Technical Literature" to get here:
Read Bulletin # 13, "Mineral Build-up".

Also, on the Bulletin # 13 page, download and read the file named "Why, When and How to de-lime tank style water heaters". Basically, the procedure is to dissolve the accumulated lime scale with a phosphoric acid by connecting a jug of acid to the drain of the heater, raising the jug so the acid flows in, waiting a prescribed time, then lowering the jug so the acid flows out. You just keep doing that until the acid flowing out isn't full of CO2 bubbles and foam from dissolving lime.

wrangler 12-09-2008 05:27 AM

Also, as you have done alot of plumbing in the last few months, you turned the water main on and off... I've seen this cause particles of buildup to break free and cause obstructions in valves and aerators. Once, while I was working in a bath, the homeowner said she now no longer had pressure in the kitchen on the hot water. I took the one handle faucet apart and found what appeared to be flakes from the cpvc piping obsrtucting the hot water side. You also said you had replaced the shower head 3 times? Did you remove or alter the waterflow limiter? I had a customer with a problem similar to yours that was caused by the homeowner trying to increase their showerhead water pressure by poking the water limiter into the shower head. This caused it to fall inside the shower head and would sometimes cause a partial blockage, thus changes in pressure.
Just another option to consider.

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