please help with an age-old problem

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    • #274020

      The age-old problem: I’m in the shower with hot water and someone showers in the other bathroom and I’m suddenly taking a cold shower.

      How do I fix this?? Can’t we both take warm showers at the same time?

      Thanks!! Anne

    • #288997

      you need to install posi-temp or presure balancing shower valves . this will prevent one unit from taking more water than the other.I would recomend moen posi-temp valves

    • #288998

      There are two types of valves that will solve your problem. One is a pressure balancing valve that compensates for changes of pressure in the supply lines to the valve so you don’t get cold water shock. Another option is a thermostatic temperature control valve. This type of valve has additional features than the pressure balancing valve because a thermostatic valve compensates for changes in supply line pressure and temperature. What this means to you is that if you are are taking a long shower and you are using alot of hot water, with a pressure balancing valve you will need to turn the temperature handle to more hot water as you shower. With a thermostatic valve you select the exact temperature you want, there is a range from 70 degrees to 110 degrees on the handle. As you select the temperature you want, the valve maintains that temperature even as the temperature of the hot water coming into the valve starts to cool. The temperature of the hot water must be at least as hot as the temperature you have selected on the handle of course. Neither a pressure balance valve or a thermostatic valve can heat water. A thermostatic valve costs more but it has many benefits. A pressure balance valve will also provide a safe shower. Grohe has a good explanation on their web site at It’s pretty helpful.

    • #288999

      The shower valves are a great suggestion but will not help if the pipes are of galvanized steel.
      Galvanized steel pipes are notorious for decreased diameter because of corrossion build up over the years.
      When a 3/4 water service pipe is decreased by half the volume of water the problems you are experiencing will happen. When this volume is reduced again by a second shower you will receive “shower shock” or a decrease in temperature to your shower. Do you experience this “shower shock” when a toilet is flushed?
      A good test would be to go to the hardware store and buy a pressure gauge that you can install on the house bibb at the front of your house. Open the hose bibb to view water pressure from the street.
      Now go in and run one shower returning to the pressure gauge to see if it has dropped. Then go in and run the second shower leaving the first shower running, return to pressure gauge to see if it has dropped some more.
      If as I suspect the pressure gauge drops each time the showers run, the gauge may have dropped by as much as 30 or 40#. If this is the case at your home shower valve replacement will not 100% take care of your concerns.
      Sometimes it is the service line from the meter to the house that is bad, other times it involves a re pipe of the entire house.
      Good Luck,
      The Local Plumber
      Tustin, California

    • #289000

      Thank you so much for you reply! I went to Home Depot today and they are sold out of the moen posi-temp valve. I will try again in a week or so. Thanks again!


      Originally posted by ynpmasterplumber:
      you need to install posi-temp or presure balancing shower valves . this will prevent one unit from taking more water than the other.I would recomend moen posi-temp valves

    • #289001

      Thanks to all of you that responded! I will try your suggestions and also test the bibb at the front of the house. My house piping is polybutylene, but luckily I have experienced only one problem (at the valve, which was pretty easy to repair). My house is 10 years old. THANKS again for your replies and thanks for helping to keep me warm.

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