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Cold Shower When the Toilet is Flushed?

  • Transcript

    LESLIE: James in Michigan is calling with a question that I bet many of you deal with out there: “How come when I’m in the shower and somebody flushes the toilet it is a freezing shower?” Welcome, James.

    JAMES: Absolutely. I tell you, what a pain. I’m taking a shower and all of a sudden somebody flushes a toilet and I get either scalded or I’m ice cold.

    TOM: (chuckling) Alright.

    LESLIE: And you’re not sure if they’re doing it on purpose or not. (Tom laughs)

    JAMES: I think they might be getting back at the old dad, I guess. I don’t know. (Leslie chuckles)

    LESLIE: Well, you know what you need, James? There’s a type of valve that’s called a pressure-balanced valve. The reason you get the scalding hot or the chilly cold water is because of an imbalance in the volume of water that’s coming out at any one time. I mean you set your mix and then when somebody else calls for water somewhere else in the house – by flushing a toilet, for example – more cold water is diverted to that toilet flush, in this example, and of course therefore your shower mix is now more hot than cold and that’s why you get scalded. So the answer is a pressure balance valve and what a pressure balance valve does is it maintains the mix of hot and cold water that you set regardless of how much flow comes through that valve. So what will happen, in that flush example, is the mix will stay the same temperature-wise; the flow will go down a little bit so you have a little less water to all the other fixtures in the house but the mix will stay the same and, hence, you’ll have no more shocking showers.

    JAMES: Oh, wow. That’s fantastic.

    LESLIE: So now, James, you can go back to filling the pitcher with ice cold water and then when somebody’s in the shower and you want to play a trick on them you just dump it over the top. (Tom chuckles)

    JAMES: That’s great. I’ll do it. Where can I get one of these?

    TOM: Oh, they’re available at plumbing supply stores everywhere. It’s called a pressure-balanced valve. You’re essentially going to have to replace the main shower valve. Do you do plumbing projects yourself, James?

    JAMES: Sometimes.

    TOM: Well, you know, if you can replace the valve; if you can solder and handle the basic plumbing connections you can do it yourself or it’s a job that you might want to get a plumber to do. I’ll give you a little trick of the trade: if you can access that shower wall from the backside – if it happens to back up to a closet or someplace like that – it’s a lot easier to work on it from the back of the shower than it is to mess with tile or whatever other surface you have on the front of it.

    JAMES: OK.

    TOM: Because you’ve got to get in the wall to do the job.

    JAMES: Alright, well you’re awesome. And that has to be on every valve?

    TOM: Just on the shower valve. Just on the shower valve.

    JAMES: You guys are awesome. I love your show. Thank you.

    TOM: You’re welcome, James. Thanks so much for calling us at 888-MONEY-PIT.

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