How to Fix a Cold Shower
LESLIE: Susan is on the line with a cold-water shower that I imagine she doesn’t like very much. Tell us what’s going on.
SUSAN: It’s rather shocking.
TOM: I bet.
LESLIE: I can imagine.
SUSAN: The hot-water faucet in the upstairs shower is the only hot-water faucet that does this – is when I adjust the hot water and it’s right – a good mix with the cold water. Step in the shower, then (audio gap) the hot water stops flowing and the water turns cold. It’s almost like the faucet shut itself off or …
TOM: What kind of water heater do you have, Susan? Is it gas or electric?
TOM: And does this problem exist with any other fixture in the bathroom or the house for that matter?
SUSAN: No. It’s the only one that works that way. The hot – the kitchen does not do that; the other bathroom sinks and faucets don’t do that.
TOM: So this is a single-handle faucet?
SUSAN: No. It’s a – there are two handles. They have separate handles.
TOM: Well, I mean I think you’ve got a bad valve in there somewhere. Because if it’s just happening in one location like that, that’s the only thing it could be. We have plenty of hot water for the rest of the house. I suspect that there’s a problem with the valve. You might just want to replace the faucet set.
SUSAN: Oh, OK.
TOM: That would make sense as to its …
SUSAN: I just wondered why would that do that?
TOM: I’ll just speculate here. As the water heats up the pipe, the metal expands and causes the valve to squeeze shut a little bit or something like that. There are a lot of reasons it could happen but I think it’s mechanical, because it’s only happening in one location, so it has to be the valve.
SUSAN: Oh. That’s correct. Yeah.
TOM: It’s not – there’s nothing mysterious about this. It’s got to be the valve.
SUSAN: Alright. Well, great. Thank you for the diagnosis.
TOM: What you might want to think about when you replace this is talk to your plumber about something called a pressure-balancing valve. Now, I’m not sure if he’ll be able to find this for this kind of configuration that you have.
But what a pressure-balancing valve does is it keeps the mix ratio between hot and cold steady, regardless of what’s happening in the rest of the house. So that if you were to hop in the shower and somebody else flushes a toilet somewhere, you don’t get sort of that shock of hot or shock of cold water as one fixture sort of steals water from the other. It keeps the ratio the same. So while you may have less or more water, the temperature of the water never changes. If you’re going to spend the money on a plumber and valves, I would definitely look into getting a pressure-balanced valve set if I could.
SUSAN: Well, I’m glad to know about that. Thank you so much.