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Ask a pro: Not hot shower
My hot water supply lasts five to 10 minutes. I'd like to drain the hot-water tank and see what's up, but I can't turn off the cold-water supply to the tank; the red tap spins freely instead of turning on the nut, and the tap nut is cracked so I can't force it with pliers.
I decided to turn off the main cold-water supply, but I have the same problem; the tap won't budge and I'm afraid to force it. Is there a way to fix these taps? Or should I just call a plumber? — Jeff Miles, Edmonton
This is going to be one of those good news/bad news answers, I’m afraid. First, the bad news: if your main shut-off valve is seized, you are definitely in “must call a plumber” territory. The ramifications of breaking a valve or line in your home without the ability to shut off the flow of water would be severe, unless, of course, an indoor swimming pool is in the cards.
Now, for the good news: because your hot water lasts only a few minutes, you likely have an inexpensive repair on your hands. When water is hot but in short supply, you likely have an electric water heater with a malfunctioning bottom element.
Once you get your water shut-offs fixed, it should be an easy and inexpensive repair to replace the bottom element. The bottom element might be encased in hard-water scale deposits. Sometimes the deposit can be removed along with the element; other times, the element is cemented in place and the whole tank may need to be replaced.
Since you will have the tank drained anyway, I’d do some preventative maintenance now: replace both the upper element and the sacrificial diode rod and dip tube. These parts are inexpensive and doing it now means having to drain your tank only once.