Recently, when I turn on the single handle faucet in my bathroom, the first water that comes out is hot. The gas water heater is on the other side of the house and it used to take time for the water to warm up. Now, the first water out is already hot (warm actually). I suspect something is about to go bad. Any thoughts? Thanks.

Is there a clothes washer nearby?

There is not. It is next to the water heater on the other side of the house. 40-50 feet?

This happens in my kitchen. Some water typically sits in the pipes, and it is warmed by a heating vent. That water comes out first and when it is gone, the cooler water comes out of the faucet. I'm guessing that near this sink you may have a heating vent.

Actually, it's not near a heating vent. Just a recent occurrence in the last week. House is about 15 years old. Good theory, though. Thanks.

At this time I don't see this as a problem, unless you are having trouble adjusting the water temperature to your liking. Is this the case? Its often the case in a single handle faucet to have the last water used still in the pipes.

You could experiment by running the cold water, and going back and see what happens when you turn the cold water back on in a few minutes.

Where do you live and what's the ambient temperature been like?

Love in TN. Recent Temps average in 40s

Nothing is going to go bad, but it does appear that the mixing cartridge to the faucet has gone bad. Here, whenever water is used elsewhere in the house/bathroom/kitchen and you have a bad mixing valve hot water can cross over and be pulled into the cold water line. If it was the opposite (cold H20 going into hot), you would probably notice the issue when taking a shower, i.e., a colder shower or sporadic cold bursts during the shower.

Is it a major issue? Well, you are probably paying for hot water to be heated and not used, but my guess is that it isn't enough of a cost issue or inconvenience that you need to go spending a couple hundred dollars pulling a plumber in. On the other hand, if you are handy, you could probably change out the mixer cartridge easily and the cartridge itself may even be under warranty depending on the age and manufacturer of the faucet.

Otherwise, Dontknownuthin could be onto something with the heat vent issue (if you have a forced air heating system), except that it would suggest that you have developed a leak in the heat duct...not so big an issue with heat but if AC is run through the same ducts you'll be finding a leaker at some point.

Back to you...

Mark