The hot water in my shower was hotter today. Should I be concerned?

September 21, 2010 6:47 AM

The temperature of the hot water in my shower was hotter today. Not scalding or uncomfortable, but hotter than I've felt it before. Why would that happen, and should I inspect the water heater? How do I do that, and what should I look for?
posted by bleary to Home & Garden (13 answers total)

Best answer: I've heard and found that when a lot of hot water is used, the water heaters put out more rather than storing it, and it tends to be hotter as it's coming out right when it's heated up, rather than sitting there. All this is to say, are you or someone else using a lot of water lately?
posted by dubitable at 6:52 AM on September 21, 2010

There may be a threshold setting where it'll heat up to a certain temperature, and let it cool to a lower temperature before kicking the heat back on. Seconding dubitable's observation.
posted by samsara at 6:54 AM on September 21, 2010

Yes, the temperature of the water in a tank-type heater varies over a range as samsara described. If someone used some hot water half an hour before you showered, the influx of cold water to replace the hot water they used could've caused the heater to kick on and heat the water to the highest point in the range just before your shower.
posted by jon1270 at 7:05 AM on September 21, 2010

It's as the others have noted.

In my house you want to be the second one in the shower, not the first. Or run the dishwasher a couple hours ahead.
posted by notyou at 7:18 AM on September 21, 2010

You might look at where the thermostats are set. Both upper and lower. Factory setting is around 125F (sorry do not know C for this) and possibly it is set higher.

For extra safety, turn off the breaker before opening the covers. You will need a flashlight, most likely to see into the area where the thermostats are.
posted by Danf at 7:21 AM on September 21, 2010

And my theory is that the water is exactly the same as is always and but for some reason your skin is feeling it differently. Can you check with a thermometer?
posted by Xhris at 7:23 AM on September 21, 2010

This happened to us and it turned out that someone had knocked the temperature setting on the water heater itself. (We have other things in that room and people are in and out of there occasionally.)
posted by Kimberly at 7:41 AM on September 21, 2010

Do you have curious children in your house? When I was little, I got bored one day and fiddled with the valves under the sink in our bathroom, unknowingly screwing up the water temperature. Are your shower valves exposed?
posted by phunniemee at 7:44 AM on September 21, 2010

Some models of water heaters have the dials completely exposed that look like this one. Like Kimberly noted, it might have been changed inadvertently (in our case, the cats were accidentally messing with it).
posted by puritycontrol at 9:30 AM on September 21, 2010

Best answer: One thing that hasn't been noted is that thermostats can malfunction, although it's usually not the first thing to go on a water heater. A bad thermostat could cause the water to continuously heat or get above the "normal" setting. A safety check would involve taking a quick look at the heater's blow-off valve and see if any water is or has been dripping out of it. If yes, get someone to check it out.
Otherwise one of the above responses is correct.
posted by Mister Fabulous at 10:26 AM on September 21, 2010

I live in an 8-unit building in which the landlord pays for the gas for the water heater. Sometimes when I'm doing laundry (in the same room) I notice that the thermostat has been turned down a bit, so I turn it back up so that my neighbors don't run out of hot water as easily. I don't know if they've ever noticed.
posted by rhizome at 10:39 AM on September 21, 2010

The thermostat can come slightly detached, in which case it's obviously not accurately measuring the temperature, and your water gets hotter.
posted by anaelith at 1:03 PM on September 21, 2010

Response by poster: I marked the first answer best because it seems the likely explanation. Thank all of you for responding. I just bought the house, and it's my first one.

mr bleary washed a few extra dishes that morning, and I guess that's the first time that happened with the right timing, I suppose. I asked him to run some more experiments with a thermometer but he was busy yesterday. :)
posted by bleary at 7:54 AM on September 22, 2010