Why would room temperature water be coming out of the faucet when I turn on the cold water tap?
August 23, 2007 9:17 AM   Subscribe

When I turn the cold water tap, the faucets in my upstairs bathroom are putting out room temperature water. How do I fix this?

No other faucets in the house appear to be doing this. These are two sinks that are part of a double bowl vanity in our master bath. The hot water works fine. Cold water appears to come out of the bathtub and shower fine too. The water coming out of the faucet when the cold tap is turned is not murky or unpleasant or anything, it just isn't cold. Any advice would be appreciated. I can answer questions, but I am not very handy so I may not know many of the answers to them.
posted by ND¢ to Home & Garden (15 answers total)
Move north? I don't mean to be flip, but I live in the South as well, and it's rare for me to get truly cold water out of the faucet at this time of year. The water that comes out of sink faucets is what's been sitting in the pipes, which are sitting in the hot ground. This would make additional sense since it's your upstairs faucets, which are presumably farther away from the main lines.

What happens when you let the water run for a bit? Does it get cooler after a minute or so? Maybe you just need to let the tepid pipe water flow through -- similar to how it takes longer for the hot water to get from the tank to the sink in cold weather.
posted by pineapple at 9:32 AM on August 23, 2007

So, you are getting nice chilly water on all taps, except this one, even when you let it run for quite a while? It could be that the line for this tap is right next to a hot water pipe. But after, say five minutes, any heating of the cold water pipe from other sources should be negated by the volume of cold water coming through. The only other way I can think of for this to happen is if there is a mixing valve somewhere in the line, in which case it would not get cold no matter how long you run it. This might have been installed for the purpose of delivering room-temp water to the toilet, which would keep it from sweating. If the lines for the taps are plumbed off the toilet supply line, you'd be getting the "tempered" water there, too. Check this by following all the lines back -- somewhere in the basement, crawl space, utility closet or whatever you have, or maybe right in the bathroom under the vanity, you would see hot and cold lines coming together into the mixing valve. This would not likely be buried in a wall. If you find it, a plumber can rectify it.
posted by beagle at 9:34 AM on August 23, 2007

Is this a new development? How long have you lived in the house?
posted by The corpse in the library at 9:42 AM on August 23, 2007

Response by poster: I am getting cold water from all other taps in the house. Letting the water run for a long period of time does not make it any colder. I have lived in the house for 13 months and I would say that this started about two weeks ago.
posted by ND¢ at 10:21 AM on August 23, 2007

Check the insulation on your pipes.

I don't know how the USA is set up, but in the UK we have a tank in the loft, that supplies all of the coled water to the house. Another tank off that supplies water to the boiler/heater. If it's hot in the loft space, the tank naturally absorbs some of the heat. It could be that some of the insulation is loose/missing, and it's absorbing heat from somewhere.
posted by Solomon at 10:30 AM on August 23, 2007

Started two weeks ago.

Mmm. That's a new wrinkle. Nothing else changed two weeks ago? Maybe an area you stopped air-conditioning?
posted by beagle at 10:42 AM on August 23, 2007

Response by poster: No the level of air-conditioning has remained constant. It was about two weeks ago that the average temperature went up to about 107 though.
posted by ND¢ at 10:50 AM on August 23, 2007

How long is "a long time"? For a regular faucet, esp. with a restrictor, it can take three or four minutes to get down to street temp.

Last winter, I was called out to diagnose why the hot water system in an office building wasn't staying hot, even with the recirculation system. Turns out, the ground was being an incredible heat sink, and after running it for four days, everything was peachy.

In your case, though, I'd suspect that a shower valve or some other mixing valve is leaking across. Check the stops at the wall on the two sinks in question - are they cold?
posted by notsnot at 11:02 AM on August 23, 2007

Response by poster: I think that I let them run, at the longest, for a minute. I am back at work now, but I will check the stops when I get home. Thanks.
posted by ND¢ at 11:04 AM on August 23, 2007

Yeah, you've got to let them run for a long time to really get full temperature. Good plumbing design calls for water to be no more than 8ft/s (to keep down shock), and that's in the middle of the pipe (at the pipe-water boundary, the speed is zero). Also, feel the walls that the pipes run in - if they're still hot due to connection to the attic, or for whatever reason, you're going to have hot pipes. For that matter, if the piping is overhead on the second floor, which is certainly not unheard of, they might be running adjacent to your attic, where I guarantee it's hot as balls.
posted by notsnot at 11:24 AM on August 23, 2007

Could be a broken check valve (a valve you find in the back of anything that mixes cold & hot water with one controller). We have the same problem though sadly I've been unable to figure out which valve it is & don't facy ripping up both our showers.
posted by media_itoku at 12:31 PM on August 23, 2007

What happens if you run both sink taps for say five minutes? Does one get cold and the other stay tepid? If so you could have a failing valve in the tap that stays tepid that is allowing a small amount of hot water to mix with the cold. This leads to tepid water in the failed tap. And it's every so slightly possible you could be feeding the good tap with hot water from the bad tap. By running both taps you would eliminate the possibility of the cross feed to the tap that gets cold. This is the only thing I can think of that would get you cold water in the shower but not in the sinks and have started suddenly.

I guess you might also have your pipes feeding the shower and then running thru or near unconditioned space before reaching your sinks. This might couple the tepid cold water with the recent hot weather.
posted by Mitheral at 12:54 PM on August 23, 2007

Are theses particular pipes routed through an outside wall? Say, a south-facing wall? Could be they aren't very well insulated and are losing their "cool" with the heat radiating through the wall.
posted by Thorzdad at 1:25 PM on August 23, 2007

Response by poster: I believe that they are routed through an outside wall, but it would be a North-facing wall.

When I get home I will let them run for five minutes and see if it gets cold. If so, then I suppose that it is just warm water in the pipes, which is fine. I am less worried about not being able to brush my teeth with icy-cold water than that there might be something wrong with my pipes.
posted by ND¢ at 1:38 PM on August 23, 2007

Think about the amount of water that has to move through the pipes from the point they enter the house until they reach the faucet.

I've got a shower in the master bedroom (at the opposite end of the house from the water heater) that can take minutes to access hot water...

I think it is unlikely you can do anything about this except learn to live with it when the weather is that hot...
posted by HuronBob at 6:17 PM on August 23, 2007

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