Hot Water from Cold Water Faucet

Factual Questions
1

Shower and bathroom sink: Turn on cold water faucet, hot water comes out.
Hot water = 100+ degrees, like water from water heater. You cannot take a shower in water this temperature.

Water runs for 15+ sometimes up to 30 minutes before cold water starts to come out of cold water faucet.

Hot water still comes out of the hot water faucet, but we can’t get the water to a lower temperature, so cannot take a shower until it has cooled down.

As you can imagine, this sucks when you set the alarm clock to wake up, take a shower, and then go to work … and then find out you have to wait 20 or 30 minutes to take your shower.

This only happens very early in the morning, at 4:30am when my girlfriend takes her shower (and yes, she has woken me up to feel the hot water). When a shower happens at 5:30 or 6:00 without a shower happening earlier, it doesn’t happen. (Have our neighbors gone through the hot water in some mysterious cold water reservoir?)

When I tell our apartment manager about the issue, she’s incredulous, and therefore she can’t fathom a solution. She basically says that it just can’t happen, says she’ll tell the plumber about it, and I never hear back from her. Months later, I call and tell her again, she basically tells me that it’s impossible for this to happen, that she’ll tell the plumber, and I never hear back.

It’s been over a year. The issue only gets worse, not better.

So – what can be the actual cause, and what would be the solution?

2

My guess is that your cold water is attached to someone elses water heater. 20-30 minutes sounds about right to drain a water heater. So once you drain their hot water, then you start getting cold water. I’d bet that if you ran your cold water until the it became cool, then (leaving it running) go and ask around, someone else will be out of hot water even though they haven’t used it.
You need to start bugging your landlady like every single day. Get to the point where she knows you’re voice on the phone. She’ll get it fixed sooner that way.

ETA depending on wheather you plan to stay there or not, you might want to contact the local housing authority and ask them what to do next.

3

We had the same problem here until a month ago. It turned out that the shower thermostat had broken causing hot water to fill our pipes. There would be no cold water until the hot water was emptied from the pipes. As soon as we replaced the shower thermostat we were back to normal again.
In short: The cause might be a broken thermostat, the solution a replacement.

4

What’s a shower thermostat?

5

Sorry. A bit of research tells me that I am referring to our Thermostatic shower valve. In Danish we usually shorten it to “thermostat”.

6

I have encountered this phenomenon before.

The water lines were run in the crawlspace above the ceiling and during summer months the lines would attain ambient temperature for that area, HOT!

So the first person to need to use the cold water would have to flush the hot water out to get cold water. When you’re taking a shower at 4:30, you’re the first. When you’re taking it at 5:30, whoever had their shower at 5 was the first.

7

But 20-30 minutes to flush the lines?

8

Yup. In our case that was the norm.

9

Something you might want to do in the mean time, set your alarm for twenty minutes earlier. Get up, turn on the cold water and go back to bed for twenty minutes.

10

Document it in writing to the apartment manger every week until the problem is identified and corrected. Otherwise, you have two problems to solve; 1) a hot water issue and, 2) you not sticking it to the apartment manager all the time until it’s corrected.

11

Q: Does the toilet tank fill with hot water when refilling after a flush? Does the kitchen sink faucet behave normally?

12

Also, does it do it year round, just summer, just winter? Does it happen if it’s been raining or cloudy all day long?

13

For an apartment block? Sure.

Apartments are going to have larger pipes than single residences and not only do you have to drain the hot water, you have to drain the heat stored in the metal pipes as well.

14

Brilliant. I vote for this.

15

Any solution that involves “waking up 20 minutes earlier” is right out. 4:30 is early enough, in my book.
Any solution that involves continuously running the water is also out - I care about water conservation, and it’s 2 gallons per minute. 30 minutes is 60 gallons, that’s a lot of water.

We also have an (occasional) problem of really nasty looking (and smelling) water coming out the hot water pipes, especially on a day where they had to shut off the water to the building for some reason or another.

There are times when this nasty water quality can happen for days. The only “workaround” is to run the hot water for 5, 10, sometimes 15 minutes until it’s clear again. When I ask the manager, she says it’s OK to just run the water since we don’t pay for water here. Again, I like to conserver water, and “someone” has to pay for that, and as the consumer of the apartment, that ends up being me, right?

OK, let’s pretend the pipes in the ceiling are being heated by the sun. Can the pipes really hold 60 gallons of water? That seems like a lot for pipes - 60 gallons is 480 pounds of water.
All of this is assuming that we’re the only ones to use water from the time the sun goes down at 7pm until 4:30 in the morning. It also assumes that the sun is able to heat the water to 100+ degrees without having direct contact with it, that the water stays that temperature for over 9 hours, and that the problem can somehow continue to get worse as time goes on.

From what I’ve read here, I think the closest answer may be from Panurge, about the thermostatic shower valve. Panurge, in the U.S., those are hidden inside the wall behind the shower – we just see the faucet handles. We turn the hot handle, and hot water comes out, and normally when we turn cold, cold comes out. I’ve noticed when I’ve traveled to England and Ireland and Japan that the “thermostatic shower valve” is actually outside and visible.

As far as we can tell, this isn’t an issue in the kitchen sink, just the bathroom sink and shower. So, if it was the thermostatic shower valve, could that also contaminate the cold water for the bathroom sink?

And as far as it being attached to someone else’s water heater … the water heaters in our apartment complex are indomitable. My girlfriend takes a 90-minute shower a couple of days a week (her pampering days), and I can hop in right after her and still take a 20-minute hot shower. I doubt we’re kiping someone else’s water.

16

Rough numbers, but 150’ of 3" pipe is about 60 gallons. Or 350’ of 2".

Note also that the pipes are iron so the heat they’re holding get’s dumped into the water extending the cool down time.

And the pipes don’t have to be directly in sunlight to get hot. Anyone who’s worked in an attic in the summer knows that temps easily top 100. Pipes in a 100 degree environment will eventually become 100 degrees themselves. 100 is a low number btw. It’s usually much hotter.

17

So you’re saying that:
a) Pipes in my ceiling are allowing the water to heat up to water heater temperatures (and we pay for gas to heat the water in the water heater, of course) for free, and
b) They reach this temperature during the day (even in winter) and maintain this temperature throughout the night (even nights where it gets to be 40 degrees outside), and
c) No one else in the complex uses any of the water between 7:00pm and 4:30am, and
d) This is a problem that can have not existed when we first moved in to the apartment 6 years ago, but is able to start fresh a year ago, and grow progressively worse as time goes on

right?

18

This also presumes that no one uses the water during the day, once it’s heated up to this temperature, let’s say 10:00am? So for the vast majority of the day, the water is too hot for anyone to take a shower. As far as we can tell, it’s only at that very early time in the morning.

19

Anyone? Anyone?

(seems like knowing these things is essential to solving yer problem, i.e. ruling out accidental solar heating and other theories offered above)

20

Water pipes are not nearly that large. 3/4" is about max for residential service.