Per

I see. I'm staying at a very cheap hotel, but it's in August so hopefully any cold water won't matter too much.

Yes. My parents' house is about a kilometer from their heating plant. The pipes are underground and of course well insulated. (Don't really know where my own heating plant is...)

No controls really, besides shutting the water off for the entire household. As far as too hot/cold, well, the water is about 90-95 degrees celsius or so when it arrives. That is of course too hot for showers so some cold water is mixed with the hot to reach a desireable temperature.
As for central heating (radiators) we just turn it to a setting we know wont be too hot, or turn it down if it is too hot.

Yes, each household's consumption is measured.

Loki

I've lived in several rental properties, about half of which had poor hot water heaters. Typically, they're fine for a few moderate length showers, but when several people'd take a shower, it'd might be luke warm and then cold for the last person or two.

In a cheap motel, you might experience fluxuation of the water temperature, but generally the complete abscence of hot water is fairly rare.

Ovazor

Per, the water in the pipe from the heating plant doesn't come from the shower. The warm tap water is generated in a heat exchanger (a device where heat from the hot water from the plant is transferred to colder water circulating in your house) in the building you live in, but this can be done as fast as it is consumed so there are no danger of running out. The same heat exchanger is used to heat the water circulating in your radiators in the central heating.

Each household's heating energy consumption is measured and billed. I don't know about Denmark, but in Finland district heating is easily cheaper than having your own oil burner or using electric heating.

Per

Ah, I see. This certainly isn't my area of expertise.

Invader Tak

Grr. This is exactly how my apartment is now. It is a house converted into 3 apartments. I think 2 of them (one is mine) share a hot water heater.

To make it worse the tenants in the other apartment are college students who seem to take 90 showers a day. It is so annoying to want a shower and not having the water to do so!

elwoodblues

Wow. Weird. You'd gain a lot through centralizing the whole bit instead of having thousands of units doing it, but I'd think you'd lose at least that much having to distribute it.

Well, as long as you're not taking a shower between 10am and 2pm, or 10pm and 3am, you should be okay. Or else those are some weird college students.

wildernesse

One of the last apartments I lived in had a hot water heater that was half the size of normal heaters--luckily for us, we all had different enough schedules that we never had to take three showers in a row.

I guess hot water heaters work well in the US because there isn't always a centralized utility system. My parents have a well (and so does my granmother and most people who have lived in my hometown for a long time), so they're not even hooked up to the local water system.

--tibac

seebs

The way it works, at least around here, is that we get cold water from the water utility company, and we pay for however much we use. Some of that water goes into a water heater.

When we moved into this house, we had a 30-gallon fairly slow water heater. If you tried to take a shower within about 15 minutes of someone running the dishwasher, or the washing machine, or taking another shower, you would run out of hot water.

We got a 50-gallon water heater, and now two showers can be taken in a row.

But yes, a sufficiently long shower will run us out of hot water for a while.

Loren Pechtel

As others have pointed out, hot water is normally heated in the building it's being used in and it's possible to use it up faster than it's being heated.

My experience with this is that if you're having trouble, simply turn up the heat setting on the tank a little bit. That way it starts with more heat in it (you set the shower handle a bit cooler to compensate, the water that actually comes out is the same temperature) and you don't end up running out.
Obviously, if the tank is seriously undersized for the demands being put on it you could have trouble even then. To find this with college students wouldn't be surprising--they often live with more people in a house than expected (or even permitted) by the building codes.

Our system doesn't cope with extreme loads as well as the instant-type water heaters. However, it permits a much smaller heating system to do the job as it can run longer.

Also, it permits recirculators which aren't an option with the instant types. We have one--there's a little pump attached to the tank and some extra pipes were laid during construction. The system wasn't designed properly, one bathroom takes maybe 15 seconds to get warm. All faucets downstairs, though, are warm within a couple of seconds. This is *VERY* nice when washing your hands in the winter.

You can accomplish the same thing with instant type heaters at every faucet, but that means using electrical heat which costs a lot more than gas heat. It also means a lot of equipment and beefed up wiring to support it.

Monkeybot

Having once had to take a freezing cold shower in the middle of January in a bathroom with a window that was jammed open, I can assure you that yes, American households occasionally run out of hot water.

(Although to clarify, this WAS at my grandmother's house, which is like a thousand years old and has crappy plumbing to start with. I've never had that happen in a house that was built after, oh, 1980. And even in the cheapest of hotels I've stayed in I don't think I've ever had to use cold water.)