On 3/15/2013 4:27 AM, Ed Pawlowski wrote:
> "dsi1" > wrote in message
> ...
>> On 3/14/2013 12:35 PM, Ophelia wrote:
>>>
>>> Our unit looks exactly the same as the one Sheldon posted, and of course
>>> does both central heating and hot water
>>>
>>
>> My step-mother said that the houses in her town (Gothenburg?) was heated
>> by water coming in from a hot water factory and distributed by underground
>> pipes. That was the nuttiest thing that I ever heard. Those Swedes!
>
> It is common in big cities like New York and Philadelphia to have steam heat
> supplied by a central location. This is usually done for the large
> commercial buildings down town. not for residential units. Steam can be
> piped fairly long distance with high pressure and a high concentration of
> energy per cubic foot compared to water. Many high rise building use
> steam for that reason.

That's interesting stuff. We're not interested in heating our houses in
the tropics. Cooling is another matter though. For heating water, our
condos use a heat pump which is essentially an air-conditioning system
run in reverse. Instead of purging the hot air into the environment, we
use it to heat water. Oddly enough, the cold air is just shot out of
exhaust ducts. Too bad. I could use some of that cold air.

>
> The highest temperature you can move water is 212 degrees. Steam, however
> can be moved at temperatures exceeding 500 degrees. Then piped through
> pressure regulators at the point of use to a lower temperature.

This makes a lot of sense. The only thing I know about this is that
boilers are famous for exploding in schools and churches - or does that
happen only in movies?

>
>