Comment on Why is there steam coming out of the streets in New York
Evil_Shrubbery@lemm.ee 6 days agoAfaik it’s not inefficient if the heating is done via fossil fuels as big furnaces (especially in the past, especially turbo-fan super-fine grind coal ones) are much more efficient than smol ones for individual buildings (even if the buildings are giant).
Hikermick@lemmy.world 6 days ago
It’s terribly inefficient. The efficiency is lost when the steam that condenses back into hot water is lost and none of it is returned to the boiler to be reheated. Rather than reheating this returning water which normally is at 120-160 degrees Fahrenheit, fresh water is used which in the winter here is around 56 degrees. Aside from this the cold water taken in contains impurities such as dissolved gasses which cause corrosion and dissolved minerals which can cause scaling that acts as an insulator raising the amount of energy needed to heat the water.
Evil_Shrubbery@lemm.ee 6 days ago
Oh, I didn’t know it was a one-way system in NY.
A weird decision, but I guess it lowered the initial cost a bit?
Septimaeus@infosec.pub 6 days ago
The difficulty was drainage. Isolated steam systems in steam era construction were designed to use gravity for condensate collection. It’s one of the reasons boilers are always in the basement of old buildings.
Steam system engineering was a well-compensated profession. A well-designed system would accurately predict the rate of condensate flow for every part of the building, prior to construction, and reflect these predictions in the slope/grade and diameter of the steam pipes. Inaccurate predictions resulted in problems like pipe knock (aka steam hammer) which you can often hear when you or a nearby neighbor partially close the shut-off valve of a radiator.
Since construction in the city had many elevations and could not be predicted in advance, there was no equivalent solution to facilitate condensate collection. The system had to be one way. And yes, it’s inefficient compared to modern systems, but was innovative in its day.
Hikermick@lemmy.world 6 days ago
I can’t speak for NY but that is the situation in Cleveland. I have a customer downtown on city steam. I watch hot water discharge to a drain at the rate of about 3 gallons a minute and there’s 1440 minutes in a day. When it was built I’m sure they reclaimed most of it (80% return is considered good) but over time the pipe corrodes and you have leaks.