The most insidiously wasteful of energy hot water supply system I became acquainted with working for Sears. Those huge buildings, with restrooms spread all over the place, have TWO pipes run to every hot water fixture, from a huge water heater mounted in a third level above the sales floors. A pump continuously circulates the heated water to all the fixtures, and back again, while the store is open. All that piping is constantly delivering wasted heat inside the walls. Atrocious! Frank
In our modern apartment the hot 22mm feed pipe from the boiler travels full length of the property and back. It doesn't circulate so we have to drain 10 litres of water before it runs hot. Looks like plumbing design internationally needs a good kick up the whatsit. Here in Britain building standards are atrocious. Years ago I asked my father, who was a manager in a building company, what he would do if his new car was delivered full of dents and leaked oil. He shrugged.
@Jim Nash I've often thought about the heat energy lost and wasted by piping while delivering the contents to the user. Such piping ought to be insulated, but never is. I once asked a building contractor why insulation was being installed within interior walls of a home he was constructing, when the temperature will always be equal on both sides of the wall: sound abatement. Go figure. Frank
My heating system, which I hate, involves hot water being piped through every room of the house, yet we have to let the water run for a long time before we can get hot water upstairs.
@Ken Anderson That's interesting, given the fact that heat rises......I suppose one answer might be separate water heaters above and below. When I converted our home from propane to electric, we gained the ability to only turn on the water heater when need was anticipated, the circuit breaker being in our pantry. Frank
A future project will be to replace our water heater with one that is not connected to our home heating system. Unless we shut the boiler off, it kicks on all summer just to keep the water heated, and we still have to wait for the hot water to make it upstairs.
Think it depends ware and how many outlets you have I bought my house in 1967 and to heat the water we had an Ascot (but no C/H) in the Kitchen next to the sink and below the bathroom...almost instant hot water to both and a 15m pipes feed both Years later I installed a Combi and included heating radioters The problem was as some of my neighbours did was to install a Cylinder which the water was heated by a Boiler which gave heating and hot water and a massive back step It meant a Water tank in the Loft to store water to feed the Cylinder and bigger pipe work. You heated the Cylinder about 30 gallons of water and if not used was allowed to lose heat.
That's the kind of heating system we had in the house I grew up in. But the water for the baseboards was heated separately in a furnace. First by oil then by natural gas flames. Water heater was separate and electric. Seems like an unusual setup.
Ours is combined so, even when the temperature is already hot, the boilers will fire up to heat the water anyhow. We plan to separate it so that the water heater is on electric, and not combined with our heating system.
It's interesting to read of your American ways. Here in Britain a condensing combi boiler is the cheapest form of heating and hot water. You lucky souls in California will not be worried about cold weather. Other than the stupid pipe runs our apartment and pipework are well insulated. Even now in winter, with the central heating switched off at 10.30pm room temperature only drops two degrees by morning.
In our master bath, my wife uses the left hand sink and I use the right hand sink. It takes over one minute to get really hot water to my sink, but my wife's sink produces it in 15 seconds! There must be a piping difference feeding the 2 Sinks, the Tub, and the Shower in that Bartholomew! Harry
@Hal Pollner Could there be one of those "instant" water heaters hidden beneath her sink? We have a similar problem: house is 80 feet long, with baths at either end. Water heater located at one end, of course. The "far end" is the Master; my wife won't shower there in Winter, preferring the other bath, due to the length of time taken to produce hot water there. Frank