Rich, my first suggestion is to make it clear in your proposal that you are not responsible for lights dimming whenever somebody turns on a hot water faucet. Second suggestion means less revenue for you, but a good possible alternative. They also make gas powered tankless water heaters. They still sometimes need a 120 volt outlet installed for controls, so you can still make some dough on it, depending on the make and model.
#55494 - 09/01/0507:05 PMRe: Tankless water heaters
We've seen a few of these and I really don't understand why someone would want one. I know they only run when hot water is needed, but they draw so much more than a standard water heater when in use, I doubt there is an energy savings. One of our customers put in one of these with a recirc pump, so it runs constantly. The same customer had us install a steam generator that draws 126 amp constantly when in use. He was surprised when I told him he had to have a service upgrade.
#55497 - 09/01/0509:21 PMRe: Tankless water heaters
One of our customers put in one of these with a recirc pump, so it runs constantly.
Betcha it doesn't last very long. I believe they have a duty cycle or at least are designed for intermittent duty. Also, a recirc pump pretty much goes against what the heater was designed for, that being on-demand water heating. If it's going to maintain hot water there are other much less expensive alternatives such as a conventional water heater.
we installed one of these tho not quite as large. Step one was a service upgrade. The unit we installed came with a panel with the unit. Fed 125A to the panel and it had 3 50A two poles. The controller put power where it was needed in the unit. It had 6 heating elements and demand dictated how much power/how many elements were used. Interesting set up. Rod
#55499 - 09/02/0502:28 PMRe: Tankless water heaters
Oh boy... something like that in the US... here in Europe those beasts are wired across the three phases and still require a 3x35A 400V feed (that's a standard service for a single family building here...) They only have one single advantage... they provide instant hot water where no gas is available. That's the only reason they were invented.
Tankless gas water heaters have been de facto standard here for ages. Apartments built around 1900 and later (the big majority of Vienna's houses) didn't have hot water originally, or if they did it was already tankless gas water heaters. They were invented in 1885 I think. Over the years functionality to add hot water central heating to small wall-mount combi units was added (caught on around the 1970ies). Nowadays you can see such a tankless water heater/central heating combi boiler in almost every renovated apartment and smaller single family home (those combi units serve a floor area of roughly 2000 square feet for heating).
#55500 - 09/02/0502:30 PMRe: Tankless water heaters
It's not a good joke, but I have to add it... in Austria electric tankless heaters are basically unknown, whereas in Germany they seem to be quite popular. And each time somebody shows up at a German board asking: "What line do I ned for a 28kW tankless?" I say: "3/4" iron pipe!"
#55501 - 09/03/0509:07 AMRe: Tankless water heaters
One thing you need to remember with these units is that the output temperature is inversely related to the flow rate. In the U.K. one above, for example, to get water out at 140 degrees you'd be looking at only about 3/4 gal. per minute flow rate based on our average water supply temperature.
According to the specs on that 22kW American unit linked to above, you could get only just over 1-1/2 gals. per minute for 140 degrees out with water going in at 50 deg.
[This message has been edited by pauluk (edited 09-03-2005).]