Has anyone tried a tankless hot water heater ?

[Willis]

Originally Posted by 2Susan

Are they only propane?

In the FAQs on their site they say they are only propane. I had the same question. But I think the benefits of tankless would outweigh the advantage of using AC. Besides, this unit only uses propane on demand so it won't be running all the time like a regular water heater.

[BKennedy]

Originally Posted by Willis

In the FAQs on their site they say they are only propane. I had the same question. But I think the benefits of tankless would outweigh the advantage of using AC. Besides, this unit only uses propane on demand so it won't be running all the time like a regular water heater.

Your correct. They make electric and gas versions for your house but the gas versions are much more efficent. Propane would be the only way you would want it for a RV the way I see it. And also it is only on when you turn the hot faucet on. Glad to see this technology make it into RV's Versions for your home have been around for over 15 years.

BK

Team Kennedy

[F and E Damp]

I did some basic engineering calculations on these things and I'm very skeptical. Someone identified a 6.9 gpm flow rate which works out (6.9 * 60 * 8) to about 3400 pounds of water per hour. Assuming an inlet temperature of 45 F and a temperature at the shower head of 115F, a heat transfer rate of 235,000 BTU/hr would be needed for continuous operation with no degradation in temperature (3400 * 70).

This works out to about 92 horsepower (235,000/2545) which converts to 68 KW (92*0.746), or 60Amps at 115V.

All the S&B versions I've looked at have needed 220V wiring - maybe this is why?

I don't have data on the calorific value of propane so I don't know how much you'd have to burn per minute to get the equivalent of 68 KW.

Any other engineers on the forum? Get your slings and arrows out - I may have dropped a 12 or a 60 in there someplace.

If DW wants the hot water to last longer when she showers, maybe a much bigger (40-gallon residential type) water heater would be a better idea.