Which should I use?

[Boris]

I am building a small (120 sq ft) portable cabin for a client. I am wondering about the pros and cons of using a 6 gal propane water heater vs an on-demand heater. Someone told me the 6 gal heater means very short/lukewarm showers, others say that won't be a problem. Obviously, the on-demand heater will be considerably more expensive, so I don't want to go with that option unless I have to.

[ramplum]

It is all math, incoming water temp minus say 110deg. X 2 gpm etc....I bet a one min. shower is all you will get with a 6 gal. tank. you can use a regular 30 gal. and get one with 120VAC if that is the issue. Do the water heater sizing method, all mfgers. have the formula in the book.
Greg Chick AKA Ramplum

[majakdragon]

A 6 gallon heater is going to make for very quick showers. Standard shower head allows 2-1/2 GPM flow rate. Unless the customer only uses it to get wet, shut off and wash, and then turn on to rinse, he will quickly run out of hot water. Still more economical than a tankless unit. I had a 10 gallon electric unit in my travel trailer.