[Shop-talk] tankless hot water

[Matt]

Looking at the archive it appears to have been several years since we batted this around.  I read thru some threads to get the basics.
I put a small electric tankless heater in my shop - took huge wire!  It works great for hand washing but haven't taken many showers out there.

Well, I got a shock this morning with a leak from the attic.  I climbed up to find the water heater catch pan overflowing a little.  At first I thought the tank was leaking but after clearing the drain - ganged with the AC condensate drain, I believe the AC condensate had backed up into the water heater pan.  Well the house if 15 years old and I was thinking abut replacing the HUGE natural gas tank type with tankless.  I will check the temp of the incoming water but it isn't unusually cold even in winter - I don't think it has much seasonal variation.  Since I have gas, a vent and cold and hot water in the existing position I am thinking I will put the unit in the attic where the tank type currently lives.  My brother says the only problem he has is when someone "short cycles" the hot he needs to reset his unit.  He has had his for over 6 years so I expect they may have refined the technology a bit. I also think we will quickly develop the habit to not do that as that is the only problem with leaving it in the attic.

It looks like 9-10 GPM is the general family residential size.  We are down to the wife and I at home but want to size it for having guests.  So does 9-10 GPM / 200K BTU seem OK for a 4 BR/3 Bath home in a temperate climate (near Atlanta)?
Any problems or show stoppers with anyone out there?  I am under the impression that RInnai seems to be the preferred brand.  TIA!

Matt