[Shop-talk] tankless hot water

[John Miller]

> 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!

When we remodeled (oh, gads, 15 years ago) we put in the biggest Noritz 
residential tankless available at the time.   Two adults, one kid (now 
11.)  Need to crawl up in the attic to check on the model/BTU.

It's been great, with a few caveats.

Considerations:

They buzz and clack and roar a bit as they're opening and closing valves 
and firing off burners et al, so if you're locating it near living 
spaces you'll want to consider the sound-insulation aspects.

Your washing machine, dishwasher, etc. suck in a lot of water for short 
periods, so a shower during a load of laundry (particularly if, like me, 
you've introduced your low-flow showerheads' flow restrictors to Mr 
Drill Press) might be a problem.

Also, probably not a problem where you are, but if the water coming out 
of the pipe is unusually cold, you won't get truly hot water once the 
flow rate gets past about 50% of the unit's capacity.

John.