thanks guys for the input .
this is one of those things its better to ask and read as there are so many options ,rusty i sent you a pm as well .
i did not even know about return circulation line,which makes total sense . but was aware of buffer tank.
my pipework on the house is fairly straight fwd , 2 levels , bsmt and main and all pipework goes from central in bsmt and runs in the bsmt ceiling and either drops down or up as needed ,so very short runs overall by fluke.
so thinking i may be ok as main bathrooms and kitchen are say 20 ' avg from tank .
all piping is plastic and insulated say 75%
what got me going was i was at home depot ,theye have a RHEEM 95 unit for $1500 not bad as a new hot water tank is $750 zone
even with the tank we have now 40 gallon hot water does not seam to be a issue ,
this is the unit
http://cdn.globalimageserver.com/fetchdocument-rh.aspx?name=ecosense-condensing-95-direct-vent-indoor-performance-ecosense-condensing-tankless-spec-sheetstainless coils .94 ef
- the more i read is this unit flows 9.5 gpm which is possibley overkill for my house ,so any advise on size would be great.
i looked into the rebate and i need to get it installed by a licenced tradesman as well as take out a permit with the city .the recomended home depot installer quotes $3900 for install but that does give it rebate status.but you know i have to do it myself ,just that kind of guy .
Josh,Rusty bus let me know what you think of this unit as well is it in the same price range and gpm of the units you use