Tankless stand alone replace waterheaters, are not obsolete by any
measure . Are in fact the easiest way to save energy. No standby loss.
Takagi and Bosch have units that use either Piezo Ignition , 2 D cells
, Mine are 2.5 yrs old and still checked high on a battery tester, No
pilot No AC. They also have a model with a mini Hydro Generator
suplying ignition voltage, And have remote upstairs thermostats. My
Bosch 117000 btu for 900$ apx will have a 3.5 yr payback, Great deal.
They are 82-83% efficient and last 20-30- yrs, no tank to rot out.
Obsolete hardly , the way of the future. Your boiler heats water as a
secondary feature, not a primary Efficiency in design. I , one person
cook , shower, and do laundry for 7$ gas in summer. I had an electric
small tank that cost 30 $$ in itself in summer a Month. A 5 yr old
Rheem with extra blanket in a warm basement. Depending on family size
you will save 20 % easily over a tank with one person, maybe 7% with a
Do you run 2 showers ?
Your boiler is probably at 50-70% efficient, and the HW function in
summer 40% efficient at best, There is a 99% boiler out, mnfg ?
You really should have a load calc. Pay for one. If you want to save
more start with a Blower door test and IR Photo of heat loss and
insulate and seal up your house.