Quote:
Originally Posted by FDNYDANO18
A whole house unit is less efficient than individual "location" units... thats because you have to run all the cold water out to the faucet... just like my system ,and a old style HWH for that matter. You dont have to store hot water with your system so it saves you money over an old style HWH. My system uses a coil from the boiler to heat the water in the heavily insulated stainless tank so the water thats stored stays hot longer with less effort than an old style HWH.
A location unit give "instant" hot water. In new construction,with the proper planning and budget,its the best thing. Thats all I was sayin.....
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The word efficiency is getting thrown around here alot. Dano, Your indirect system is only as efficient as your boiler (Probably 80%). Sue's Rinnai unit is also 80%. A typical 40-50 gallon gas fired water heater is about 70%. Jeff's Navien is 98% efficient.
What that means is it uses 98% of the heat produced by the gas to heat the water. Only 2% is expelled out the exhaust vent.
Efficiency has NOTHING to do with how much or how fast the unit makes hot water. You can just use a bigger heater to do the same job as a smaller more efficient model.
With that said, I prefer Dano's setup. Indirect water heaters and hot water boilers when designed properly are hard to beat. They are not subject to the flow restrictions that the tankless units are. They are capable of producing over 200 gallons of hot water an hour.
As for the cold water in the pipes. That can be solved with a recirculation pump. Jeff's Navien has one installed from the factory but a recirculation line needs to be hooked up for it to work. Dano, you could have one installed by a plumber and the wait for hot water would be significantly reduced.
Any electric heater is 100% efficient. There is no vent. But electricity takes a long time to heat water and is expensive.