high eff. tank type heaters

[Jefflange]

I have been researching several high eff 94% tank type heaters. Natco voyager, Ao Smith Cyclone,Bradford white 99% eff. Since these are all in one tank type units does the eff. decrease with age, due to sediment build up. Is it better to have a system like the hamilton evolution or Advantage 96 that uses a seperate boiler and tank? Any ideas?

[Howard]

The eff. of the tank type will stay higher longer due to the lack of small passages for heat transfer.

[super80]

any comments on tankless water heater?? does it really save gas and efficiency??

[Howard]

Tankless heaters are toys and don't belong in mats. Some of them don't even give you a warrantee if you use it in a commercial applications. Do the math yourself as far as flow rates, most will only provide their stated capacity up to about 3 or 4 GPM. Just one 75# washer will pull 30 gallons in per fill. At 3 gpm that means if you want to have hot water your unit will take 10 minutes to fill that washer, think your customers will wait for that.