Indirect water heaters have a limited hot water supply and require flushing two issues a tankless heater is less prone to.
Tankless coil vs indirect water heater.
Oil gas electricity propane solar energy or a combination of any of them can fire the indirect systems.
In terms of energy efficiency standpoint the on demand heaters and indirect systems are equal.
Tankless water heaters can provide a certain number of gallons per minute based on their rating indefinitely.
When it comes to energy efficiency both indirect heaters and tankless systems are almost equivalent.
A tankless coil water heater provides hot water on demand without a tank.
Tankless coil water heaters are most efficient during cold months when the heating system is used regularly but can be an inefficient choice for many homes especially for those in warmer climates.
In fact due to their small size tankless water heaters can be mounted on the wall.
However tankless heaters usually run off on either gas propane or natural gas or electricity.
Also by providing hot water only when it is needed tankless water heaters waste less water and eliminate standby losses associated with maintaining a tank full of hot.
Indirect water heaters can be powered by electricity gas solar or a combination of these.
50 more efficient than gas electric water heaters.
On the other hand tankless systems are oil electric or gas fired.
The most obvious difference between an indirect and tankless heater is the existence of a tank.
Tankless water heaters compact in size take up less space than tank style water heaters.
May require a backup system for cloudy days or high demand times.