Flow rate, fuel consumption, safety, linking units, and heating efficiency are some of the parameters you would consider while choosing a tankless water heater. The design can be compact, medium or large, depending on the consumption volume and frequency of use. Metal construction with an insulated body and energy-efficient parts saves the heater on power bills.

What powers a Water Heater

Tankless water heaters may use natural gas, propane, fuel oil or electric power. You can also find solar models and those working on fuel oil.
Electric heaters are relatively safe and recommended for small homes. Thermal efficiency is almost 99%. They don’t emit any greenhouse gasses. They are easy to maintain and replace the parts.
Propane and natural gas heaters work at 85% to 88% fuel efficiency. However, modern designs have included the option to utilize flue gas for pre-heating inlet water. Hence the efficiency increases considerably. They are recommended for large homes with multiple points of utilization.
Oil heaters are relatively economical and consistent in heating efficiency. They use direct vent for emission. They work on kerosene, sulfur-fuel oil, diesel, or home-heating oil. They use electric power for starting and switch over to oil. They are recommended for medium size homes.
Solar water heaters need a backup gas supply unit when the sunlight is insufficient. They need different types of thermal panel collectors like the flat plate, thermodynamic, thermal air-collector, and bowl-collectors.

Heater Design

As the name indicates, the heater works on the direct supply of water from the pipes. ASTM and EPA standards guide the design can have the capacity of 35GPM to 77GPM (Gallons per Minute). The ambient heating range will be between 330F and 1100F. The relative humidity can go up to 90% at the optimum temperature range.
You can vary the water pressure from 10PSI to 160+PSI which is stated to be highly efficient for continuous heating. Air ratio of the gas supply system keeps the consumption at optimum levels. If the heater can utilize the flue-gas, it is considered to be highly energy efficient.

Heater Construction and Benefits

The core heat exchanger is made of stainless steel, copper, bronze, or other alloys. Constructing primary and secondary exchangers ensures maximum heat transfer into the flowing water.
The safe and efficient construction includes components like air, fuel, and water pressure valves, inlet and outlet pipes, temperature controls, adapters, and switches. The tankless water heater can supply hot water for bathrooms, kitchen, garages, and other rooms depending on requirements.
They are also being used increasingly for radiant floor heating, though the heating volume is relatively less today. The system is consistent in dissipation rate when the insulation pipes are in proper alignment with the heating panels.

Tankless Water heater Limitations
The heating temperature range may drop when the number of units increases. The initial cost of installation could be higher compared to the other models. However, natural gas and propane-based tankless water heaters can provide efficient heating for large homes, when the number of installations is planned based on the output requirements.