Can it run a whole house?

No. At 18,000 BTU it is sized for one point of use at a time, such as a single shower or sink. A whole house with several bathrooms needs a much higher-capacity unit.

Does it need electricity?

Yes. It plugs into a standard 120 V outlet to power the ignition and controls. The gas supplies the heat; the electricity runs the electronics.

What gas does it use?

It is built for natural gas, not propane. Check that your home has a natural gas line at the install point before buying.

Can I install it myself?

Gas connections and venting are best left to a licensed installer. The unit is compact and simple to hang, but the gas and exhaust work carry real safety risk.

How does it compare with a tank heater?

It saves space and avoids standby heat loss, but its output is lower than a typical tank. For one fixture it works well; for heavy simultaneous demand a tank or a larger tankless unit is the better fit.