However, although gas-fired tankless water heaters tend to have higher flow rates than electric ones, they can waste energy if they have a constantly burning pilot light. If you purchase a model that uses a standing pilot light, you can always turn it off when it’s not in use to save energy.Click to see full answer. Accordingly, what is the downside of a tankless water heater?Tankless water heaters produce an endless supply of hot water, take up less space, have a lower risk of leaking, are safer, and have a significantly longer lifespan on average. The main disadvantage of tankless water heaters is their upfront cost (unit and installation) is significantly higher than tank-style heaters.Furthermore, what are the advantages and disadvantages of a tankless water heater? Advantages and Disadvantages They can virtually eliminate standby losses – energy wasted when hot water cools down in long pipe runs or while it’s sitting in the storage tank. By providing hot water immediately where it’s used, tankless water heaters waste less water. Hereof, do tankless water heaters require water softeners? All tankless water heaters, and even traditional water heaters, should have a sediment filter installed to filter the incoming water. Keep in mind that without a water softener regular maintenance and flushing can keep your tankless running efficiently.What size tankless water heater do I need for a family of 5?Like, a hot water tank for 5 people will require at least a 60-gallon tank. Since tankless water heaters supply endless hot water, you don’t have to worry about capacity, but instead, think in terms of water flow rate. Gallons Per Minute (GPM) is the key when it comes to sizing tankless water heaters.