Best Tankless Water Heaters for Whole House


Why Whole House Tankless Water Heaters

Buying a tankless water heater for whole house installation can be tricky. It’s not a ‘one unit fits all’ concept. You would think that a unit labeled as whole house will be good for any house but it doesn’t work that way. Whole house units have higher GPM (gallons per minute) or flow rate and they can supply water for more than one fixture at a time. For example, a unit can handle two shower fixtures at a time, as well as a dishwasher and a sink hot water faucet.

But it’s not that simple. Different fixtures use different amounts of water. Some shower heads could use up six times more water than ordinary shower heads. So the type of whole house tankless water heater you need would depend largely on the number of fixtures you have and if you expect them to be running simultaneously. Sometimes, you would need more than one whole house unit installed in your house to meet your hot water demands. So how do you choose which whole house tankless water heater is right for your home?

Best Tankless Water Heaters for Whole House Comparison Table 2017

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How to Choose the Best Tankless Water Heater for Whole House

Before we look at the different factors that you need to consider in buying a whole house tankless water heater, you would be glad to know that you can install a combination of tankless water heater types to meet the demands of your home.

For example, you can put a separate POU (point of use) unit for smaller fixtures, like in the kitchen and then install the whole house units specifically for the main baths. It’s a matter of strategy and it will also help you save on water and energy costs. For best results, you can consult with a professional electrician and plumber to help you strategically install your heaters that are best for the size of your home and floor plan.

Here are some of the important things to consider before buying a whole house’s tankless water heater:

  • Gas or Electric

    The first thing you need to decide on is whether you want an electric or a gas powered tankless water heater. Whole house tankless units are available in both. Electric units are a lot less expensive than gas-powered ones; I’d say almost half the price, but gas units are more powerful.

    If you’re replacing an old gas powered storage tank heater, of course, it might be more practical to just use a gas tankless heater. Same with electric. If it’s a new installation, you have more leeway.

    To have a better idea about electric tankless water heaters, you can check our guide, the Best Electric Tankless Water Heaters. If you’ve decided to go with a gas type unit, you then have to choose between natural gas and propane.

    To learn more about these two gas-fired machines, you can read our guides, the Best Natural Gas Tankless Water Heaters and Best Propane Tankless Water Heaters. Compare their benefits, prices, and which one is most suitable for your home and location.

  • Gallons Per Minute

    Whole house units generally have more GPM capacity or flow rate. If you have a lot of showers, you would need one with more GPM. 8-9 GPM may be sufficient for mid to large houses.

    Some have less capacity but are still considered whole house because they can supply water to multiple fixtures simultaneously, like the Eemax EX190TC 3-Gallon Series Two Whole House Electric Tankless Water Heater. This is good for smaller homes and is a more practical choice rather than installing three POU units.

  • Temperature Control

    It would be very useful to have this feature so you can control how hot the water gets especially since it is going to be used in multiple areas of the house. If you can control the temperature for each room, that would be even better.

  • Advanced Controls

    Some units offer special controls intended to address issues concerning whole house applications. The Stiebel Eltron Tempra 24 Plus Electric Tankless Whole House Water Heater, 240 V, 24 feature Flow Control which ensures constant temperature output no matter how great the hot water demand is. It automatically adjusts the flow of water in multiple fixtures to avoid temperature fluctuations.

  • Durability

    A whole house unit needs to be built for heavy-duty use. Check how durable the parts are and the type of warranty that comes with.


Everything you need to consider in buying a tankless water heater is discussed carefully in the three guides that we mentioned earlier. The factors stated above are just additional guidelines to help you in comparing whole house units. Make sure to check the requirements and restrictions in both gas powered and electric units.

Further Reading on Tankless Water Heaters