Is Water from a Tankless Hot Water Heater Hot Enough?

I would like to put in a tankless hot water heater, but I’m concerned that the water will not get hot enough. Is that a problem?” -Gail

Hi Gail,

Tankless water heaters can get the water plenty hot enough. Depending on the brand and model, most tankless water heaters have a temperature setting that is adjustable between 100° to 140° (most tank water heaters are set around 120°).

In order to make sure the water will be hot enough, it’s important that a tankless water heater is sized based on your climate and hot water needs.

  • Size tankless water heater for usage: The amount of water being used can affect the temperature of the hot water if the unit is too small for the amount of flow it’s being asked to produce. A unit that is too small for the amount of hot water it is asked to provide may work fine when only one shower is running, but the temperature could drop when another hot water tap is opened at the same time.
  • Size tankless water heater to the water supply temperature: Tankless water heaters are rated based on the rise in water temperature they produce. The colder the temperature of the water supply coming in, the lower the maximum temperature of the heater. So if you live in a cold climate, like Alaska, you’ll need a larger tankless water heater than someone living in a warm climate, like Florida.

Good luck with your project,



  1. I moved to Florida in 2012 to a house that has a tankless water heater. I did not seem to be getting hot water, so I had the heater worked on to the tune of $288. I still get barely enough hot water for a 4-minute shower, and I have never been able to use the jacuzzi tub, because there is definitely not enough hot water produced to even make it luke warm! I am the only one in the house. Is this normal for a tankless water system, or is this one just faulty. Has anyone actually done a cost savings analysis of how much electricity is saved when using a tankless vs a “tank” water heater? Also, I pay for my water, and one wastes water when waiting for it to warm up. I would like to keep my utility bills as low as possible, but, then I would also sure like to use that jacuzzi tub once in a while! Please help.

  2. I had a tankless water heater for many years with no difficulty at all. I use to bath and use the laundry and someone would be in the kitchen washing dishes. I believe that the one you had was too small. When I looked into it I explained to the service person what my needs were. We had a big one. It was large enough for us and we had no difficulties ever! Yours sounds too small. Ours was LP gas.

  3. I agree with Muffin. I I stalled a 50 gal water heater tank. Filling my Jacuzzi walk in tub, half way it’s freezing cold. Then I don’t have hit water to rinse in a quick shower. Can a heat circulator be added to the water tank? I just want to soasoak.


Please enter your comment!
Please enter your name here