A tankless water heater is a product that provides hot water according to the requirements and needs of people. There are many buyers who get questions in their mind before buying a water heater. The question is, what size tankless water heater do I need?. Here, in this general, we will help people to select the best water heater for their homes.

What Size Tankless Water Heater Do I Need

It is really important to buy a water heater that is accurate for you according to your home and family members. If you buy a heater which is too large and you are only 3 or 4 members in a house, it definitely will not be a good decision. Similarly, buying a small water heater for a huge family is not good.

Size Overview

While considering a suitable size for buying the best water heater, you just need to focus on two things. The first is, flow rate, and the second is the temperature rise.

Electric or Gas

Gas and electric water heaters are having diverse rating inputs. Gas input is estimated in BTUs, and electrical input is estimated in watts.

At the point when we talk about gas water heaters, its rating input measurement is from 30,000 to 180,000 BTUs. It likewise relies upon the size of the water heater. The more BTUs, the quicker the unit will warm water.

Electric or Gas

On the counter side, discussing electric heaters its capacity input is around 1,440 to 5,500 watts. The higher the wattage, the more rapidly The unit will warm water.

So, it truly depends on the availability of gas and electricity. In some areas, people do not have natural gas. In such areas, people do not have any other option and they will use an electric heater. In the case of having both gas and electricity available in your area, choose a heater according to your requirement and gas pressure.

Energy Factor

Considering the energy factor is also important. When you’re using a small heater whether it works on gas or electricity., it will consume less energy. Energy factor is a formula that works with the idea of the energy that is converted into water heaters, and the total amount of energy that is used during the use of a water heater.

Flow Rate

The flow rate of a water heater is always measured by GPM, which means gallons you can fill in a minute. Flow rate all depends on the water you need at a time. The amount of water you use in a day depends on the area of your house and also on the members of your house. With this calculation of using water, you can easily select a water heater according to your needs.

Flow Rate

One thing that is important here is that you should know about the usage of water during peak hours. Like, in the morning everyone needs hot water, and morning time can be called peak time for using water.

We cannot get accurate data of using water, it always varies on people and their way of using water. Some people use a little water while taking bath, but on the other hand, there are also people who use a lot of water while taking bath. So, we can have an estimate but not an accurate measurement.

 Here is also a formula for the flow rate of water. 

Flow rate = 60 / Seconds required to fill a bucket

Here is an example chart with which you can figure out your usage of water per day.

PRODUCT NameFiltration StagesWater ProductionWaste RatioPrice
Hydro-logic RO 310353 stages100 Gallons2:1
Hydro-Logic 310233 stages1000 Gallons2:1
Aquatic life 3-stage RO3 stages100 Gallons1:4
Aquatic life 4-stage RO4 stages75 Gallons2:1

The quicker flow rate or cooler temperatures can here and there lessen the water temperature. So, here we can say how much water you need is the flow rate.

Temperature Rise

Temperature rise implies the contrast between the approaching cold water temperature and the temperature you need at the required time. 

it’s all about the temperature that grounded water already has, and when with the help of a water heater it will convert into desired hot water. After the process of whether the water we will get would be called hot water and this process is known as temperature rise.

Temperature Rise

It also depends on the climate in which you are living. If you are living in an area where most of the time the climate is cold, you would need to have a high temperature to get your desired hot water. On the contrary, living in an area where the climate is normal you will need less hot water and the temperature rise will also be decreased.

 Here is the formula of temperature rise. 

Required temp rise = Output water temp – Feed water temp

It can be measured with a thermometer, but an easy way is to calculate it with the temperature of grounded water.

Water heater selection:

Now, you can select a perfect heater after having the estimated calculation of flow rate and temperature rise. After that get the average usage of water at peak hours and buy a water heater that meets your desired requirements.

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