How to Size a Tankless Water Heater?

An important characteristic of a tankless boiler is its power – the size of a water heater. This indicator is considered to be decisive in terms of whether the selected model can provide you with the necessary amount of hot water.

The selection of the optimal water heater size is extremely important since both a too small and too large sizes threaten with negative consequences. Why? Because, if the power is insufficient, then when you turn on, for example, two taps and a shower at the same time, the heating device will not be able to maintain the required temperature and someone will be poured up with ice water, and the force of the water flow will also not please you.

If the tankless water heater size is too large, it will consume more electricity/gas and, accordingly, your bills for light/gas will increase significantly. The device will work in vain since its power will significantly exceed your needs for hot water.

So, how do you determine the ideal size for a heater without a tank? For those who are interested in this, there are a number of practical and simple tips. But, finding a contractor always remains the best solution.

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How to Choose a Suitable Tankless Water Heater Size?

In order to fully and comprehensively deal with this issue, you should know the following key concepts:

• The flow rate of water for various devices (for example, a faucet in the bathroom, shower, washing machine, etc.). It is measured in gallons per minute – GPM;
• The total flow rate of water during peak hours of use of hot fluids;
• Groundwater temperature in the region in which you reside.

Knowing these notions, you can easily assess your needs for hot water and choose the right hot water heater size. If you value your resources and you have no free time to deal with issues of this kind – finding a contractor is what will help you with dignity to get out of this situation.

So, to determine the water flow rate for different devices, you should use a special table where all the necessary values ​​are indicated. Here are some of them:

• Shower – 1.5 GPM for low flow to 3.0 GPM for standard one;
• Kitchen faucet – 2 to 3 GPM;
• Bathroom sink – 0.5 to 1 GPM;
• Dishwasher – 1.5 to 3 GPM;
• Washing machine – 2 to 3 GPM;
• Bathtub – 4 to 6 GPM.

Knowing the approximate water flow rate of one or another device, you can proceed to the next step. That is you need to determine what time of day and exactly the hour is the busiest in terms of using hot liquid. Namely, one must calculate which devices are turned on and how many of them work simultaneously. Further, having added all these values ​​together, having previously consulted the table, you will know your average GPM. Standard water heater size is indicated on the appliance.

This indicator must be stated in the technical specifications of each tankless boiler; looking for information on the manufacturer’s website, you can choose the appropriate size of the water heater.

Groundwater Temperature

But that is not all. The last but not least important indicator in determining the optimal dimensions of a boiler without a tank is the temperature of the groundwater in your area. It is generally accepted that the average temperature of the liquid to which the water in the house is heated is 110 degrees Fahrenheit. Why do you need this? And to that if, for example, the temperature of the groundwater in your region is 52 degrees, then your device will need to heat it at 58 degrees in order to supply water at an acceptable temperature. This affects the speed of the water flow – the colder the water, the slower it heats up, more gas/light is used to complete the task, and, accordingly, the overall GPM decreases. All of this should be taken into account. For those who do not want to bother with tables and maps of groundwater temperature – there is a way out – finding a contractor.

If you still intend to deal with this matter yourself, you should know that the Internet is full of resources that can help you. One of those is the online calculators GPM and even calculating the temperature of the water at the outlet. You only need to insert the corresponding values in the specified fields and get the finished result. Then, look for a water heater size you require.

Finding a contractor will greatly simplify your life and eliminate the need to engage in further manipulations with a tankless boiler. After all, someone must correctly install and connect it to start to function. Do not forget about it and choose the best option for yourself.