Buyer's Guide

How should a tankless water heater be sized for hydronic floor heating?

Do you intend to install a tankless water heater as the heat source for your hydronic floor heating? I know that when you decided to go with a tankless water heater, many warning signs began to appear. So, in order to save time, we’ll go through the issue in detail.
We’ve outlined some steps you can take to address your sizing concerns. Furthermore, the initial positive aspects are described. All you have to do is sit down and stay informed in order to make the best choice for yourself.

How should a tankless water heater be sized?

The size of the tankless water heater is responsible for providing reliable service when needed. The combination of temperature rise and flow rate requirement has a significant impact on tankless water heater size selection. I’ve gone a step further and prepared a step-by-step guide for you to have the greatest tankless water heater when you need it.

Step 1: Calculate the amount of hot water required.

You must be quite familiar with your hot water needs. When it comes to peak demand, every residence follows a systematic pattern. You can ask the family about it and figure out when they need the most help from hot water. Standard shower flow can be increased to 2 GPM, while the dishwasher and washing machine share the same top.

With a basic flow rate of 1.5 gallons per minute, the kitchen sink and others work nicely. If everything is covered, you can estimate that it can request up to 6GPM in two showers and others. The progressive increase in hot water demand for four showers and others will be close to 10 GPM.

Step 2: Determine the Temperature Rise

The water entering from the source has its own temperature control. Assume your hot water shower’s temperature is 110 degrees Fahrenheit. Groundwater in frigid locations is about 55 degrees.

After adjusting the estimates, a temperature rise of 55 degrees is required. The whole report is essentially identical to the chilly region, although in warmer regions, you may need to continue with lower estimates as temperatures rise.

To determine the best tankless hot water system for your needs, consult product reviews or other online size guides. Always opt for a larger tankless water heater to save money in the long term.


How to properly size a tankless water heater for hydronic floor heating

Are you considering installing a radiant hydronic floor heating system in your home? In that case, proper tankless water heater sizing is critical. The advantages are numerous, but if you do not perform the necessary systematic work, you may find yourself on the receiving end.

Analysis of heat loss

The initial step in the process is to calculate the temperature of the room with an hourly change rate. To determine the proper volume, measure the length, breadth, and height of the room hourly change rate. To determine the proper volume, measure the length, breadth, and height of the room. After that, you may use the Stefan-Boltzmann equation of radiation to calculate the exact heat loss on your hydronic floor heating system.

Source of heat

You appeared to be on your way to the water heating source. However, selecting the best tankless water heater is equally critical. Even after subtracting heat loss, they should generate enough heat to meet your requirements. When you have a professional on your side, you have a lot more options.

These few items can easily be combined to provide you with a greater floor heating function. Airtight sealing is also required for efficient water heater turnover. If you are new to the timeframe, it is best to seek professional assistance.

Do you require the assistance of a professional to size a tankless water heater for hydronic floor heating?

Setting up a hydronic heating system at a desk is not a simple task. You must perform the heat loss analysis, which I believe most of you can readily do. However, the second half of the work will be more difficult than the first.

You must construct the plastic pipeline beneath the floor bed in a tightly packed batch. Connecting the heat source to the main stoppage is also difficult if you are unfamiliar with the installation process.

If you are completely new to the work, you will undoubtedly require the services of an expert. Even if you have basic knowledge of hydronic floor heating installation, I recommend that you consult a professional. It may appear pricey in the short term, but it will be the opposite in the long run.

The benefits of using a tankless water heater for hydronic floor heating

There are numerous advantages to using a tankless water heater for hydronic floor heating. Some worthy terms are listed here.

  1. They are environmentally friendly because they do not use fossil fuels for heating.
  2. The promise of continuous hot water delivery with minimal energy loss It is capable of conserving energy because the mechanism only activates when you request hot water.
  3. Condensing technology is used, which is more efficient than most other non-condensing technologies.
  4. It has a life expectancy of roughly 20 years, which is longer than most other heaters on the market.
  5. Its tiny design allows it to be placed almost anywhere.


When it comes to hydronic floor heating, there are primarily two possibilities: Historically, water heating has outperformed electric heating. You simply need to complete the sizing correctly to have the finest function at the best price.

We are here to help consumers learn more about their household products. Our goal is to stay honest with your visitors and provide them with the best information possible. Stay on the border with us and keep the door open for additional information.


Md Belal Uddin

I am an experienced product reviewer with a passion for sharing my knowledge and insights about various products. With a keen eye for detail and a dedication to providing honest and unbiased reviews, I strive to help consumers make informed purchasing decisions. I believe in the power of research and firsthand experience to provide valuable information to readers.

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