10 Best Water Heaters for Radiant Floor Heat & Other Applications (2022)

10 Best Water Heaters for Radiant Floor Heat & Other Applications (1)

The best water heater for radiant floor heat is a more energy-efficient, safer, more comfortable, and healthier solution than the conventional boiler and forced-air HVAC systems. It does not demand too much space for installation, and it ensures consistent and uniform space heating for the modern family.

Deciding which water heater to buy for radiant floor heating applications requires an understanding of several factors. These parameters can help prospective buyers decide what they need to look for in the ideal product.

Our search for the top-rated water heater for space heating purposes allowed us to identify three crucial factors.

  • Heating Performance: A hydronic heater must make any living space more comfortable to stay in by delivering the right amount of heat into the room. A water heater’s BTU or wattage rating reflects its heating performance. Hence, a product with a higher wattage or BTU rating is better than one with a lower rating.
  • Energy Factor: Like any other device, water heaters have different energy efficiency ratings. In general, electric hydronic heaters (EF ratings between 0.75 and 0.95) are more energy-efficient than gas-powered heaters (EF ratings between 0.5 and 0.7). One must always get a water heater with a higher EF rating.
  • Energy Source: Although gas-powered water heaters are less energy-efficient than electric water heaters, they are more economical to operate because gas is more affordable than electricity.

Other factors can impact a water heater’s floor and wall heating performance. We will point out these other parameters in the succeeding product reviews and the comprehensive buying guide that follows.

Table of Contents

  • Top 10 Water Heater for Radiant Floor Heat Reviews
    • 1. Stiebel Eltron Tempra 15 Plus Electric Water Heater
    • 2. Rheem RTE 13 Electric Tankless Water Heater
    • 3. EcoSmart ECO 18 Electric Tankless Water Heater
    • 4. Takagi T-H3-DV-N Condensing Tankless Water Heater
    • 5. Stiebel Eltron Tempra 20 Plus Tankless Water Heater
    • 6. EcoSmart ECO 8 Electric Tankless Water Heater
    • 7. Marey GA10LP Power Propane Gas Tankless Water Heater
    • 8. Rheem RTEX-18 Electric Tankless Water Heater
    • 9. Rinnai RU199iN Condensing Tankless Water Heater
    • 10. Takagi T-H3M-DV-N Condensing Direct Vent Tankless Water Heater
  • What to Look for When Buying Water Heaters for Radiant Floor Heat
  • Is Radiant Floor Heating More Efficient
  • What Type of Water Heater Do You Need for Radiant Heat
  • How Big of a Water Heater Do I Need for Radiant Heat
  • How Hot Should Radiant Floor Heat Be
  • Conclusion

Top 10 Water Heater for Radiant Floor Heat Reviews

1. Stiebel Eltron Tempra 15 Plus Electric Water Heater

10 Best Water Heaters for Radiant Floor Heat & Other Applications (2)

I consider the Stiebel Eltron Tempra 15 Plus the top-tier electric water heater for radiant floor heat and other applications. This hydronic heater has exceptional energy efficiency and superb heating capability.

I love this tankless water heater’s 14,400-watt power capacity, making it ideal for heating living spaces as large as 1,400 square feet. As long as this radiant heating system works underneath floors or inside the walls, a family of five will never have issues with cold surfaces again.

The electric tankless water heater also has one of the highest UEF ratings on the market – 0.99. People will never worry about its 14.4-kW capacity because the water heater has intelligent self-modulating technology. The automatic modulator monitors the water heater’s electrical requirements. It ensures the device uses the least amount of electricity for heating the water.

I also like its advanced flow control mechanism, ensuring the household receives all the hot water it needs anytime. One will never worry about heating the floor or walls when a family member is showering, washing the dishes, or doing the laundry. The in floor heating water heater guarantees a sufficient water flow of 3.1 gallons per minute (GPM).

Its size and design are also unbelievable. This electric tankless water heater looks like a sturdy briefcase, measuring only 19.5 inches tall, 21.5 inches wide, and 8.5 inches deep. Its steel casing can also withstand earthquakes.

Unfortunately, this is already a discontinued product. One can still find retailers selling it, though. This electric tankless water heater also requires two 40-amp circuit breakers to accommodate its 60-amp draw. Hence, it would be best to call a professional to install this water heater.

Pros

  • 4-kilowatt heating performance
  • 99 Energy Factor rating for higher efficiency and 3.1 GPM flow rate
  • Intelligent self-modulating technology for better savings
  • Advanced flow control for uninterrupted water supply
  • Seismic-proof and compact construction

Cons

  • A discontinued model
  • Requires professional setup

Regardless, the water heater’s intelligent design and efficiency make it the best device to heat the floor. It is German technology at its finest.

2. Rheem RTE 13 Electric Tankless Water Heater

10 Best Water Heaters for Radiant Floor Heat & Other Applications (3)

I can understand why many people have Rheem water heaters in their homes. After all, it is one of the most trusted brands worldwide. The company’s RTE 13 electric tankless for radiant heat is also one of the best in the market, with its high energy efficiency, self-modulating technology, and high-power heating capability.

This water heater for radiant floor heating packs 13,000 watts of power, capable of warming a living space as large as 1,300 square feet. Family reunions and other social gatherings will never be chilly because this water heater supplies the in-floor tubing network with up to 4.0 GPM of hot water.

Although it does not have the Tempra 15 Plus’s 0.99 Energy Factor rating, I still commend this product’s 0.95 EF score. The heat it generates goes straight to the water with minimal loss.

Moreover, hefty electric bills are never a concern because of its self-modulating technology. The system only draws enough electricity to produce the best results.

The RTE 13’s form factor blew me away. The water heater only measures 10 inches tall, 7.25 inches wide, and 3.63 inches deep. For a device this compact, I find its 13-kW capacity astonishing.

The compact design also lends itself to DIY installation. At least, people no longer have to worry about paying a few hundred dollars for a professional to set up this system in their homes.

Unfortunately, the company recommends expert installation to avail of its 10-year warranty. Setting it up as a DIY project might not be a good idea if repairs are needed. Additionally, its price is higher than other hydronic radiant floor heating systems.

Pros

  • Self-modulating system for energy savings
  • 95 Energy Star certification for energy efficiency
  • Ultra-compact design for effortless installation
  • 10-year warranty

Cons

  • Professional installation recommended for warranty purposes
  • Priced higher than other brands

Still, I trust Rheem as much as I do my BMW. If the company says its water heater is perfect for heating floors, walls, and living spaces, so be it.

3. EcoSmart ECO 18 Electric Tankless Water Heater

10 Best Water Heaters for Radiant Floor Heat & Other Applications (4)

Many families consider the EcoSmart ECO 18 the top-rated tankless water heater for radiant floor heat because of its high efficiency and heating capabilities. Not only does it ensure more efficient space heating, this device can also be installed in DIY style without voiding its warranty.

Inside this super-compact water heater is a heating component that delivers 18,000 watts of power, heating the water in seconds. It is the perfect solution for people who want a small-footprint device that looks like a medicine cabinet on the wall.

I am not only surprised with this water heater’s 18-kW rating. Its 0.998 Energy Factor rating is also astounding. Its energy efficiency translates to almost-negligible heat losses, ensuring families get the warmth they deserve in their 1,800-square foot room.

This water heater for radiant heating also has a self-modulating technology that guarantees additional savings of up to 60%. The technology ensures efficient water heating with minimal electric consumption.

(Video) Can you Heat your Shop with a $200 Water Heater? Radiant Floor Heating For My Shop | Allison Customs

One might assume this electric tankless water heater for radiant heat comes with a hefty price tag. It does not, costing only about half the price of the RTE 13. It also comes with a lifetime warranty, unlike the 10-year period other brands offer. One can say this water heater delivers exceptional value.

Sadly, some people might dislike the product’s ‘Made in China’ labeling. However, I can guarantee it is an American brand with a manufacturing facility in China (think Apple and other well-known US brands).

Additionally, the system’s electrical requirements can be an issue for some people. This product requires a 150A service and two 40-amp DP breakers.

Pros

  • 18,000-watt heating performance and a small footprint
  • 998 UEF for optimum water heating
  • Self-modulating technology for up to 60% cost savings
  • Great value for its power and features
  • Lifetime warranty, DIY installation possible

Nevertheless, this hot water heater is one of the best products in the market. Its exceptional value, remarkable heating capacity, and power efficiency make it a worthy item to have in the home.

4. Takagi T-H3-DV-N Condensing Tankless Water Heater

10 Best Water Heaters for Radiant Floor Heat & Other Applications (5)

Families who prefer a gas-powered hot water heater for infloor heat should consider the Takagi T-H3-DV-N. This high-efficiency gas water heater with condensing-modulating technology is as efficient as electric water heaters in ensuring comfortable living spaces.

I love this gas hydronic heater’s 199,000 BTU rating, capable of heating large rooms from 5,000 to 7,900 square feet. That is why many space heating experts also recommend this product to small commercial establishments. I can only imagine how warm a room will be with this product heating the space.

Many gas-powered hot water radiant floor heating systems have an efficiency rating of less than 70%. This water heater comes with a surprisingly high EF rating of 0.93 or 93%. Its heat loss is sufficiently low, making it almost comparable to high-end electric water heaters.

At its core is a commercial-grade copper alloy heat exchanger. It is 25 times more effective in transferring heat than typical stainless steel components. Delivering up to 10 gallons of hot water per minute is a cinch with this water heater, so I always have adequate space heating.

One issue that scares people from gas water heaters is nitrogen oxide formation. Families will never worry about this phenomenon with this water heater because of its outstanding engineering. It produces NOx gases but at ultra-low levels.

Unfortunately, I find its price exceptionally prohibitive, costing about two times the RTE 13’s price. This radiant floor heating system is also bulkier than other products, with physical dimensions of 11.25 inches by 24.88 inches by 17.75 inches.

Pros

  • High 199K BTU heating capacity
  • 93 UEF rating for better efficiency
  • Ultra-low nitrogen oxide emission
  • Commercial-grade copper alloy heat exchanger for 25x better heat transfer
  • A high water flow rate of 10 GPM

Cons

  • Bulkier than other water heaters
  • Expensive price

I still recommend this Takagi tankless water heater for radiant floor heating purposes despite the price concerns. It is an excellent choice for large houses and small commercial establishments due to its energy efficiency and water flow rate.

5. Stiebel Eltron Tempra 20 Plus Tankless Water Heater

10 Best Water Heaters for Radiant Floor Heat & Other Applications (6)

I love German technology and craftsmanship, and the Stiebel Eltron Tempra 20 Plus is one of the reasons why. This tankless water heater for infloor heating has a terrific heating performance, at about the same price as US brands.

I appreciate this hydronic heater’s 19,200-watt heating capability, providing warmth to a large room full of people. Although it delivers 19.2-kilowatts of water-heating energy, it only requires 80 amperes of residential electricity to run. Like all Tempra Plus Series water heaters, this product features an intelligent self-modulating technology that guarantees energy savings.

I also like its 0.99 EUF rating, minimizing heat loss while ensuring optimum space heating. I commend German engineers for using solid copper instead of stainless steel because the material guarantees faster and more efficient heat transfer. Its advanced water flow system gives this water heater exceptional water-optimization capabilities, delivering a sufficient hot water supply.

This tankless water heater for radiant heat floor application also comes with cutting-edge technology for effortless control. I love its clear digital display and easy-to-use control knob, including the preset temperature buttons and a real-time water flow and energy savings monitor. Children can operate this device without a fuss.

My only concern is its three-year warranty on parts, although the company offers a seven-year assurance against leaks. I believe a ten-year guarantee would have made this product more appealing. I do not recommend this product for DIY installation because it requires a dedicated circuit breaker to accommodate its power requirements.

Pros

  • 2-kW heating performance and 80A energy requirement
  • 99 UEF rating for high-efficiency space heating
  • Superior modulating and water-optimization technologies
  • Solid copper element for ultra-fast heating
  • Effortless to control and manage with buttons and monitor

Cons

(Video) Radiant Floor Heat With A Water Heater

  • Only three-year warranty on parts
  • Needs circuit breakers, which users might have trouble setting up

Still, it remains one of the most exciting hydronic heating systems on the market, delivering instant hot water every time, anytime. It has a solid construction, an astonishing heating capacity, and an excellent energy efficiency rating.

6. EcoSmart ECO 8 Electric Tankless Water Heater

10 Best Water Heaters for Radiant Floor Heat & Other Applications (7)

I love EcoSmart products, despite some of them having a ‘Made in China’ label. I do not think it matters anymore, considering many American companies have overseas manufacturing facilities.

Small families with modest-sized living spaces should consider the EcoSmart ECO 8 electric water heater for radiant heat. This model has a tankless design and a powerful, 8,000-watt element to raise the cold water temperature to a comfortable 140 degrees Fahrenheit. It is perfect for floor heating, making icy and numb feet a thing of the past.

Although made in China, this product comes with a UEF rating of 0.998 – higher than many brands. Contributing to its exceptional energy efficiency is an advanced self-modulating technology and a solid heat exchanger. One can enjoy up to 50% savings using this water heater to warm floors and walls.

I am blown away by this hydronic floor heater’s compact form, measuring 11.5 inches tall, 8 inches wide, and 3.7 inches deep. It makes me wonder how a tiny device can deliver outstanding floor heating performance.

I looked at this tankless water heater radiant heat diagram and found that its installation and maintenance are a breeze. Although the components are as tough as rock, one can effortlessly replace them should they show signs of damage or wear.

As mentioned, this hydronic floor heating system has a ‘made in China’ label. Hence, people who are unenthusiastic about Chinese-manufactured items might want to consider something else. A more crucial downside is the device’s 0.8 to 2.0 GPM flow rate, which could be insufficient for some households.

Pros

  • 8,000-watt heating capacity for small to medium-sized rooms
  • 998 UEF for efficiency & 140℉ water temperature
  • Advanced self-modulating system for 50% energy savings
  • Super-compact design for effortless installation
  • Durable with replaceable components

Cons

  • Only 0.8 to 2.0 GPM flow rate
  • China-made

Regardless, for a couple of hundred dollars, one can already bring home this efficient device for heating floors, walls, and living spaces. Its super-sleek design and lightweight characteristic allow effortless installation. This tankless system offers unbeatable value, in my opinion.

7. Marey GA10LP Power Propane Gas Tankless Water Heater

10 Best Water Heaters for Radiant Floor Heat & Other Applications (8)

Some families prefer using propane gas instead of electricity or natural gas for heating. In that case, the Marey GA10LP propane boiler for radiant floor heat is an excellent choice. This water heater has effortless installation and an impeccable water heating performance no modern propane-using household will want to miss.

This water heater delivers 79,228 BTUs to warm a 1,600 to 3,100-square-foot living space, perfect for most small to medium-sized families. Meeting relatives for a fantastic dinner is more enjoyable with this device heating the water tubing network under the floor or inside walls. It creates a warm and toasty environment for everyone.

Its ingenious design gives families up to 60% savings from their electric bills. There is no fretting about a kilowatt increase in energy consumption because this water heater uses a battery to ignite its pilot light. Using a water heater for radiant heat has never been this economical. It also delivers a maximum of 3.1 GPM, sufficient to circulate hot water throughout the in-floor tubing network.

This propane water heater’s design is terrific, as well. It is lightweight at only 21 pounds, ensuring homeowners will not have issues with its installation.

I also appreciate its price tag, which is about 80% lower than the leading gas water heater brand. It is an excellent choice for families with tight budgets.

However, controlling the temperature settings is hit-or-miss. I read customer experiences highlighting its all-or-none design. Some people might also think lowly of its ‘Made in China’ label. However, I must say this company is an American brand with an international presence.

Pros

  • 79,228 BTU heating capacity for small to medium-sized rooms
  • 1 GPM maximum flow rate
  • Up to 60% energy savings; with battery-powered pilot light
  • Lightweight design for installation ease
  • More affordable than other gas water heater brands

Cons

  • Not effortless to control the water temperature levels
  • Made in China

Overall, I still recommend this water heater for people who want to use propane gas to heat their living spaces. It is affordable and works fine.

8. Rheem RTEX-18 Electric Tankless Water Heater

10 Best Water Heaters for Radiant Floor Heat & Other Applications (9)

The Rheem RTEX-18 is an efficient and effective tankless water heater for radiant floor heating and other applications. It comes from a reputable company, giving confidence to buyers about its quality craftsmanship, performance, and overall value.

I like this hydronic heater’s 18-kW copper heat exchanger that raises the water to the desired temperature within seconds. Warming a room is never a waiting game. Family members can enjoy a warm and cozy environment immediately once they flip the switch.

This electric water heater for radiant floor heat has a 0.99 energy efficiency rating, which I find commendable because most products on the market offer less. The level of heat loss is negligible, ensuring the household gets a comfortable living space to enjoy the company of friends, guests, and visitors.

An essential aspect of this electric water heater is its intelligent self-modulation, ensuring easy temperature control and exceptional energy savings. One can install this in high-pressure water systems with 150 PSI. There are also no issues with its flow rate because the water heater can deliver a maximum of 4.4 gallons of hot water per minute.

This hot water heater for radiant floor heat comes with the company’s limited five-year warranty for the heating chamber and one year for parts. Unfortunately, one must hire a licensed plumber to install the unit to ensure its validity. I also noticed temperature fluctuations in the first few weeks of operation, which subside with continuous use.

Pros

  • 18,000-watt water heating performance with copper heat element
  • 99 Energy Star certification for minimal heat loss
  • Intelligent self-modulation
  • 150 PSI maximum pressure
  • 4 GPM maximum flow rate
(Video) Will a Tankless Water Heater Work for Radiant Floor Heat? Pros & Cons

Cons

  • Expert installation recommended for warranty purposes
  • Unstable temperature in the first few weeks

To say I like this water heater for radiant floor heating is an understatement. I adore it. It is more affordable than the Rheem RTE 13 and packs great heating performance, too. The device handles high-pressure water systems and delivers an exceptional hot water supply to heat living spaces.

9. Rinnai RU199iN Condensing Tankless Water Heater

10 Best Water Heaters for Radiant Floor Heat & Other Applications (10)

Families with large living spaces can trust the Rinnai RU199iN tankless water heater for radiant heating. It has one of the highest BTU ratings among residential gas-powered water heaters and an admirable water flow rate the competition can only dream of having.

With its 199,000-BTU rating, this water heater can warm living spaces as large as 4,000 to 8,000 square feet while also providing hot showers to three people. Never again will families complain of refrigerator-like rooms or ice-cold bath times. This water heating appliance can make life more comfortable for everyone.

Although this gas tankless heater only has an EF score of 0.96, it is still 26 points above the industry average. I must reiterate that gas water heaters typically have an energy efficiency of 0.50 to 0.70, making this appliance a cut above the rest.

I also commend its maximum water flow rate as people can shower simultaneously and heat their floors. Eleven gallons of hot water every minute is several gallons higher than what other brands offer.

I also like its Circ-Logic technology, ensuring an ultra-fast water heating process. This product raises the water temperature within two minutes, making it stand out among gas-powered tankless heaters.

I commend the company for integrating an optional WiFi module into this water heater. I can be in my living room watching my favorite TV show, and I can easily control the appliance’s different settings.

Unfortunately, the device’s heating power and intelligent technology translate into a heftier price tag than other gas water heaters. Moreover, one cannot install this outdoors.

Pros

  • 199,000 BTU heating performance
  • 96 EF rating for efficiency
  • 11 GPM maximum water flow rate
  • Advanced Circ-Logic technology for ultra-fast heating
  • Optional Smart WiFi connectivity for convenient management

Cons

  • Not budget-friendly
  • Indoor use only

Regardless, I still advise homeowners with existing natural gas lines in their homes to consider this hydronic heater for radiant floor heat. It does a phenomenal space heating job without undermining one’s hot water enjoyment.

10. Takagi T-H3M-DV-N Condensing Direct Vent Tankless Water Heater

10 Best Water Heaters for Radiant Floor Heat & Other Applications (11)

The Takagi T-H3M-DV-N is a remarkable condensing tankless water heater that runs on natural gas. It is one of the most powerful hydronic heaters on the market, capable of heating large living spaces for everyone’s comfort.

I am surprised by this tankless heater’s two heat exchangers featuring commercial-grade copper alloy and stainless steel. Its heating components deliver 120,000 BTUs of energy, heating the water as quickly as one can imagine. Its heating performance is perfect for large households, eliminating annoying cold spots.

This hot water heater for radiant floor heat has a 0.90 UEF score, 20 points better than the industry average for gas-powered water heaters. Families will love the heat it generates, making rooms more pleasant for everyone.

Although it comes with a direct vent and a condensing design, this hydronic heater incorporates revolutionary technology. Households will never grow weary or anxious about nitrogen oxide emissions because this gas hydronic heater ensures NOx fumes are lower than 20 ppm.

I also appreciate this radiant floor heating hydronic heater’s maximum flow rate of 6.6 GPM. Other products can only offer half the capacity.

Sadly, I find this water heater bulkier and heftier than similar products. It is 22.87 inches tall, 10.81 inches deep, and 13.87 inches wide. It also weighs 44 pounds, making it heavier than most. It is still more manageable than tank systems, however. What annoys me the most is this water heater’s noise level during operation. It is not as quiet as other products I reviewed.

Pros

  • 120,000 BTU heating performance
  • 90 UEF rating for energy efficiency
  • Copper alloy and stainless steel heat exchanger combination
  • Less than 20 ppm ultra-low NOx emissions
  • 6 GPM maximum flow rate

Cons

  • Bulky and hefty
  • Noisy operation

Nevertheless, this gas-powered water heating appliance is perfect for homes with existing natural gas lines. One can never question its efficiency and cost-effectiveness in the long run. It quickly heats the water for everyone’s enjoyment, too.

What to Look for When Buying Water Heaters for Radiant Floor Heat

10 Best Water Heaters for Radiant Floor Heat & Other Applications (12)

(Video) The 5 Best Radiant Floor Heatings in 2019

Choosing the most suitable water heater for radiant floor heat is easy if buyers know what they should look for. Radiant floor heaters come in different types, including boilers/water heaters and resistance wire systems. Here are several things one must consider when buying the right hot water heater for radiant floor heating.

Heating Performance

The radiant floor heating water heater has a high kilowatt rating (for electric systems) or BTU rating (for gas-powered units). A hydronic floor heating system has a different sizing formula than conventional domestic hot water applications.

Adequate space heating power requires about 10 watts of electricity or 25 to 50 British Thermal Units (BTUs) per square foot of floor space. Hence, an electric hydronic heating system can be as low as 4,000 watts to as high as 20,000 watts.

On the other hand, hydronic heating systems running on natural gas or propane can produce up to 200,000 BTUs.

As a rule, one should always buy the hydronic floor heating system with the highest possible wattage or BTU rating for the budget.

Energy Factor

A hot water heater’s heat power is not the only thing buyers must look for when choosing the hydronic radiant floor heating solution. They must also consider its efficiency or the product’s ability to generate as much heat as possible without incurring significant losses.

In general, hot water heaters with a higher UEF rating are better than a product with an industry-standard rating. The electric water heater for radiant heating can have a UEF score of up to 0.95, although the industry standard is between 0.70 and 0.90.

On the other hand, a natural gas hydronic radiant floor system can have an industry-standard UEF of 0.50 to 0.70. The electric and natural gas tankless water heaters we featured here have a UEF rating of at least 0.90.

Energy Source

The hydronic radiant floor heating system’s power source also matters. An appliance that requires electricity as its power source is ideal for households without an existing natural gas pipeline. It is also perfect for families with low electric bills. An electric boiler for radiant floor heat is also less expensive than a gas unit.

Meanwhile, a gas-powered heating system is ideal if the family’s power source is natural gas or propane. The principal advantage of natural gas is its affordability, with a lower unit price than electricity.

Water Heater Type

We only included tankless water heaters in this review and guide because they deliver hot water instantly. A tankless model has powerful heating elements that raise the water temperature as it moves across the tubes. It is the perfect solution for radiant floor heating.

A tank-type radiant floor heating system can also work. However, the system stores the hot water in a compartment before distribution through the in-floor tubing network. It is how radiant floor heating works. The time it needs to heat the water makes a tank-type heater less efficient than a tankless system.

Warranty

Although not an absolute must, looking at the warranty of a radiant floor heating system gives buyers an idea of its quality and performance. No company will want to stand by its product indefinitely unless it is 100% certain about its safety, performance, and quality.

In general, a radiant floor heater with a 10-year warranty is better than one with a five-year guarantee. If buyers can get a radiant floor heater with a lifetime assurance, they know they have the best deal in town.

Is Radiant Floor Heating More Efficient

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Yes, radiant floor heating is more efficient than conventional forced-air systems by 10% to 30%. It would be best to understand that water retains heat better than air, allowing water heaters to heat the floor and living spaces longer.

Water loses only 10 degrees Fahrenheit as it moves through the PEX tubing network underneath the floor. Water heaters only need to recover this heat loss to maintain a comfortable living environment. Such an attribute also provides households with up to 30% savings in their energy bills.

What Type of Water Heater Do You Need for Radiant Heat

The water heater people need for radiant heating depends on several factors, such as space availability, heating requirements, and primary energy source.

A tankless boiler for radiant heat is perfect for households with limited space, while a tank unit is more suitable for large homes with plenty of floor space to spare. Electric units are more energy-efficient and safer than gas-powered devices, although they are costlier to operate.

Regardless of the water heater type people choose, it should provide adequate space heating through the PEX tubing network under the floor and inside walls. Hence, one must pick a water heater that delivers the right temperature for a more comfortable living space.

How Big of a Water Heater Do I Need for Radiant Heat

Sizing a hot water heater for radiant heat is not as complicated as some people want others to believe. Everything depends on what hydronic heater one uses for heating the floor and walls.

It would be best to start with an accurate room measurement. One must multiply the room’s width by its length in feet to get the floor area in square feet. For example, a room measuring 30 feet long and 20 feet wide has a floor area of 600 square feet.

Heating floors or walls requires ten watts of energy per square foot. Using the example, multiplying 10 watts by 600 square feet results in 6,000 watts or 6 kW. Hence, a 6kW electric hydronic floor heater is sufficient for this room.

If one chooses gas water heaters, one must multiply the room floor area by 25 to 35 BTUs. Hence, a 600-square-foot room will require a gas water heater with a 15,000 to 21,000-BTU rating.

Older homes with poor insulation might require 40 BTUs per square foot, needing a 24,000-BTU heater in our example. Families living in colder climates might need as many as 50 BTUs per square foot, bumping the 600-square-foot heating requirements to 30,000 BTUs.

How Hot Should Radiant Floor Heat Be

The ideal radiant floor temperature depends on the occupants’ comfort requirements, pre-existing medical conditions, developmental age, and other factors.

A boiler system pipes in scalding hot water through PEX tubing under the floor, with the temperature reaching at least 180 degrees Fahrenheit. Unfortunately, these radiant floor heating systems have condensate that can corrode pipes.

Some people might also not tolerate the high water temperature of boilers. For example, older people and young children have thinner skins than adults, making it uncomfortable for them to walk barefoot on boiler-heated floors.

On the other hand, a radiant heat water heater delivers a safer and more comfortable 130 to 140 degree Fahrenheit floor heating.

Conclusion

The best water heater for radiant floor heat makes a modern family’s life more comfortable by providing them with a warm and cozy living space minus a boiler’s complicated setup and expense. It is a safe solution for children and older persons and an efficient system for energy-conscious families.

Among the ten water heaters for radiant floor heat we reviewed, the Stiebel Eltron Tempra 15 Plus comes out on top. It is energy-efficient, provides consistent water temperature to heat the floor and walls, and features an intelligent self-modulating technology for effortless and more economical operation.

5/5 - (2 votes)

10 Best Water Heaters for Radiant Floor Heat & Other Applications (14)

Edward Manning

My work as a freelance copywriter allows me to work with Stephen later join Usawaterquality as a content producer. Our team works together to produce high-quality contents that cater to the needs of large companies and households.

FAQs

Can I use a hot water heater for radiant floor heat? ›

Use a Water Heater to Make Radiant Floor Heat Instead of a Boiler. Many people use a water heater instead of a boiler for radiant floor heat because it COSTS LESS. A hot water heater saves money when used in this way. Certainly, cost is important, but there are many other important factors as well.

Can an electric water heater be used for radiant floor heat? ›

In fact an electric hot water tank can be used to heat a house with in-floor radiant and they are thousands of dollars cheaper than boilers, and if they fail cost very little to replace; also there is very little maintenance, which can be done by the homeowner.

What is the most efficient hot water heating system? ›

Long-term efficiency: Heat pump water heaters are the most efficient alternatives to fuel, oil, and electric water heating systems. For those in the market for a water heater that is both energy-efficient and cost-efficient, heat pump water heaters show great promise.

Can tankless water heater be used for radiant floor heat? ›

These tankless systems are the perfect solution for both domestic hot water needs and radiant in-floor heating.

What size water heater do I need for in floor heating? ›

Homes with two to three people will need a 40-gallon tank, while households with four people will need a minimum of a 50-gallon capacity tank. Families with five or more people will need an 80-gallon capacity storage tank water heater.

Do you need a separate water heater for radiant heat? ›

Either a hot water heater or a boiler handles all the heated water necessary to power the radiant floor heating needs. Meanwhile, a separate hot water heater takes care of the household hot water usage. Finally, a conventional furnace might be included to heat rooms that are not using radiant floor heating.

Can I use a tankless water heater for hydronic heating? ›

With a hydronic air handler, a tankless water heater can perform two jobs, providing heat and domestic hot water to a home. Hydronic forced-air heating can also address two common concerns with electric backup heat, Goyal says: the smell and the cost.

What can go wrong with radiant floor heating? ›

9 Problems With Radiant Floor Heating: What To Watch For
  • The Cables Look Damaged.
  • The Floor Is Not Warming Up Properly.
  • Your Circulating Pump Is Not Working.
  • Your Radiant Heater's Thermostat Is Broken.
  • You Detect Leakage.
  • Damage in the Zone Valves.
  • Tripped-Out Circuit Breaker.
  • The Pipes Are Damaged and Rusty.
13 Sept 2022

What is the most reliable brand of hot water heater? ›

Best & Most Reliable Water Heater Brands in the World
  1. A.O. Smith. ...
  2. Rheem. Rheem was founded in 1925 by two brothers, Donald and Richard Rheem – and with financial backing from a third brother, William. ...
  3. Kenmore. ...
  4. Bradford White. ...
  5. American Standard. ...
  6. American Water Heaters. ...
  7. Bosch. ...
  8. EcoSmart.

How do I choose a hot water heater? ›

How to Choose a Water Heater | The Home Depot - YouTube

What is the downside of a tankless water heater? ›

In addition to high upfront costs, tankless water heaters have several other disadvantages compared to tank-style water heaters: they take longer to deliver hot water. the water temperature is inconsistent when multiple outlets are on simultaneously. they cannot provide hot water during a power outage.

Can a tankless water heater heat a whole house? ›

What is a Tankless Water Heater? These water heating systems don't utilize a tank to store heated water. They provide on-demand hot water to either a whole house, a local tap, or even an appliance.

What is the cheapest way to heat my house? ›

Gas boiler

A gas boiler is still the cheapest way to heat your home – though that's set to change soon, with the cost of gas rising more than twice as quickly as electricity.

How many gpm tankless do I need? ›

SELECTING A TANKLESS WATER HEATER

Consider how many of these needs you may have simultaneously to determine the maximum flow rate you require. For a home with 1 bathroom, we recommend 6-7 GPM; 2 bathrooms, 8 – 9 GPM; and 3+ bathrooms, 9-11 GPM.

What is the best heat source for in floor heating? ›

Solar energy is a good heat source for radiant floors because solar thermal collectors are very efficient at supplying the lower water temperatures that such systems require.

Do I need a 50 or 80 gallon water heater? ›

Water Heater Sizes

The answer to this question will vary depending on the total number of kids you have. For example, a family of 3 to 4 people should purchase a 50 – 60 gallon water heater. On the other hand, a household with 5 – 7 people may require a water heater with a 60 – 80 gallon water tank.

What size hot water tank do I need for a family of 4? ›

A small (50- to 60-gallon) storage tank is usually sufficient for one to two three people. A medium (80-gallon) storage tank works well for three to four people. A large tank is appropriate for four to six people.

How big of a boiler do I need for radiant heat? ›

Boiler Capacity

An easy rule-of-thumb for BTU requirements is to figure that you need about 50 BTU per square foot of interior space in a cold climate; 35 BTU per square foot in a moderate climate; and 20 BTU per square foot in a hot climate.

What type of boiler do I need for radiant heat? ›

The best boiler for radiant heat is generally a condensing wall hung low mass boiler. Why? Well, because radiant runs at a lower termpeature and this will allow a condensing wall hung boiler to run more efficienty than at higher temperatures.

Is hot water radiant heat efficient? ›

Energy-Efficient and Cost-Effective

Unlike gas or boiler-based systems, radiant heating systems are energy-efficient and cost-effective.

What is a hydronic water heater? ›

Hydronic heat—boilers warm your home using hot water—not air like a furnace uses—hence the term hydronic. Boilers heat but don't actually boil water, and then disperse it as either hot liquid or steam through pipes to radiators, coils, or radiant floor systems.

Can I replace my boiler with a tankless water heater? ›

Can a Tankless Water Heater replace my boiler? Absolutely! Not only can you install a Tankless ASME Boiler, but with a Combi System the same unit can be used for domestic hot water as well. Not all Tankless Units are considered boilers, so make sure to look for a unit with an ASME.

What is a closed loop hydronic heating system? ›

Hydronic heating systems are closed-loop systems, which means the water stays contained in the piping. Most systems use water, although some can use other liquids. Thermostat. The thermostat controls the system, turns it on and off, and controls the temperature.

Should I turn off radiant floor heating in summer? ›

Underfloor heating can be switched off during Summer when the outside temperature is warm enough. This is because it takes longer to warm up and cool down than other heating methods, making it harder to adjust your settings when the outside temperature is warming your home.

How long does radiant floor heating last? ›

Radiant floor heating systems do not require any maintenance. Once they are installed, they will last for 20+ years without any issues.

Do heated floors use a lot of electricity? ›

Most heated tile floors and electric floor heating systems use 12 watts per hour per square foot, meaning a 100-square-foot room would use 1200 watts in total every hour (potentially up to 300 watts less than the average space heater).

What temperature should I set my heated floor? ›

Average surface temperature is 75 - 95ºF (24 - 35ºC), but the normal comfortable range is 77 - 82ºF (25 - 28ºC). Surface temperatures can vary based on room conditions, the thermostat set point, floor covering thickness and installation method.

Why is my underfloor heating not warm enough? ›

If your electric underfloor heating isn't warm enough, you may need to adjust your thermostat settings or check the system's power output. This could also be down to the insulation in your home – check this before installation.

Can underfloor heating pipes freeze? ›

No, underfloor heating pipes cannot freeze, as once the system is up and running heat will be consistently maintained in the pipes.

What type of water heater lasts the longest? ›

Tank water heaters will last an average of 8 to 12 years, while tankless water heaters can last even longer, up to 20 years. There are also electric and gas water heaters that will vary in lifespan, but in general gas ones last 8-12 years, while an electric heater could last upwards of 10-15 years.

What are the best water heater brands? ›

Summary: The 5 Best Water Heaters of 2022 Ratings
CompanyForbes Home RatingPrice
Rheem XG50T12DU38U23.8Very good
Rheem XE50T10H45U03.8Good
Rheem XE50T12CS55U13.7Great
Rheem MHD852453.7Very good
1 more row
13 Sept 2022

Does the brand of water heater matter? ›

Even water heaters with the same brand's sticker on the front differ in quality, longevity, and warranty depending on where they are sold. For example, water heaters sold at a big box store are significantly different from those sold through a plumbing supply distributor.

Does Rheem make good water heaters? ›

Rheem is a good, mid-level water heater brand that's not too expensive. Its reputation for manufacturing durable, reliable water heaters makes it a good choice for most homes. The company sells water heater models in gas, electric, tankless, solar and hybrid styles.

How long should a hot water heater last? ›

Typically a residential hot water heater lasts between 6 and 13 years. Beyond 12 years, you are on borrowed time!

Are tankless water heaters better? ›

Tankless: Gas and electric tankless water heaters run more efficiently than the conventional water heaters of the same fuel type. We rated the annual energy consumption cost Excellent for a gas model but only Fair for an electric, but both rate Very Good for energy efficiency.

Can you take two showers at once with tankless water heater? ›

In other words, they can only supply so much hot water at a time. Depending on the flow rate of your water heater, you may be able to take a shower and use hot water at the kitchen sink at the same time, but you probably won't be able to run two showers and the kitchen sink.

Do you need a water softener with a tankless water heater? ›

It is not required to install a water softener, but if you live in an area that has hard water it will eventually harm the performance of your tankless water heater.

Do tankless water heaters increase electric bill? ›

Obviously, there are many variables that determine how much exactly does running an electric tankless heater cost. Nonetheless, according to the Department of Energy, tankless units do spend less electricity than conventional water heaters that run of electricity.

Is gas or electric better for tankless water heater? ›

Electric tankless water heaters are typically around 98 percent or more efficient while gas tankless water heaters are around 80-85 percent efficient. A gas tankless water heater can be cheaper to run and will typically last longer.

How much does it cost to install tankless water heater? ›

The national average for tankless water heater installation cost is around $2,800. Depending on the model, the units themselves usually cost between $500 and $2,000, with installation adding another $500 to $1,500. However, for large or specialty units, you may pay as much as $6,600 in total costs.

Can I use a hot water heater for radiant floor heat? ›

Use a Water Heater to Make Radiant Floor Heat Instead of a Boiler. Many people use a water heater instead of a boiler for radiant floor heat because it COSTS LESS. A hot water heater saves money when used in this way. Certainly, cost is important, but there are many other important factors as well.

What is the cheapest way to heat your home in the winter? ›

Reverse-cycle air conditioning is the most cost-efficient ways to heat your home quickly, while portable electric heaters can be more expensive to run and take more time to heat up.

Which type of heater is cheapest to run? ›

Generally speaking, Halogen heaters are one of the most inexpensive types of electric heater. They average around 1200W in terms of power output and because they provide instant-heat at close quarters, you shouldn't need to leave them on for long periods of time.

How do I choose a tankless water heater? ›

When buying a tankless water heater, take into account the size of your house, the water-flow rate of your faucets, the temperature of the water before it heats up and how hot you want your water to be. With those calculations, a Lowe's associate can help you find the best tankless water heater for your home.

How big of a tankless water heater do you need? ›

Tankless water heaters measure their flow rate in Gallons Per Minute (GPM). A family of 4 should look for a tankless water heater that can produce 7 gallons of hot water per minute. Most families use about 6.5 GPM during peak times.

What size tankless water heater do I need to replace a 75 gallon water heater? ›

Sizing Guide for Residential Tankless Water heater
Household OccupantsUsageCapacity Required (Measured in Gallon)
3-4 peopleHigh50-75
5+ peopleRegular/Low50
High75
6 more rows

Can you use a hot water heater for heat? ›

Heating the House With a Water Heater

This is an option only if your house is very well sealed and well insulated, or if you live in a mild climate. The hot water is used to heat the fan coils for your home heating system, and the heat is then distributed through ducts, as with a standard furnace.

Can I use a tankless water heater for hydronic heating? ›

With a hydronic air handler, a tankless water heater can perform two jobs, providing heat and domestic hot water to a home. Hydronic forced-air heating can also address two common concerns with electric backup heat, Goyal says: the smell and the cost.

Can I use a hot water heater as a boiler? ›

Most heating guys will tell you that you can't use the lowly water heater to fire your hydronic heating system, but they often don't give any good reasons to back up their claims other than they've always used boilers. Or they'll tell you water heaters are unsafe, inefficient, and expensive hydronic heat sources.

How do you add radiant heat to an existing hot water boiler system? ›

Can I use my existing boiler for both radiant heating and baseboard radiators? Yes you can. All you need to do is provide a Radiantec mixing valve to step down the temperature of the water to the radiant circuits. You mix hot water from the boiler with return water from the floor to provide a lower temperature.

What is a hydronic water heater? ›

Hydronic heat—boilers warm your home using hot water—not air like a furnace uses—hence the term hydronic. Boilers heat but don't actually boil water, and then disperse it as either hot liquid or steam through pipes to radiators, coils, or radiant floor systems.

Are tankless water heaters more efficient? ›

According to Energy.gov, “For homes that use 41 gallons or less of hot water daily, demand (or tankless) water heaters can be 24% to 34% more energy efficient than conventional storage tank water heaters.” Tankless water heaters (if gas-fired) will save homeowners over $100 annually the longer they remain in service.

Which is better forced air or hot water heat? ›

Boilers and Hot Water Heat

Once the water is heated and makes its way through the system, it continues to heat the space — that can make your home feel warmer longer, making radiant heat more consistent, energy efficient, and cost-effective than a forced air system.

Can a tankless water heater heat a whole house? ›

What is a Tankless Water Heater? These water heating systems don't utilize a tank to store heated water. They provide on-demand hot water to either a whole house, a local tap, or even an appliance.

What boiler is best for underfloor heating? ›

Underfloor heating water systems are made to be used with heat pumps as they require only a very low water temperature. The best boiler to use is a condensing boiler as they are very efficient. A condensing boiler works by using the latent heat created using another heat exchanger fitted within.

How many gpm tankless do I need? ›

SELECTING A TANKLESS WATER HEATER

Consider how many of these needs you may have simultaneously to determine the maximum flow rate you require. For a home with 1 bathroom, we recommend 6-7 GPM; 2 bathrooms, 8 – 9 GPM; and 3+ bathrooms, 9-11 GPM.

Can I use a tankless water heater as a boiler? ›

Absolutely! Not only can you install a Tankless ASME Boiler, but with a Combi System the same unit can be used for domestic hot water as well. Not all Tankless Units are considered boilers, so make sure to look for a unit with an ASME.

What size water heater is considered a boiler? ›

A water-heating device that exceeds any one of the following should be classified as a water boiler: 120 gallons (454.2 liters) nominal water storage capacity; 160 psi (1103.2 kPa) operating pressure; 210 degrees Fahrenheit (99 degrees Celsius) operating temperature; or.

What is the cheapest way to heat my house? ›

Gas boiler

A gas boiler is still the cheapest way to heat your home – though that's set to change soon, with the cost of gas rising more than twice as quickly as electricity.

Does a plumber install radiant heat? ›

However, servicing it is better left for a professional plumber. If you think you're good with minor fixtures like sink leaks and basic ductwork, a radiant heating system is a whole other story that should not be serviced by anyone other than a professional plumber.

Can you put radiant heat on existing concrete slab? ›

Radiant heat remodels can go into a new concrete floor addition, under an existing subfloor or in a thermal panel, like Thermalboard, on top of a subfloor or existing concrete slab.

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3. Uponor Residential Radiant Heating Installation Applications
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