Home » How To Find An Affordable and Reliable Boiler for Radiant Floor Heat?

How To Find An Affordable and Reliable Boiler for Radiant Floor Heat?

Stiebel Eltron Tempra Plus
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Editor's Choice
Weil McClain GV90
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Best on the Market
Rinnai RUCS75IN
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List of Top-Rated Boilers for Radiant Floor Heat

Radiant floor heating is a very simple process; it is a “snake” of pipes that sits under your flooring and passes hot water or electricity through the system to heat up the floor.

Radiant floor heat is actually a very comfortable and healthy heating process, and it continues to heat even when the system turns off, as the natural thermal retention properties of the materials slowly dissipate the heat over time, unlike a standard heating system that just heats up the air of the room.

The two forms that radiant floor heaters come have advantages and disadvantages. The electric floor heating system connects to your main electricity supply and is expensive to run since it gobbles up electricity. However, the cost of installation is very cheap, around a quarter of that for a water-based system. Also, electric-based systems can vary the heat levels at a much more efficient and immediate way.

Water-based radiant floor heaters are expensive to connect since they require a water source, a boiler, and pump unit. However, once installed, they are exponentially cheaper to operate than electric heaters, and as such, after the second year, recover their initial cost. As such, it is actually best to install a water-based system, rather than an electric one.

Here are the five best boilers for radiant flor heat systems:

The Best Boilers for Radiant Floor Heat Reviews


My Take: The Tempra® by Stiebel Eltron, is a 3 x 40 amp 28.8Kw, Single Phase 50 – 60 Hz, with x 8/2 AWG runs. This electricity powered tankless water heater is compact and efficient.


The Advanced Flow Control™ is a standard feature that automatically reduces the flow of water to assure that only hot water hits the pipes and does not start out by pumping in cold water through the system.

The Advanced Flow Control™ is exclusive to Tempra® Plus models, and it comes with another advanced feature, the Self-Modulation Energy Technology. This is not a flow control system, it is a heat modulator that checks the amount of energy being used to heat up the water in the system, and modulates it to reach optimum performance levels.
Another great feature is their Constant Temperature Output control, this is a knob that you set to the desired temperature, and the CPU sets the heating system to reach your preset temperature based on the sensor readings. This is an all-electronic system, there are no mechanical moving parts, making this a maintenance-free technology.
The Tempra® dimensions are 165/8˝/ 42.0 cm x 14½˝ / 36.9 cm 45/8˝ / 11.7 cm, and its overall working pressure is set to 150 PSI / 10 BAR.

The model comes with a standard ¾˝ NPT water connection that has a nominal water volume of 0.39 gal / 1.5 l, and the unit weight is 19.0 lb / 8.6 kg.


  • Tempra® Plus advanced Flow Control™
  • Unlimited supply of hot water
  • Sleek design saves space
  • No venting required
  • 7/3-year warranty


If you want an electric water heating system that is totally electronic and extremely advanced with German patented precision, then this is the home heater you want to install. Its priced fairly and is extremely efficient, reducing heating costs while providing a perfect heating solution.

My Take: The Weil McClain GV90+4 is a direct exhaust/ direct vent, NG/LP system that provides an average efficiency of 91%, with MBH at 70-175.


If its efficiency you seek, in a gas-powered boiler, then the Weil McClain is a perfect solution. Weil MacClain is a leader in heat exchangers, and this model delivers an AFUE 91%.

The primary heat exchanger is made from cast iron, and the secondary heat exchanger is made of stainless steel, which enables an exhaust heat energy recovery for increased energy savings. The primary cast-iron boiler comes with multiple venting options and can be vented using standard PVC accessories.

As such, the venting system provides a 90% saving in cost over conventional stainless-steel models and is capable of both direct venting or direct exhaust release that simplifies the installation process.

The cast iron heat exchanger design is wider than conventional models, and this extra 2” allows the sludge present in older systems to pass through for filtration and removal. The counter-flow design limits scaling, and thereby prolongs the life of the heat exchanger.

You also get their smart circulator system that uses 2 circulators that enables low return water temperatures, as low as 60°F and prevents condensation of flue gases.

This model comes with Molex® plug connectors for easy wiring.


  • 91% AFUE efficient
  • Durable cast iron primary heat exchanger
  • Condensing stainless steel secondary heat exchanger
  • Bespoke 7 pass heat exchanger design that maximizes heat transfer
  • Vents with PVC
  • Multiple ventilation options (direct vent, direct exhaust, concentric)


This is an exceptional water heating model that comes with a conversion kit to propane if required. It is also a very stable design that accounts for extreme low temperatures that can affect the water in the system.

My Take: The Rinnai RUCS75IN is ENERGY STAR® Qualified with an Energy Factor of .93 and a Uniform Energy Factor of .90. This is an interior model that comes with condensing technology by way of two heat exchangers that maximizes the energy efficiency durability.


10,300 BTU/h (Minimum) / 160,000 BTU/h (Maximum)

The Rinnai RUCS75IN provides a minimum of 10,300 BTU/h and a maximum of 160,000 BTU/h. The heat exchanger is a stainless steel tankless model with compact dimensions of 22” x 34” x 14.5” and weighs only 63 Lbs., this system uses natural gas and is for indoor construction only.

The maximum Hot Water Flow Rate is set at 7.5 GPM 28.4 l/min, and you have an energy factor of 0.9. What is stand out is that you get to control it via WiFi.

The combustion air intake pipe & Fittings, and the Exhaust vent pipe & Fittings are made of PVC schedule 40 ANSI/ASTM D1785 and the Termination Vent Screens are 3” Polyethylene.


  • Wi-Fi Capable: Yes
  • Works with both propane and natural gas.
  • The minimum flow rate is 0.26 GPM (1 l/min)
  • The maximum flow rate is 7.5 GPM (28.4 l/min)


If you are seeking a remote-controlled unit, where you can set the temperature without going to the tank, then this model will give you all you desire. It is exceptionally functional and very cost saving.

My Take: The Takagi T-KJr2 is a compact fully modulating, gas fired, tankless water heater that delivers a maximum of 140,000 BTU’s at a 6.60 flowrate.


Takagi is one of the world’s leading brands, this is an exceptional compact model for smaller homes, and will provide excellent heated water for smaller surfaces. This tankless model is a Low NOx system that has a BTU range from 19,500 to 140,000. The water connections use a standard ¾” connector based at the bottom of the unit.

This is a non-condensing, 4” direct vent, heat exchanger that is made of 99% pure copper and has a flow rate of 6.6. The dimensions of this model are 20.25” x 13.75” x 7.75,”and it weighs only 38 lbs.


  • Stainless steel venting
  • Complies with natural gas Low
  • NOx emissions of 40 ng/J or55 ppm


Takagi is the name that sells itself if you are deliberating between this model and another in Takagi, then you have to consider the heat and capacity of the devices. If you are deliberating between this and another make, don’t just stick with a Takagi.

My Take: The T-H3-DV-P is a commercial-sized heater for residential applications. This is an ENERGY STAR® qualified device that delivers performance even at an altitude of 10,000 ft.


The T-H3-DV-P is an extremely versatile 4” direct vent system that can be used directly or indirectly as well as integrated with storage tanks, recirculation systems, hydronic heating systems, radiant floor systems, and domestic and heating applications.

This model complies with Ultra-Low NOx regulations, and the primary heat exchanger and tubing are made of 99% copper alloy for perfect thermal transfer and provides a uniform Energy Factor of 0.93 for Liquid Propane.

The maximum flow rate of 8.4 GPM at 45°F temperature rise (5.4 GPM at 70°F rise)

The secondary heat exchanger is made of 316L stainless steel, this gives you improved corrosion resistance, and the system complies with Ultra-Low NOx regulations of less than 14 ng/J (<20ppm). The heating range is between 19,500 to 199,500 BTU, and the flow rate is set to 10. This is a 93% UEF device with a LEED rating of 1.5. The device dimensions are 22.50″ x 17.75” x 10.75,” and it weighs 59 Lbs.


  • Easy-Link up to four units without a Multi-
  • Unit Controller
  • Multi-Link up to 20 units with a Multi-Unit
  • Controller
  • Integrated controls and power cord as standard features


For larger homes and even small businesses, this is a perfect multipurpose solution provider, and you will save a lot of monthly bills in colder climates with this exceptionally optimized model. After all, it’s Takagi.


What is a Water Heater?

A water heater heats up water directly. This unit takes water from the supply pipe and heats this up, pumping the water into the pipes in the “hot” water pipe.

How does a Water Heater Work?

There are two types of water heaters, tankless and tanked. A tanked system stores the incoming water in a tank and then heats it up indirectly using gas or electricity via heating rods in the tank. Thermostats regulate the heat, and the moment you open the hot water tap, the system pulls cold water to replenish the loss in water in the tank. A tankless water heater provides direct heating to the pipes just before the tap. Usually, these systems maintain the heating process for as long as the tap remains open.

What is a Boiler?

A boiler turns the water into steam or into hot water, which is then moved through the pipes in your home to heat up the home.

How does a Boiler Work?

Boilers tend to be in a closed loop system, as such, they are not usually found in water supply heating systems, but for closed circuit heating systems, including radiant floor heaters. The water remains in the system and is constantly recycled through it.

What is the difference between the two?

A boiler is a device used to heat a home using steam and radiant heat techniques and is a closed system which rarely replenishes its supply of water from an external source. A water heater heats water that is constantly being replenished since it is connected to taps.

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