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6 (Gas & Electric) Best Water Heater For Radiant Floor Heat [2021]

Interest in radiant floor heat has surged over the last few years. But unfortunately, online information about it is really scarce. People still get confused on how to calculate the heat loss value of their home, how many BTU/h’s water heater they need, or what would be the best water heater for radiant floor heat. So, we decided to publish this article to answer all your questions in detail. We also recommend these 6 (3 gas-fired and 3 electric) best water heaters for radiant floor heat, in case you want to buy one.

Heads up: As radiant floor heaters, we always prefer a gas-fired condensing type (efficiency over 90%) tankless water heater over an electric water heater. Sure they are expensive but are way more powerful than any electric water heater. Most importantly, a gas-fired tankless water heater has a comparatively low operating cost and is more suitable to be used in the harshest icy weather. If you live in the northern part of America or in Canada, where the temperature can go as low as -20 degrees Fahrenheit (ca. -7 °C), a gas-fired tankless water heater would be the best heat source for a radiant floor in your home.

3 Best Electric Water Heater For Radiant Floor Heat

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Gas-fired 3 Best Water Heater For Radiant Floor Heat

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1) Ecosmart ECO 27 (6.5 GPM): Best Electric tankless water heater For Radiant floor heat

Out of all the electric water heaters in the market, ecosmart Eco 27 has our first recommendations as to the best electric water heater for radiant floor heating system.

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Ecosmart Eco 27 is a compact & lightweight water heater. It weighs only 10.98 pounds (4.98 kg) and is made of copper & stainless steel. It comes in white and has a stylish digital temperature controller with a nob.

[amalinkspro type=”showcase” asin=”B002635ODW” apilink=”https://www.amazon.com/dp/B002635ODW?tag=home0446-20&linkCode=osi&th=1&psc=1″ new-window=”true” addtocart=”false” nofollow=”true” sc-id=”4″ imgs=”LargeImage” link-imgs=”false” specs=”~~~~~~~~~~~~~~~~~~~~~~~~” btn-color=”#ff9900″ btn-text=”Buy on Amazon” alignment=”alignnone” hide-prime=”0″ hide-image=”0″ hide-price=”1″ hide-button=”0″ width=”750″]EcoSmart ECO 27 Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self Modulating Technology,White[/amalinkspro]
  • Ecosmart Eco 27 is the most popular electric tankless water heater in the market.
  • It has got the latest Self-modulating technology from Ecosmart.
  • Hot Water Flow: 6.5 GPM, Energy-Efficiency: 99.8%
  • Power: 27 KW or 92,128BTU/h
  • Max Space Coverage: 1500 -1800 square feet
  • It can be only used in closed-loop heating systems
  • It doesn’t come with a preinstalled recirculation pump

Power Source And Flow Rate: Ecosmart Eco 27 is a 27 KW (92,128BTU/h) electric tankless water heater. It uses 3 heating elements to heat water and each element needs 9kW of power. Other key electrical requirements of this water heater are 240 volts, 3 x40 AMP breakers, 112.5 maximum power (AMP), 3 · 8 AWG wire.

Thanks to the self-modulating technology, it provides 6.5 gallons (24.61 l) of hot water flow per minute. In northern states where the underground water temperature can go down to 37 F, you will get somewhere between 2.5-3 gallons (11.36 l) of hot water per minute.

Depending on the weather, Ecosmart Eco 27 can manage a 1500 -1800 square feet (ca. 167 m²) house. If you live in icy cold states (North Dakota, Maine, Minnesota) and your house is bigger than 2000 square feet (ca. 186 m²), you should use Ecosmart Eco 36. It’s a 36KW water heater and 33% more powerful than Eco 27.

Closed-loop vs open loop: We recommend you use Eco 27 only in a closed-loop radiant heating system. As a 27 KW water heater, it cannot supply adequate hot water to the shower and the radiator simultaneously. So, there’s no point trying to install it in an open-looped system.

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A little advice: If you compare the price of 2 electric heaters with a gas-fired heater, you will see 2 electric heaters cost less than a gas-fired heater. As a cost-effective option, you can buy 2 ecosmart Eco 27, one for your shower and another one for a radiant floor heating system.

Energy-efficiency: Ecosmart uses a combination of copper and stainless steel to achieve optimum efficiency for all of its water heaters. Ecosmart Eco 27 is no different. It’s a 99.8 % energy-efficient water heater and ecosmart claims their water heater can reduce your water heating cost by 50%.

Recirculation pump: Ecosmart Eco 27 or any of their electric water heaters do not come with a recirculation pump. You will need to buy a pump separately for your radiant floor heating system.

Warranty: For American and Canadian users: with ecosmart Eco 27, you will get a Limited Lifetime a1 Warranty on heat Exchanges, Electronics, and Elements. The Warranty only covers the cost of the heater & does not cover labor or any incidental damages. For other users: A 5-year Limited Warranty on heat Exchanges, Electronics, and Elements.

2) Stiebel Eltron Tempra 29 (7 GPM) : Best Electric water heater For Radiant floor heat

The next hot water heater we recommend for you is Stiebel Eltron Tempra 29 Plus. It is a German-made high-quality electric tankless water heater from Stiebel Eltron company. It’s an excellent machine with decent water flow & slightly more powerful than Eco 27.

Steibel Eltron used high-quality “Alpine White Sheet Steel” to build this water heater. Its seismic-proof construction and advanced safety features have made it a popular water heater in the market. Its advanced self-modulating power technology ensures a constant temperature of hot water and lets you customize the temperature settings to your needs.

[amalinkspro type=”showcase” asin=”B07GYQHWYJ” apilink=”https://www.amazon.com/dp/B07GYQHWYJ?tag=home0446-20&linkCode=osi&th=1&psc=1″ new-window=”true” addtocart=”false” nofollow=”true” sc-id=”4″ imgs=”LargeImage” link-imgs=”false” specs=”~~~~~~” btn-color=”#ff9900″ btn-text=”Buy on Amazon” alignment=”alignnone” hide-prime=”0″ hide-image=”0″ hide-price=”1″ hide-button=”0″ width=”750″]Stiebel Eltron Tankless Water Heater – Tempra 29 Plus – 29 kW, 7 GPM [/amalinkspro]
  • Stiebel Eltron Tempra 29 Plus is an electric water heater of the highest quality.
  • Hot Water Flow: 7.0 GPM, Energy-Efficiency: 99%
  • Power: 29 KW or 98,952 BTU/h
  • Max Space Coverage: 2000-2200 square feet
  • It can be only used in closed-loop heating systems
  • It doesn’t come with a preinstalled recirculation pump

Power Source And Water Flow Rate: Tempra 29 plus is a 29-kilowatt or a 98,952 BTU/h water heater. Based on the water flow rate, Tempra 29 plus is a better performer than Eco 27. You can get a maximum of 7 GPM water flow rates from Tempra 29. And in the coldest States of the USA, the water flow will be between 3.5 – 4 gallons per minute. It will be sufficient to manage a house of 2000-2200 square feet (204.39 m²) at max.

Closed-loop vs open-loop: Tempra 29 is a moderately powerful water heater, still we don’t recommend using it in an open-loop system. Our advice of buying 2 electric tankless water heaters (if needed) also applies to Tempra 29 as well.

Energy-efficiency: Stiebel Eltron Tempra 29 plus is a 99% efficient hot water heater and uses cooper alloy-made heating chambers to heat water.

Recirculation Pump: It does not come with a recirculation pump.

Warranty: With Tempra 29 you will get a 7-year leakage & a 3-year parts warranty.

3) Rheem RTEX-36 (8 GPM): Best Whole House Electric Tankless Water Heater

The 3rd water heater we recommend for you is Rheem RTEX-36 KW tankless water heater. It’s a very powerful water heater. In fact, it’s the most powerful among our recommended 3 electric water heaters. In our opinion. It is the best whole house electric tankless water heater.

For a 36KW water tankless water heater, we would say it’s a pretty compact piece of a machine weighing only 22.7 pounds (10.3 kg). It has a body dimension of 4 × 22× 19 inches (ca. 48 cm). It comes in gray color. At the front, you will get a digital thermostatic control with an LED display. The controller gives you easy access to set your preferred water temperature with +/1-degree accuracy.

[amalinkspro type=”showcase” asin=”B01MZBQXP0″ apilink=”https://www.amazon.com/dp/B01MZBQXP0?tag=home0446-20&linkCode=osi&th=1&psc=1″ new-window=”true” addtocart=”false” nofollow=”true” sc-id=”4″ imgs=”LargeImage” link-imgs=”false” specs=”~~~~~~~~~” btn-color=”#ff9900″ btn-text=”Buy on Amazon” alignment=”alignnone” hide-prime=”0″ hide-image=”0″ hide-price=”1″ hide-button=”0″ width=”750″]Rheem 240V 4 Heating Chambers RTEX-36 Residential Tankless Water Heater, GRAY[/amalinkspro]

Power Source Flow Rate: Since it’s a 36KW (1,22,837 BTU/h) water heater, it has 4 heating chambers. Each element uses 9kw of electricity to provide ample hot water supply. The maximum hot water outflow you can get out of it is 8 gallons (30.28 l) per minute. 8 GPM is sufficient to warm up your house and for your shower. To those who are living in big houses in the countryside, we highly recommend RTEX-36 for you.

Closed-loop us open loop: since it has high water output rate you can use it in both open-loop and closed-looped systems. In a closed-loop system, it can warm up a house of 2500 square feet (ca. 232 m²). In an open-loop system, its water supply is enough to simultaneously warm up a house of 2000 square feet (ca. 186 m²) and one shower/ kitchen.

Energy Costs & Efficiency: RTEX-36 is a 99.8% energy-efficient radiant floor heater thanks to its copper-made four heating chambers. Moreover, it has advanced self-modulation technology. The technology allows it to use the heating elements one by one or all at once. During low water demand, it uses only one of the heating chambers to reduce electricity bills. And when high water flow is required, it fires up all the heating chambers to fulfill your needs.

Those heating chambers are durable and most importantly field serviceable. Meaning, if any one of the heating chambers malfunction you can repair it without disassembling the entire machine.

Recirculation pump: Rheem RTEX-36 does not come with a recirculation pump

Warranty: For RTEX-36, Rheem gives you a 5-Year heating chamber and a 1-year part limited warranty.

4) Rinnai RUR199ip (11 GPM): Best Propane Water Heater For radiant floor heat

Rinnai Rur199ip is the most powerful and most energy-efficient tankless water heater that money can buy. It is the latest water heater from Rinnai and undeniably the best propane tankless water heater for radiant floor heating systems.

Models: The Rinnai RUR199ip is made for internal installation & powered by liquid propane. It has 3 more variants. Those are Rur199in (for internal installation & natural gas-fueled), Rur199en (for external installation & natural gas-fueled), Rur199ep (for external installation & liquid propane-fueled). By clicking on the model number you can go to amazon to check the latest price and description of these water heaters. By the way, if you want you can check our full review of Rur199in here.

[amalinkspro type=”showcase” asin=”B07CVLCMHK” apilink=”https://www.amazon.com/dp/B07CVLCMHK?tag=home0446-20&linkCode=osi&th=1&psc=1″ new-window=”true” addtocart=”false” nofollow=”true” sc-id=”4″ imgs=”LargeImage” link-imgs=”false” specs=”” btn-color=”#ff9900″ btn-text=”Buy on Amazon” alignment=”alignnone” hide-prime=”0″ hide-image=”0″ hide-price=”1″ hide-button=”0″ width=”750″]Rinnai RUR199iP RRUR199iP, RUR199ip-Propane/11 GPM[/amalinkspro]
  • Rinnai Rur199ip is the most powerful water heater.
  • Hot Water Flow: 11 GPM, Energy-Efficiency: 96%
  • Power: 15000BTU/h – 199,000BTU/h
  • Max Space Coverage: 4000-4500 square feet
  • It can be used in both open loop and closed loop heating systems
  • Energy-star certified and eligible for a federal tax credit
  • It comes with a preinstalled recirculation pump

You know, Natural gas tends to coagulate in icy weather. And when it does, gas pressure drops. Since you will be using the water heater on cold nights, gas supply pressure in your house might drop. Frequent drops in gas pressure are not good for any water heater. It messes with the heating mechanism and reduces the expected lifespan. So, for those who don’t have a high-pressure gas supply connection, a propane-powered water heater would be a good choice.

Power: The BTU/h rating of this machine clearly tells how powerful this water heater is. Rur199ip has a minimum of 15,000 BTU/h and a maximum of 199,000 BTU/h ratings. With the default factory setting, it raises the water temperature to 140-degrees Fahrenheit. But If you tweak the system a little, you can get 160-degrees Fahrenheit hot water. Rur199ip has a whooping 11 gallons (41.64 liters) per minute water supply rate. No matter how big your house is or how cold it gets at night, Rinnai Rur199ip will supply plenty of hot water to warm up your house.

Open-loop vs closed-loop: Since Rur199ip is an incredibly powerful water heater, you can use it in both open-loop and closed-loop heating systems. If you use it in an open-loop heating system, it will be able to manage up to 2500-3000 square feet (ca. 232 square meters) of space. Along with it, you can expect to get hot water in 3-4 fixtures simultaneously.

But if you use it as a dedicated water heater only to warm up your house, it will be sufficient to heat up 4000-4500 square feet (ca. 372 m²) space even in the coldest state of the U.S.A.

Energy- Efficiency: Now that you have got an idea of its power, let’s talk about its energy efficiency. Rur199ip is a condensing type tankless water heater and uses two ‘Stainless Steel made Heat Exchangers to improve efficiency. Due to this reason, it got an impressive 96% energy efficiency rating. In simple English, by putting 1 dollar in it, you will get 96 cents worth of hot water. The energy factor rating of Rur199ip is 0.96 and the uniform energy factor rating is 0.93.

Energy-Star Certification: Its impressive energy efficiency helps it to get an ‘Energy Star’ certificate. If you buy this energy star-certified product, you will get up to 300 dollars tax credit. Also, it is an Ultra-low NOx-certified heater that complies with south coast air quality management.

Recirculation Pump: This latest water heater from Rinnai is not only recirculation capable but also comes with a preinstalled recirculation pump. As you might know, recirculation capability and a recirculation pump is a must-have feature for any water heater to be used for radiant heating. A recirculation pump recirculates hot water from the heater through the radiant tube to the heater again. It speeds up the heating mechanism and saves you from energy wastage.

Since Rur199ip comes with a Rinnai recirculation pump, it saves you from the hassle of buying and installing a third-party after-market recirculation pump.

Remote monitoring system: For your convenience Rinnai included a built-in Wi-Fi module in Rur199ip. With the Rinnai app, available both for iPhone and Android, you can control & monitor your water heater. You can also diagnose your system for troubleshooting through the app. This “Alexa” compatible water heater can be controlled with voice commands also.

Warranty: With Rur199in, you get a ‘Residential Factory’ Warranty. One hundred twenty months for heat exchanger, 12 months for labor, 60 months for parts.

5) Takagi T-H3-DV-N (10 GPM ): Best Tankless Water Heater For Radiant Floor Heating

Takagi T-H3-DV-N is the next water heater that we recommend for your radiant floor. On paper, Rur199ip defeats it by a slight margin. But considering its performance & reasonable price, Takagi T-H3-DV-N is overall the best water heater for radiant floor heat. Most importantly, it is the only natural gas-fired water heater that is actually certified to be used for radiant heat. This commercial-grade water heater is suitable for mansions, condos, motels, ranches, and large apartments.

See also  Rinnai Rur199in Reviews [2021]: Most Powerful Condensing Tankless Water Heater

Models: Takagi T-H3 model has 2 variants. One is powered by natural gas (T-H3-DV-N) and the other one is powered by liquid gas (T-H3-DV-P). Both of the models are made for indoor usage and are equally powerful. You can compare the price of these models here on amazon now. The latest price of Natural-gas powered T-H3 & the latest price of Propane powered T-H3.

[amalinkspro type=”showcase” asin=”B00DDPZ5HM” apilink=”https://www.amazon.com/dp/B00DDPZ5HM?tag=home0446-20&linkCode=osi&th=1&psc=1″ new-window=”true” addtocart=”false” nofollow=”true” sc-id=”4″ imgs=”LargeImage” link-imgs=”false” specs=”~~~~~~~~~” btn-color=”#ff9900″ btn-text=”Buy on Amazon” alignment=”alignnone” hide-prime=”0″ hide-image=”0″ hide-price=”1″ hide-button=”0″ width=”750″]Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute, 199,000 BTU[/amalinkspro]
  • Takagi T-H3-DV-N is a certified water heater for radiant floor heat.
  • Hot Water Flow: 10 GPM, Energy-Efficiency: 93%
  • Power: 15000BTU/h – 199,000BTU/h
  • Max Space Coverage: 4000-4200 square feet
  • It can be used in both open loop and closed loop heating systems
  • Energy-star certified and eligible for a federal tax credit
  • It doesn’t come with a preinstalled recirculation pump

Power: Just like Rinnai RUR199in, Takagi T-H3-DV-N has a minimum of 15,000 BTU/h and a maximum of 199,000 BTU/h ratings. Takagi T-H3-DV-N can provide at a maximum rate of 10 gallons per minute. If you compare with RUR199in’s water flow rate, Takagi T-H3-DV-N is 9% less powerful. Yes, on paper Takagi T-H3-DV-N is a little weaker but practically they are equally powerful. Because 10 gallons of hot water per minute is more than you will ever need to warm up your house.

One more thing, Takagi’s multi-link feature allows you to connect up to 20 T-H3 models together. Once connected, those water heaters work as a single unit and can be operated from a single control box. Multilink works great in commercial applications where more than one water heater is needed.

Open-loop Vs Closed-loop: Without any doubt, you can use it in both open-loop and closed-loop heating systems. If you use it in an open-loop heating system, it will be able to manage up to 2000-2500 square feet (ca. 232 square meters) of space. Along with it, you can expect to get hot water in 2-3 fixtures simultaneously. And if you use it in a closed-loop system, it will be sufficient to heat up 3500-4000 square feet (ca. 372 m²) space.

Energy efficiency: Takagi T-H3-DV-N is a 93% energy-efficient water heater. Unlike Rinnai, Takagi used commercial-grade copper alloy to make its heat exchangers. While copper alloy transfers heat faster than stainless steel, it slightly reduces energy efficiency as well.

Compared to RUR199in, it is 3% less energy efficient and this is the only reason why we are recommending it in the second place.

Energy Star Certification: Still, a 93% efficiency rating was enough to get an ‘Energy Star’ certificate. So, you are entitled to a tax credit with this water heater as well. Also, it is an Ultra-low NOx-certified heater that complies with south coast air quality management.

Recirculation pump: As of now, you might have noticed Takagi T-H3-DV-N costs several hundred dollars less than RUR199in. Because this water heater doesn’t come with a preinstalled recirculation pump. Since it is recirculation capable and compatible with most third-party recirculation pumps, you will have no trouble finding one for your Takagi T-H3-DV-N tankless water heater.

Warranty: With Takagi T-H3-DV-N you will get a 15-year limited warranty on the heat exchanger in residential applications, a 5-year limited warranty on the heat exchanger in commercial applications, a 5-year limited warranty on all parts.

6) Noritz NRC66DVNG(6.6 GPM) : Best Natural Gas Water Heater For Radiant Floor Heating in Small Houses

The third gas-fired tankless water heater we recommend for you is the Noritz NRC66DVNG. It is the best budget tankless water heater for radiant floors. If you have a small house and are looking for a condensing type (efficiency over 90%) under the 1000-dollar-range, then Noritz NRC66DVNG is for you.

Models: Noritz NRC66DVNG is made for indoor uses. It has a direct system and runs by natural gas. It has 3 more variants NRC66ODNG (for outdoors & runs by natural gas), NRC66DVLP (for indoors & runs by propane), NRC66ODLP (for outdoors and run by propane). You can compare the latest price of these water heaters on AMAZON by clicking on the model number.

[amalinkspro type=”showcase” asin=”B00CI4YS3G” apilink=”https://www.amazon.com/dp/B00CI4YS3G?tag=home0446-20&linkCode=osi&th=1&psc=1″ new-window=”true” addtocart=”false” nofollow=”true” sc-id=”4″ imgs=”LargeImage” link-imgs=”false” specs=”~~~~~~~~~” btn-color=”#ff9900″ btn-text=”Buy on Amazon” alignment=”alignnone” hide-prime=”0″ hide-image=”0″ hide-price=”1″ hide-button=”0″ width=”750″]Noritz NRC66DVNG Indoor Condensing Direct Tankless Hot Water Heater, 6.6 GPM – Natural Gas[/amalinkspro]
  • Noritz NRC66DVNG natural gas-powered affordable water heater for small houses.
  • Hot Water Flow: 6.6 GPM, Energy-Efficiency: 93%
  • Power: 15000BTU/h – 120,000BTU/h
  • Max Space Coverage: 1500-1800 square feet
  • It can be only used in closed-loop heating systems
  • Energy-star certified and eligible for a federal tax credit
  • It doesn’t come with a preinstalled recirculation pump

Power: Noritz NRC66DVNG is a moderate-powered hot water heater. It;s BTU rating ranges from 15,000 BTU/h — 120,000BTU/h. The maximum flow rate it can provide is 6.6 gallons (24.98 l) per minute. Noritz NRC66 is suitable to warm up a house of 1500-1800 square feet (ca. 167 m²).

Open-loop vs closed loop: The maximum hot water flow of Noritz NRC66 is 6.6 gallons (24.98 l) per minute. So, it can only be used in a closed-loop radiant system.

Energy Efficiency: Since it’s a condensing-type water heater, Noritz NRC66 has a 93% efficient rating. Indoor, outdoor, natural gas, or propane, all the models have the same energy efficiency.

Energy Star certificate: Yes, Noritz NRC66 has an energy star certificate and is eligible for a tax credit.

Warranty: With Noritz NRC66 you will get a 12-Year Limited Heat Exchanger Warranty for Standard Residential Use. A 5-Year Limited Parts Warranty and a 1-Year Reasonable Labor Warranty.

Best Water Heater For Radiant Floor Heating System: Buying guide

1) How big of a water heater do I need for radiant heat?

The size of a water heater that you need for our radiant floor heat depends on the construction and total area of your house. First, you need to calculate the “Heat Loss Value” for your home. And then we will decide, how many BTU/h radiant floor heaters are suitable for your home.

You can use the chart below, as a rough “Rule Of Thumb” guide for calculating the heat loss value for your home.

The assumption for this chart: The temperature outside the house gets Zero degrees Fahrenheit at night and the preferred room temperature is 70 degrees Fahrenheit.

The temperature difference is = Preferred room temperature — Outside temperature

= 70 degrees Fahrenheit

Now, the weather and preferred room temperature in your state might be different from ours. In that case, use the formula to find out the temperature difference first. If the temperature difference is more than 70 degrees Fahrenheit, you will need a more powerful (20,000-30,000 BTU/h) water heater than that of the chart tells you.

CeilingFactor FTotal AreaHeat loss value = Factor F * Total Area
R-11 Insulation7
R-19 Insulation4
R-30 Insulation2.5
R-38 Insulation2
Heated Space Above
Heat Loss chart For Ceiling
WallsFactor FTotal AreaHeat loss value = Factor F * Total Area
R-11 Insulation7
R-19 Insulation4
Interior
Heat Loss Chart For Walls
FloorFactor FTotal AreaHeat loss value = Factor F * Total Area
Uninsulated Wood Frame Over Crawl Space15
R-11 Insulation over crawl space7
R-19 Insulation over crawl space4
R-30 Insulation over crawl space2.5
Uninsulated Wood frame over Unheated Cellar7
R-11 insulation Over
Cellar
3
R-19 insulation Over
Cellar
2
R-30 insulation Over
Cellar
1
Uninsulated slab on Grade11.5
R-10 insulated Slab On Grade3.5
Heated Space below
Heat Loss Chart For Floor
WindowsFactor FTotal AreaHeat loss value = Factor F * Total Area
Single Glazed
Single Glazed With Storm
Double Glazed
Double glazed ( low e)
Heat Loss Chart For Windows
Exterior DoorsFactor FTotal AreaHeat loss value = Factor F * Total Area
2 Inch Wood30
1.75 inch Steel With Insulated Core30
Heat Loss Chart For Doors

Example: How to calculate heat loss value for an entire house?

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Suppose, you have a 2000 square feet 1-story house. It is 60 feet in length, 40 feet in width, and 12 feet high. For simplicity, let’s assume it has only one door and two windows at the front.

Before we calculate the heat loss for value for this house we have to calculate the total area from where the heat escapes.

heat-loss-calculation
Heat Loss Calculation

Each house has a total of 6 sides: Up (ceiling), down (floor), left, right, front, and back.

  1. Heat loss through the ceiling: In this example, the ceiling has R-11 insulation, So, factor F for the ceiling is 7. The total area of the ceiling is 2400 suture feet. So, heat loss through the ceiling is 7×2400= 16800 BTU/h
  2. Heat Loss Through the Floor: The house is a 1-story building and has Uninsulated Wood Frame Over Crawl Space. Factor F for the floor in 15 and heat loss through the floor is 2400× 15= 36000 BTU/h.
  3. Heat through the Left exterior wall: say, the house has R-11 insulation on all the exterior walls(left, right, back and front). So the Factor F for the exterior wall is 7. The total area of the left exterior wall is 40×12= 480 square feet. Heat loss through the left wall will be 480× 7 = 3360 BTU/h.
  4. Heat through the right exterior wall: heat loss through the right wall will be the same as through the left wall, 3360 BTU/h.
  5. Heat loss through the Back wall: Factor F is 7 and the total area is 60×12= 720 square feet. So, heat loss is 720×7= 5040 BTU/h
  6. Heat loss through the front wall: At the front, there is a door (5 by 7 feet) and 2 windows (4 by 5 feet). So, We need to subtract the area of the door and windows from the front wall. The total area of the front wall is (60×12) — (35+20+20) = 645 square feet. Since factor F is 7, total heat loss through the front wall is 645×7 = 4515 BTU/h7
  7. Heat loss through the door: The external door is made of 2-inch wood and the factor f for the door is 30. Heat loss through the door is 30× 35= 1050 BTU/h.
  8. Heat loss through the window: The house has two, single glazed windows and the total area of the 2 windows is 20+20 = 40 square feet. If factor F is 70, heat loss through the window is 70×40= 2800 BTU/h.

In this example, the heat loss value of this house is 16800 BTU/h + 36000 BTU/h +3360 BTU/h +3360 BTU/h + 5040 BTU/h +4515 BTU/h+ 1050 BTU/h+ 2800 BTU/h = 72625 BTU/h. So any water heater that has a BTU rating of 72625BTU/h or more, is suitable for the house.

2) Why we recommend condensing type gas-fired tankless water heaters for radiant floor systems?

Out of all the benefits of radiant floor heat, low operating cost is the most significant. And who does know the more energy-efficient water heater you use, the lower the operating cost gets. Mainly there are two types of gas-fired tankless heaters.

1) Condensing type

2) Non-condensing type

Non-Condensing Hot Water Heater: The design and manufacturing process of a non-condensing water heater is pretty easy. They use only one heat exchanger and one burner. Non-condensing type radiant floor heaters usually cost under 1000-bucks-range. But their energy efficiency is pretty low, usually around 80-82%. Due to this reason, they are not suitable for radiant floor heat. Moreover, none of the non-condensing type water heaters are not energy-star certified, So, you won’t get tax credit benefits either.

Condensing Hot water Heater: Condensing type water heater is a complex piece of machinery. They use two heat exchangers, one burner, one neutralizer. They are designed by industry experts to serve one single purpose “ maximum water outflow with maximum energy- efficiency”. This is the sole reason why they are suitable for radiant floor heat.

We know, maximum condensing radiant floor heaters cost about 1200-2000 dollars. The initial cost may seem overwhelming but try to think of it as an investment that will pay for itself over the next 10-15 years.

Also, the government promotes condensing radiant floor heaters by giving them energy star certificates and tax credit.

3) Why we recommend electric tankless water heaters for radiant floor systems?

Electric tankless water heaters are affordable and easy to install. The installation cost and installation time associated with an electric hot water heater are pretty low. Since electric water heaters don’t waste energy, almost all electric tankless water heaters are 99% efficient. In remote places where natural gas or propane is unavailable, electric water heaters can be a game-changer.

Is radiant floor heat worth it?

1) Low Utility Bills Due to Energy Savings

The water-based heating system is far more efficient than the electric-based heating system. In traditional electric heating systems, the electric mat needs to heat at 149-167 degrees Fahrenheit to achieve a comfortable room temperature.

Whereas, water-based radiant floor heat needs only 85-95 degrees Fahrenheit hot water to heat a room. In comparison, water-based radiant floor heat can reduce your utility bill by up to 30%.

2) No maintenance Required

Floors for radiant heating don’t require any maintenance. Once, you are done placing PEX tubes under your floor, you can be certain that nothing will happen to the tubes for the next 20-25 years. During its lifespan, you might need to change/repair your water heater and electrical panels but your flooring installation will remain unchanged for two decades.

3) Uniform Heating Provides More Comfort

Forced-air heating pushes hot air to heat a room. Oftentimes, indoor furniture blocks the hot air to reach every corner of the room. As a result, little bubbles build up in the room. Inside the bubble, it feels cold while in another area it feels warm. But a heated floor evenly warms up the floor and space above it. Evenly distributed heat provides more comfort In winters.

4) Automatic and Silent Heating System

Radiant floor heating system is an automatic and silent system. Once you set your preferred temperature in the thermostat, the thermostat will do all the work for you. It will call for hot water when the room temperature drops and automatically shut off the water supply when the room reaches your desired temperature. And all of it will happen in complete silence. So, nothing will disturb you while you are in the bed for a good night’s sleep.

So to answer your question we would say yes, radiant floor heating works and it is worth it.

Best Condensing Tankless Water Heater In 2021

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Full Review: “Value For Money” Non-Condensing Tankless Water Heater Rinnai V65in Reviews in 2021

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3 Comments

  1. Where is the information on the three electric water heaters for radiant floors?

    Can you please email my that information.
    thank you.

    • We are sorry, Sir. Due to errors, some information on this page was missing. The problem has been solved. You can now find all information about electric water heaters for radiant floors.

  2. The Noritz NRC66DVNG is a great tankless water heater for us. We can have two showers (this is not common) at the same time and the temperature is not interrupted. A washing machine or dishwasher combined with a shower at the same time is also no problem. It gets nice and hot and constant

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