Roth FAQ Radiant Heating Systems

Roth FAQ Radiant Heating Systems

FAQ — Radiant Heating Systems

What is radiant floor heating and how does it work?

Radiant floor heating systems use your floor as a large radiator, like the big cast iron steam or hot water radiators, but because your floor has so many more square feet of surface area for heat transfer than a radiator, it only needs to be warm to keep your house comfortable. There are three ways to transfer heat: convection (heating the air), conduction (a warm object touches a colder object and transfers heat to it) and radiation (like sunshine). Radiant heating actually uses all three methods to heat your home but mostly works like the sun to warm you. It does not rely on warm air circulating around your house to keep you warm. It is similar to standing outside in the shade on a cold day and then taking a single step into the sunshine. You were cold in the shade, but the sunshine warms you up even though the air temperature hasn’t changed. The sun is producing more radiant heat than your body, so you are actually gaining heat from the sun. The reverse is also true. If you are near colder surfaces, your body tries to transfer radiant heat to those surfaces in order to warm them up. If you are in a supermarket in the canned goods aisle and the air temperature is 70F (21C), and all of the items on the shelf are at the same temperature as the air, you feel comfortable. When you turn the corner to the frozen foods aisle, you suddenly feel colder because there is a large mass of cold objects that are drawing the heat radiated from your body away, but the air temperature is still the same as it was only a short distance away. Because about 40% of the heat loss from your body is radiant heat, if you warm up the surfaces in a room to equal that of your body, you can still feel comfortable because you are not losing radiant heat to those cold objects.

Radiant floor heating is installed by circulating warm water in the floor. The most often used method is to put PEX tubing (a polyethylene tubing that is specially processed to have added strength) in a layer of lightweight concrete about 1 1/2 thick poured over the subfloor or in the concrete slab of a basement or a slab on grade house, but the tubing can also be installed in the floor joist cavity under the subfloor. A hot water heating boiler and the appropriate controls are then connected to the system to provide the water temperature needed to heat the house. In some smaller applications the system is connected to a water heater with a heat exchanger (used to separate your potable water from the heating water). The fuel that you use to heat the water natural gas, propane, fuel oil or electricity really doesn’t matter for the system. You can select the fuel that least expensive or most commonly used in your area. There are advantages and disadvantages to the various installation methods and these should be discussed with your installer during the planning stages.

How do I plan for radiant floor heat in my new home?

You should start the planning process as soon as you start to design your home. The builder will need to make adjustments to the construction to accommodate the extra weight and height of the concrete over-pour (if this method is used) and allow for additional space in the mechanical room for the equipment and controls. The earlier you start to plan your radiant floor heating system, the easier it is to incorporate it into your new home.

What kind of flooring materials can we use with a radiant floor heating system?

Radiant floor heating is ideal for any hard surface flooring such as ceramic tile, stone, decorative concrete, vinyl linoleum and tiles, etc. but a properly designed system can also work under hardwoods and carpeting. There are limitations and special considerations for some flooring, especially hardwoods, and it is important that your installer knows all of your finished floor materials so the system can be properly designed to give you the performance and comfort that you expect. There are also special carpet pads that are specifically designed for radiant floor heating systems. Always discuss these options with your installer before selecting your flooring materials.

Once you have gotten the names of the installers that you would like to use, you can start the interview process. A good radiant floor heating system installer will always do a room-by-room heat loss calculation so that the system will work equally well throughout the house. Proper system design is the most important step that can be taken to guarantee that you will get the comfort and efficiency you want. Many installers have a book of pictures and recommendations from past projects and customers that can be used as references. Remember that training and experience have costs. A good installer may not be the least expensive, and you may get what you pay for if you take an unusually low bid.

FAQ — Radiant Heating Systems

What is radiant floor heating and how does it work?

Radiant floor heating systems use your floor as a large radiator, like the big cast iron steam or hot water radiators, but because your floor has so many more square feet of surface area for heat transfer than a radiator, it only needs to be warm to keep your house comfortable. There are three ways to transfer heat: convection (heating the air), conduction (a warm object touches a colder object and transfers heat to it) and radiation (like sunshine). Radiant heating actually uses all three methods to heat your home but mostly works like the sun to warm you. It does not rely on warm air circulating around your house to keep you warm. It is similar to standing outside in the shade on a cold day and then taking a single step into the sunshine. You were cold in the shade, but the sunshine warms you up even though the air temperature hasn’t changed. The sun is producing more radiant heat than your body, so you are actually gaining heat from the sun. The reverse is also true. If you are near colder surfaces, your body tries to transfer radiant heat to those surfaces in order to warm them up. If you are in a supermarket in the canned goods aisle and the air temperature is 70F (21C), and all of the items on the shelf are at the same temperature as the air, you feel comfortable. When you turn the corner to the frozen foods aisle, you suddenly feel colder because there is a large mass of cold objects that are drawing the heat radiated from your body away, but the air temperature is still the same as it was only a short distance away. Because about 40% of the heat loss from your body is radiant heat, if you warm up the surfaces in a room to equal that of your body, you can still feel comfortable because you are not losing radiant heat to those cold objects.

Roth FAQ Radiant Heating Systems

Radiant floor heating is installed by circulating warm water in the floor. The most often used method is to put PEX tubing (a polyethylene tubing that is specially processed to have added strength) in a layer of lightweight concrete about 1 1/2 thick poured over the subfloor or in the concrete slab of a basement or a slab on grade house, but the tubing can also be installed in the floor joist cavity under the subfloor. A hot water heating boiler and the appropriate controls are then connected to the system to provide the water temperature needed to heat the house. In some smaller applications the system is connected to a water heater with a heat exchanger (used to separate your potable water from the heating water). The fuel that you use to heat the water natural gas, propane, fuel oil or electricity really doesn’t matter for the system. You can select the fuel that least expensive or most commonly used in your area. There are advantages and disadvantages to the various installation methods and these should be discussed with your installer during the planning stages.

How do I plan for radiant floor heat in my new home?

You should start the planning process as soon as you start to design your home. The builder will need to make adjustments to the construction to accommodate the extra weight and height of the concrete over-pour (if this method is used) and allow for additional space in the mechanical room for the equipment and controls. The earlier you start to plan your radiant floor heating system, the easier it is to incorporate it into your new home.

What kind of flooring materials can we use with a radiant floor heating system?

Radiant floor heating is ideal for any hard surface flooring such as ceramic tile, stone, decorative concrete, vinyl linoleum and tiles, etc. but a properly designed system can also work under hardwoods and carpeting. There are limitations and special considerations for some flooring, especially hardwoods, and it is important that your installer knows all of your finished floor materials so the system can be properly designed to give you the performance and comfort that you expect. There are also special carpet pads that are specifically designed for radiant floor heating systems. Always discuss these options with your installer before selecting your flooring materials.

Once you have gotten the names of the installers that you would like to use, you can start the interview process. A good radiant floor heating system installer will always do a room-by-room heat loss calculation so that the system will work equally well throughout the house. Proper system design is the most important step that can be taken to guarantee that you will get the comfort and efficiency you want. Many installers have a book of pictures and recommendations from past projects and customers that can be used as references. Remember that training and experience have costs. A good installer may not be the least expensive, and you may get what you pay for if you take an unusually low bid.


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