Hydronic Radiant Floor Heating System Explained

Perhaps the nature of the hydronic radiant floor heating system needs to be defined and explained first.

The principles of hydronic radiant floor heat

Hydronics means ‘the use of water as medium to transfer heat or coldness’, and radiant heat is heat transferred by radiation.

The two best examples of hydronic systems are the hot-water or steam radiator you see set up against walls, and the cooling coils of the airconditioner or refrigerator. Both work the same way except for the temperature of the water in the coils.

However, the systems transfer heat by convection, not radiation, when the systems rely on circulating the heated or cooled air in currents to affect the temperature of the room. You can notice this particularly in the drafts of the water radiator is turned on. Radiation, on the other hand, is when heat or coldness is transferred via rays or waves, much like the sun’s method, or that of the desert sand.

How a hydronic radiant system is constructed

In the hydronic radiant floor heating system, the floor is heated through hot (often just warm) water taken from a boiler and circulated in PEX tubes embedded within the flooring materials. The floor materials may be wood, concrete, tiles or mixed gypsum and concrete called gypcrete, also sold in tiles preformed with indentations for the hydronic radiant floor heating system tubing. This last material is particularly appropriate for outdoor applications like the patio or lanai.

In a typical indoor radiant heat, the water tubing is placed between the subfloor and the wood floor slats. The tubing is protected from damage from floor pressure by spaced wood sleepers that create a cavity between the floor layers. There are also pre-grooved panels that are nailed on or beneath the subfloor. The plastic tubing is made of cross-linked polyethylene or PEX, which is generally leak-free, flexible, does not turn brittle over time, is not toxic, and not affected by chemical additives in the concrete mix, by water temperatures or conditions. Heat output is enhanced by a metal or metallic reflector placed under the tubes to reflect heat upwards.

Control of water circulation is performed through a distribution container where the tubings to the different areas of the house are attached. Temperature is controlled by thermostats, often independently for each network. Thus, the ambient temperature for each room may be adjusted as desired.

Check valves and flow control valves refine water distribution, obviating backflow and facilitating temperature control for select and specific areas as well.

Where hydronic radiant floor heat is most usable

There are two situations where the characteristics of hydronic system make them most useful. First it is used often in concrete in the basement. The basement’s concrete floor makes it an excellent radiation mass where temperature can be kept much more stable, especially with its closed space. In the same way, any concrete or tiled ground floors such as patios, garden or yard walkways, garages, and driveways can use hydronic radiant floor heating systems the best way.

With radiant heat installed in your garage and driveway, you need not shovel snow off them. The system melts the snow to give you an obstruction-free path to the street from the garage.

Laminate floors are also good, better than the typical hardwood floor, but the carpets must be appropriately rated for the planned temperatures, and the correct backing should be used. Hydronic radiant floor heating systems are not recommended for vinyl floors.

The best bet if you want to use hardwood flooring for radiant heat is to choose aged hardwoods, or go with bamboo flooring. Aged hardwood floor has been through many different conditions so they are less likely to expand and contract. Bamboo flooring doesn't expand or contract as much as wood either, so this is why it is popular for radiant floor heat. This doesn't mean that you can't use hardwood flooring. You just have to plan wisely.

In terms of location, such hydronic radiant floor heating systems are naturally used in rooms or house areas getting the most human traffic such as bedrooms, living rooms, and kitchens, although many people use the system also in warming up the bathroom.

Now there have been some wonderful innovations with incorporating PEX tubing and radiant heat into a subfloor. You can purchase engineered subfloor like Warmboard which takes place of the regular subflooring. Also, you can strap the PEX tubing underneath the subfloor with aluminum flashing.

Hydronic radiant floor heat isn’t just for concrete anymore. You can use it on any level of the home, whether it is embedded in concrete, built into the subfloor, or strapped to the bottom of a subfloor.

In essence using the hydronic radiant floor heating system to heat up your home indoors and the external places like the garage, pathways and lanais can grant you many benefits that exceed the drawback of high initial investment. Even this may be effectively countered by the savings generated over time, so that eventually the radiant floor heating system becomes more economical than other systems.

So maybe it is time you give it serious thought. The earlier you can save; the more savings you will realize in time. So help yourself: get a hydronic radiant floor heating system as soon as you can.

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Related Articles

Electric Radiant Floor Heat
Radiant Water Heat
Concrete Floor Radiant Heating
Warmboard Subflooring for Hydronic Radiant Heat

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