In fundamental terms, a radiant system circulates heated water or antifreeze through a hidden piping network in order to deliver warm, efficient comfort throughout every room in the building. Also known as hydronic heating, the technology continues to grow in popularity as homeowners look for ways to enhance indoor comfort, lower energy costs and reduce their environmental impact.
Radiant Heating Basics
Conventional furnaces rely on an air duct network to circulate and distribute heated air. Conversely, radiant systems use convection currents to transfer thermal energy, which is based on the principle that warm air rises. Every system depends on a series of flexible piping coils installed underneath the flooring or slab. A mechanical source creates the heat, and a recirculating pump pushes the fluid through the piping network. Heat radiates upward where it mixes and spreads evenly throughout the room. There are two primary hydronic heating platforms:
* Dedicated Systems: In this configuration, a water heater or boiler is used solely to generate the heated water that circulates through the radiant piping grid.
* Dual Purpose Systems: A dual purpose system utilizes a single source to supply heated water for both radiant and domestic hot water usage.
Every hydronic system requires a heating source to ensure the transfer liquid remains saturated with enough thermal energy to satisfy the indoor load. There are three primary methods used to heat the fluid in a radiant system:
* Boilers: Boilers are commonly installed for hydronic heating because of their durable construction, efficiency and quick recovery. The boiler process combines natural gas or fuel oil with air, and the mixture is ignited in a combustion chamber. The resulting hot gas moves through tubes within a specially designed heat exchanger. As the recirculated liquid returns to the boiler, energy is transferred, and the heated water is sent back through the manifold to start the process over again.
* Water Heaters: Conventional water heaters can be effective in radiant heat applications, but it is important to verify the unit’s recovery time is sufficient to service the building on the coldest days. Radiant systems generally operate with a 20 degree temperature differential, so a standard water heater may not be able to transfer the amount of heat necessary to accommodate the flow rate, especially for larger projects.
* Tankless Water Heaters: Instant water heaters can be used for smaller jobs, usually under 1,000 square feet. While tankless models are efficient, they can present problems if the heat loss in the living area does not exceed the minimum BTU output of the device. This situation can cause short cycling and eventual unit overheating.
Hydronic Heating Installation and Cost
Most radiant heating systems utilize ½ inch tubing made from polyethylene or a derivative. There are several different installation methods including snap-on grids, aluminum strips or simply embedding the piping in concrete. The tubing is generally run in concentric circles to ensure the entire floor area will be covered. Once the piping is in place, it can be finished with almost any type of flooring material including tile, hardwood and synthetics. If possible, carpeting should be avoided since the material and underlying pad will serve as an insulator and decrease the effectiveness of the system.
Radiant heating installation costs are generally higher than a traditional forced air system, especially if the contractor is using radiators or convectors. New construction applications are the least expensive because there are no structural impediments to address. It is also important to remember that if air conditioning is required, separate equipment will need to be installed.
Despite the added cost, a hydronic heating system will provide exceptional comfort while eliminating annoying drafts and cold spots. Instead of having hot air blown directly at their faces, occupants are enveloped in a blanket of warmth. Radiant heat is also 30 percent more energy efficient than forced air heating, so a new system will actually pay for itself over time.