Comparison of Hydronic and Electric Radiant Floor Heating Systems


Applications of radiant heating systems

Both hydronic and electric warm floor heating systems are very common and popular methods for heating floors in kitchens, bathrooms, showers and even the entire houses. While different fundamentally, these systems essentially represent the same type of energy used to heat the floor and create a warm, comforting and inviting home atmosphere. This energy is called “radiant heat”.
The optimal flooring type for a radiant heating system is the one with greater thermal conductivity (heat transfer) and lower R value (resistance to heat transfer). Flooring such as tile, stone, granite and marble are best suited in warm floor applications. Hardwood and laminate are also considered suitable, although they have lower thermal conductivity than ceramic and stone tile flooring. Carpet is worst suited for radiant floors, as it has an inherently high R value and low heat transfer and heat distribution properties.
 

Source of heat

In an electric heat system, a specially designed cable emits heat when powered and this heat is transferred to the flooring underneath which the cable is installed. The heated floor, in turn, acts as a single large radiator and heats up the surrounding environment, whether a kitchen, shower, or a bathroom tile floor. Electric floor heating cable is supplied either on spools or pre-spaced and secured onto fiberglass mats for faster and easier installation.

Hydronic – PEX tubing (cross-linked polyethylene) carries hot water to the heated area and transfers heat to the flooring and consequentially to the surrounding environment. PEX tubing generally comes in rolls of 250, 300 or 500 ft depending on the diameter.
While using the same principle, an electric underfloor heating system may actually heat the floors quicker simply because there’s no water heating and circulation is involved.
 

Limitations on heated floor size

Electric heating systems – size of the heated area which can be controlled using a single thermostat is limited to 150 square feet for 120V heating systems and 300 square feet for 240V systems respectively. This restriction is caused by the current load limits present on the thermostat which controls the system. In particular, Honeywell floor sensing thermostats sold at HeatTechProducts.com are limited to a total load of 15 Amps per unit. Since 120V HeatTech floor heating system draws 1 Ampere per 10 sq. feet of heated space (at 3” standard cable spacing), it is limited to 15A/(1A/10sqft) = 150 sqft. Similarly, 240V systems draw 0.5A per 10 sq. ft and therefore allow heating floors up to 15A/(0.5A/10sqft) = 300 sqft total.
To overcome the above limitations, HeatTechProducts.com offers specially designed and affordable controls which allow to extend the heating capabilities to 1,500 sqft for 120V systems and 3,000 sqft for 240V systems respectively. Inquire with our Tech Support for details.
 

Hydronics heating systems – unlike electric, hydronic floor heat systems carry the advantage of not being limited to a particular size area. As long as the length of PEX tubing is within acceptable range and system is capable of providing sufficient amounts of hot water, a hydronic system can be utilized for any size area – from a compact bathroom to a large commercial warehouse.
 

Architectural impact

From an architectural point of view, electric radiant heat systems have the least impact, since heating cable thickness is only 1/8” (compared to 5/8” outside diameter of 1/2” PEX tubing). As a result, electric in-floor heating systems do not raise the finished flooring and do not increase the weight of the floor so as to require special considerations for structural load. If tile floor heating is desired only in a kitchen, it can be implemented at any time with minimum or none visible or structural effects.

Hydronic systems, on the other hand, requires careful considerations about the height of the finished floor and added load on the existing structure. In some cases, bearing beams may have to be reinforced and bearing columns added to support the extra weight.
 

Efficiency of hydronic and electric systems

Put it simply, electrical floor heating systems are designed to convert nearly 100% of the electrical energy exclusively for heating purposes. The efficiency of a hydronic radiant system inevitably depends on the efficiency of the boiler (or other heat source), insulation, length of tubing runs as well as properly sized and selected components (such as circulator pumps, air eliminators, etc.).
 

Summary

When heating a single or multiple rooms with up to 300 sqft each, an electric system is a clear winner, with lower or comparable material costs, no maintenance involved, easy installation and no visual or architectural impact.
When heating rooms over 300sqft or considering a whole house floor heating system, obtaining an estimate from your contractor and supplier of choice would be necessary to make a final decision.

To obtain a free project quote from HeatTechProducts.com, visit our Quotes Page and complete the Quote Request Form.

Read more about the advantages of HeatTech over hydronic and air heating systems.