Electric Radiant Heating Systems

Any electrical conductor that offers resistance to the flow of electricity generates a certain amount of heat. That amount of heat is in direct proportion to the degree of resistance. This method of generating heat is employed in radiant floor heating systems.

The conductor typically used in radiant heating systems is an electric heating cable embedded in the floors, walls, or ceilings. Those electric cables can be installed at the site (as it is the case with a new construction), or may come in the form of prewired, factory-assembled, panel-type units. The heat generated by the cables is transferred to the occupants and surfaces in the room by low-intensity radiation.

Site installed heating cables or prewired and assembled panel units are used in the following types of radiant heating systems:

- radiant ceiling panel systems;

- radiant wall panel systems;

- radiant floor panel systems.
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Advantages of Electric Heating and Cooling

Among the principal advantages of using electric heating and cooling systems are:

• greater safety

• quiet operation

• economy of space

• reduction of drafts

• reduction of outside noise

• uniform temperature

• structural design flexibility

Although the chances of an explosion in gas- or oil-fired heating systems have become very small because of the safety features built into these systems, an explosion simply cannot occur in electric heating system.

A properly installed electric heating and cooling system will last for years without any problems. If a problem occurs, resistance builds up in the line to the fuse or circuit breaker box. At certain point, the fuse will blow or the circuit breaker will trip, which will automatically shut off the electricity before any damage occurs.

Electric heating units are very compact and therefore utilize very little space. In baseboard systems, there is no need for ducts or pipes to carry a heat medium from its source to the space being heated. These factors offer a great degree of structural design flexibility because duct and pipe arrangements do not have to be taken into consideration. In addition, no chimney or flue arrangement is necessary.

If a structure is properly insulated for electric heating and cooling, there is a noticeable reduction of drafts and the degree of outside noise penetration. Moreover, uniform temperatures will prevail.

Finally, an electric heating system is generally quieter than other types because fewer mechanical parts involved in the electric system design. Quiet operation is particularly a characteristic of baseboard-type installations.

What is the difference between low-carbon steel and high-carbon steel?

Low-carbon steel has ≤0.2 percent carbon, can be easily welded, but cannot be hardened.

High-carbon steel has 0.7-2 percent carbon, can be hardened, but cannot be easily welded. Welding results in a change in the structure of the material and redistribution of the carbon and thus affects the strength of steel adversely.

Disadvantages of Electric Heating and Cooling Systems

An electrically heated and cooled structure offers certain disadvantages when compared with other types of heating and cooling systems. When choosing an energy source for heating and cooling system, it is always necessary to weight the advantages and disadvantages of the system and its energy source carefully against the requirements you demand from them.

An electrically heated or cooled structure must be well insulated against heat gain or loss. If it isn’t, the cost of heating or cooling can be extremely high. For that reason, electric systems are rarely installed in existing structures, except in situations where a room is added or a basement is finished.

Electric heating and cooling systems generally have higher operating costs. These energy costs depend on the insulation type of the structure, orientation of the building, the total number of windows (total glass area), the cost of electricity where the structure is located, and the energy use habits of the occupants.

Another disadvantage of electric furnaces is that they are frequently oversized. An oversized electric furnace heats up and cools down too rapidly to maintain acceptable comfort levels in the rooms of the building. However, oversizing is not a problem limited to electric furnaces.

Infiltration Heat Loss

During the heating season, a portion of heat loss is attributed to the infiltration of cooler outside air into the interior of the structure through cracks around doors and windows and other openings. The amount of air entering the structure by infiltration is important in estimating the requirements of the heating system, as well as composition of the air.

A pound of air is composed both from dry air and moisture particles, which are combined so that each one retains individual characteristics. The distinction of these two basic components of air is important, because each involved with a different type of heat; dry air with specific heat, and moisture content with latent heat.

Each heating system must be designed with the capability of warming the cooler infiltrated dry air to the temperature of the air inside the structure. This amount of heat referred to as sensible heat loss and is expressed in Btu/hr.

The most common methods of calculating heat loss by infiltration are:

1) the crack method;

2) the air-change method.

Calculating Heat Loss in Slab Construction

The heat loss for residential and small commercial buildings constructed on a concrete slab at or near grade level is computed on the basis of heat loss per foot of exposed edge.

For example, a concrete slab 20 ft x 25 ft would have an exposed edge of 90 ft (on a perimeter of the exposed edge of a concrete slab). The heat loss depends on the thickness of insulation along the exposed edge of the concrete slab and the outside design temperature range. This information can be obtained from ASHRAE publications.

To calculate a heat loss in Btu/hr, simply multiply the total length of the exposed edge by the heat loss in Btu/hr per lineal foot (lin ft).

Heat loss of a concrete slab = length of the exposed edge x heat loss per lineal foot

For example, a 90 ft exposed edge with 2-in-edge insulation at n outdoor design temperature of 35 degrees F can be calculated as follows:

90 lin ft x 45 Btu/hr/lin ft = 4,050 Btu/hr

Calculating Heat Loss in Basement

Heat loss in basement depends on many different variables. One of them ground temperature, which functions as outdoor design temperature in the heat loss transmission formula. The ground temperatures vary by geographical location.

The usual method for calculating heat loss transmission through basement walls is to view them as being divided into 2 (two) sections. The upper section extends from the frost line to the basement ceiling and includes portions of the wall that are exposed to outdoor air temperatures. The heat loss for the upper section is calculated the same way that other surfaces exposed to the outside temperature are calculated.

The lower section, the wall extending from the frost line to the basement floor and the floor itself can be calculated on the basis of the ground temperature. The ground temperature is substituted for the outside design temperature when calculating heat loss.

Calculating Heat Loss for a Door

It’s not easy to calculate the coefficient of heat transmission (U-value) for a door, because doors vary by size, thickness, and materials.

A fairly accurate rule-of-thumb method of calculating heat loss is to use the U-value for a comparable size single-pane glass window.

If you wish to compute the coefficient of heat transmission for a door, the necessary data can be found in ASHRAE publications. The same source can be used for calculating the coefficient of heat transmission of windows.

Snow melt and retention devices

Snow retention systems on the roof just needed to spring compressed snow and ice blocks are uniformly melted and descended from the roof, scratching her and threatening the inhabitants of the house. Snow retention protects the eaves and gutters of the truncation of the weight of ice blocks.


Snow retention - is an artificial process that protects the roof from scratches and prevents rainwater from gutters to tearing because of the snow weight. Snow retention for roofing, as well as heating of the roof, ensure the safety of residential homes, as a necessary element for the design of its insurance. Modern models of snow melt and snow retention:

  • Tubular
  • Lattice
  • point
  • Plate
Typically they are made of copper, zinc, stainless steel. Tubular snow melt and retention devices intended for roofs of corrugated board, metal, and the seam roof. They are corrosion resistant, coating improves ability. The principle of such snow melt or retention is in portion passing frost and snow between the pipes and the roof. The most ideal location for installation of snow melt and retention devices is considered roof, where the distance from the eaves is no more than a meter.

Lattice snow melt or retention devices set for high roofs of urban buildings, as well as the tiled roofs of private houses. Thus, the detention occurs even small pieces of ice. Snow retention is due to the lattice, which is attached to the edge of the roof. Such snow melt or retention devices mounted with universal supports.

Plastic snow melt or retention devices made of the same material as the usual metal. They are inexpensive, but reliable, used on slopes with an inclination of 30 degrees.

Brazing of flat plate heat exchanger



Brazing is well-suited to making leak-tight tubing joints like this because once everything gets hot enough the filler metal (the thin rod) melts it runs all the way around the joint.