How Radiant Heating Systems Work
Materials are made up of atoms in motions, as heat energy is absorbed by an object, the vibrational motion of its atoms increases. Temperature or heat is a measurement of the severity of this vibration motion. Now, you ask, what does this have to do with the heating system that I want to install in my house? Well? I’ll get to that, hold on.
These moving atoms create an electromagnetic field; hot objects have a larger electromagnetic field due to the greater motion of the atoms. When the electromagnetic field reaches a cooler object it causes the atoms in that object to increase its vibration and thus its temperature. When you install a radiant system, the floor (if you install the system in your floor) will be warmer than the rest of the room and it will radiate electromagnetic waves out from it and heat the objects in the path of these waves-people, tables, chairs and so on. It will not heat the air, although the air will heat up some due to convection from the objects that were heated by radiation. Energy in the form of electromagnetic waves, transfers from hot to cold without the need for a medium. The radiant energy of the sun travels 93 million miles through space before it reaches earth. Here is an example; if you stepped from a shaded area on a cold day and turned towards the sun, your face would feel warm while your back would remain cold. Moments before you stepped into that space, the rays of the sun were passing through it, but they did not warm up this space; if they had then your back would have felt warm also.
The Advantage of Radiant Heat
Radiant heating systems run generally 25 to 30% lower heating costs, because there is little heating of air and more heating of objects. This leads you to use a lower thermostat setting. Because the air is not heated, there is less pooling of warm air in the high areas of rooms and less transfer of heat through the ceilings and walls
Radiant systems are completely concealed in either the floor, walls, or ceilings and thus there is nothing to hamper the furniture arrangement or the decorative plans. Because the air is not heated there is little thermal currents to cause dirt and dust on the floors to be picked up and deposited on the walls and furniture. Radiant heating also has a better comfort balance because radiation is a major form of body heat loss caused by surrounding objects with a lower temperature. With a radiant system, these objects will be warmer and thus reduce the body heat loss through radiation. Because the excessively high room air temperatures of a forced air system are not needed, feelings of stuffiness and dryness may be reduced.
There is little stratification in a radiant-heated area and because of this there are fewer drafts. Radiant systems have the ability to control the temperature in each room much better than in a forced air system. Air moving over a person’s body (as with a forced air system) will actually cool it, with a radiant system this does not occur because there is very little moving air. The source of heat for the system can be propane, wood, oil, electric, geothermal and even solar (solar will generally need a second source) or any combination of these systems.
Recently, there have been some very good controls come on to the market that will do things like monitor each zone so that every zone operates independently and heating throughout the house can be varied according to the settings of each thermostat. Also, the outside air temperature can be monitored so that the system water temperature can be raised or lowered according to need, which means further fuel savings. If the boiler is used to also heat the domestic hot water, certain control models will give you the option of having hot water priority so that you can have an almost limitless supply of hot water (There is a default so that the house won’t get too cold.) Things like automatic pump or zone valve actuation during the non-heating season to ensure that equipment does not lock up during unused times, night set back to lower the temperature at night and further reduce heating costs, boiler protection from thermal shock due to cold water entering a hot boiler, are some of the endless possibilities. Radiant systems can be as complex or as simple as you want, depending on what you want out of your heating system.
Cost of a Radiant System
Ever been to a house that has radiant heating? If you have, it was probably pointed out to you because the owners liked it so much that they wanted to tell you. Have you ever been to a house and had the owners come to you and say “what a great heat this forced air system is”? Probably not. People love radiant systems-they are quiet, produce a comfortable atmosphere, and with all the new technology out there these systems can be a great source of heat that will last for a long time to come. Another advantage is that radiant heat is a great selling feature for a new home. Radiant systems will pay back their initial higher cost over a period of time due to the lower cost of fuel bills. They will also pay for themselves in comfort. Why build a new home with all the features that you want, only to be uncomfortable due to a poor heating system? The heating system is one of the main things that make a home comfortable.
A radiant system does not need to be only installed in high-end homes. They can be also installed in small homes where only there are fewer zones and thus less expense. They will be just as comfortable.
The price of a radiant system can vary as greatly as the price of building a new home can. For example, a 1000 square foot home can have a radiant system installed for as little as $4,500 using an electric boiler, one zone and one pump. This same building could easily reach $10,000 using a more complex system. If you are interested in using a radiant system meet with a contractor, go over your plans, and work out a system that will meet your needs. A good contractor will take the time to explain the options and how everything in the system works. If he can’t or won’t, maybe you have the wrong contractor. A good radiant system should run trouble free for years if it is installed by a contractor who is familiar with radiant heating and their related controls. Ask questions, ask for references, and remember that the lowest bid may not always be the best deal.
Rick de Haan, Kootenay Boiler Works