THE OUTPUT FROM RADIANT FLOORS IS PROPORTIONAL TO THE DIFFERENCE IN TEMPERATURE BETWEEN THE FLOOR AND THE SOLID OBJECTS THAT SURROUND IT.
IN OTHER WORDS IF YOU ARE COLD COMING INTO A RADIANT HEATED ROOM MORE HEAT WILL
BE DIRECTED TOWARD YOU.
This is an example of placing the tubing under the floor, it shows how even the heat output is.
RADIANT HEAT, HEATS OBJECTS, NOT AIR
OVER OR UNDER?
Some claim that placing the tubing under the floor is less efficient, it is usually someone who is selling something.
Over or under has exactly the same efficiency! Stop and think. Where did the heat go to?
To change the efficiency the heat would have to go somewhere. There are only two places you can change the heating efficiency of a house. Either the heat loss through the structure or the loss up the chimney.
In other words the efficiency of the heating appliance or the heat loss of the construction methods are the only two ways to change the efficiency of your heating system.
AT 85°F. SURFACE TEMPERATURE THE FLOOR CAN PUT OFF 30 BTU PER FOOT OF FLOOR SURFACE. MOST NEW CONSTRUCTION REQUIRES UNDER 20 BTU'S PER FOOT EVEN AT -20°F.
NEW ADVANCED CONSTRUCTION METHODS ARE ATTAINING HEAT LOSSES UNDER 10 BTU'S PER SQ. FT.
SOME FACTS ABOUT RADIANT…
Q: Is radiant more efficient?
A: If you mean will it cost less in fuel cost? The answer is, not always.
If the house is small to medium sized and very well insulated or uses some of the advanced construction methods you will not save with radiant heat.
If the house design is not adjusted to the requirements of radiant heat.
If you use a non-modulating or cast iron boiler you will increase your fuel costs considerably over forced air.
The radiant heated house must be insulated differently to be efficient. A heated floor can lose as much down as up.
Buying the wrong equipment can shorten the useful life of very expensive equipment or damage your home.
Improper or lack of insulation under a slab can cost much more than forced air heating.
Q: What should a radiant system cost?
A: A well designed radiant system with a 96% efficient condensing boiler, stainless steel indirect water heater, Pex tubing, brass manifolds, thermostats and all necessary equipment to install it will generally cost less than $4.00 per Sq. Ft., less than $3.00 for a slab on grade. The larger the home the less the cost of equipment per Sq. Ft. A 5,000 Sq. Ft home will cost less than $3.00 per Sq. Ft. even using the very best equipment. A small addition between 400 to 800 Sq. Ft. normally costs about $500.00 to $1000.00 and in most cases, can use your present water heater. Water heaters start at less than $700.00 for an 87% efficient wall hung modulating combination heater.
A radiant floor heating system, if designed and installed properly, will be the most comfortable and efficient and can often be installed for less than a forced air system. I have thousands of customers to prove it. A properly designed radiant system should use the most efficient heat source that is practical. We design for quality, efficiency, comfort, and simplicity.
GLOSSARY AND TERMINOLOGY
If you see words and expressions that you are not familiar with, just consult this section.
Understanding the meaning of the following phrases will make it easier to understand your heating system options.
BOILER, A boiler is a heating device that is designed to make very hot water (up to 250 degrees F, under pressure) for radiators and baseboards. Many boilers do not work well at lower temperatures and may need expensive controls to make the adjustment. Cast Iron or non-modulating, non-condensing boilers are not suitable for radiant heating systems.
DOMESTIC HOT WATER HEATER, A domestic water heater is engineered to make moderate temperature water. A storage tank is often provided, and additional precautions are taken to prevent corrosion. There is a potential for higher efficiency with a hot water heater because of lower operating temperature and lower exhaust gas temperature, but many low end water heaters do not take advantage of this potential. A few new tank type water heaters are now made for combined heating and hot water production. These tank type, 96% efficient, modulating and condensing heaters with advanced foam insulation are the most efficient radiant floor heat source you can use. They are also the most efficient domestic water heater you can use. They can also be purchased with an internal solar coil to decrease both hot water and heating energy costs. They can be used as either an open or closed system to heat both house and domestic water.
HEAT EXCHANGER, A heat exchanger is a device that exchanges the heat from one fluid to another without a mixing of the fluids. A typical use would be to keep the potable domestic hot water separate from the radiant heating fluid. The stainless steel flat plate heat exchanger is the least expensive and the most efficient.
CLOSED SYSTEM, A closed heating system is one which is closed off from the environment and its heating fluid is not interchanged. The can be a direct system circulating water through the heater directly, or a heating system that is separated from the heater through a heat exchanger.
OPEN SYSTEM, An open system is one that is connected to your incoming water supply system or one in which the heating fluid is replaced often. A domestic hot water heater is an open system because the heated fluid is constantly changed. Open systems require different mechanicals and materials. Open systems are not open to the atmosphere as some believe. All domestic water in your house is considered an open system. This is the same as an direct system.
POTABLE, Potable means water that is safe to drink.
DIRECT SYSTEM, A direct system is one in which the potable hot water in the water heater is used for space heating and domestic hot water for doing dishes, laundry, taking showers, etc. There is no separation between the two. This the same as an open system.
INDIRECT SYSTEM, An indirect system is one in which the heat from the heating unit passes through a heat exchanger before it goes to the in floor tubes. This is the same as a closed system.
TANKLESS HEATERS, These are very small compact water heaters that try to heat the water instantly as the water passes through them. We have had good success using a few of these as a closed or open radiant system for small homes and snowmelt systems.