Heating Systems within the scope of today’s technology, radiant heat is by far the most efficient way to heat a home or office. We have been beta testing for Uponor (Wirsbo) for many years, working closely with them on the leading edge products that are now becoming available. The required water temperatures range from 80 degrees to approximately 140 degrees, depending on the type of installation and degree of heat loss in the room being heated. When designing the systems, we recommend keeping the various water temperature ranges used throughout the radiant system as close as possible, so that the number of different mixing temperatures is reduced. This is possible by using the different installation methods available. When installed in a slab, radiant needs a lower temperature of approximately 80° – 90° as the concrete mass is slow to heat but maintains its heat for many hours. Gypcrete, which is a lightweight material that is poured over the tubing, also maintains the heat but will react much quicker than a slab.
We also have three types of diffusion plates which transfer the heat to the underside of the floor, spreading the heat evenly. There are single groove plates, used mainly for radiant tubing installed in the ceiling and double plates for installing radiant under a floor; which are both lightweight aluminum. Joist Trak plates are also used, which will conduct the heat and transfer it quickly as they are heavier aluminum plates, bringing the tempers within range of the gypcrete in most cases. There is also Quiktrak, a more labor intensive system but very unobtrusive in retrofit work. Quiktrak is installed above the subfloor and utilizes 5/16 tubing instead of ½” it operates on low temperature but, because of the size of the tubing, the loop lengths should not be as long. Lastly, there is joist heating, where the tubing is installed with clips. The clips keep the tubing away from the underside of the floor so that “striping” does not occur. Striping occurs when the tubing is stapled to the underside of the floor in direct contact with the sub floor. The heat is transferred to the floor only where the tubing is so it heats in stripes. When it is installed with clips the insulation is placed in the joist, leaving a 2″ gap from the sub floor and the tubing then heats the space and transfers the heat to the floor evenly. This requires far more energy and should be used in rooms where there is minimal heat loss. The water temperature can go up to 160 and above where more heat is required and is not energy efficient.
Most heating systems operate at maximum temperature all the time, whether they need to or not. If you remember the old giant radiators making the room so hot that the window must be opened to cool it down, letting in the cooler air to cool the room. This is because the radiators are putting more Btu’s into the room than it is losing through infiltration. If you were to cool the water temperature down in the radiators, when it is warmer outdoors, the overheating would not happen and you would achieve the same comfort result as you would in the colder days. This is exactly what we do with our radiant systems.
Mixing of the radiant water temperatures can be done with mixing valves but comfort is better served using variable speed injection with variable speed pumps, as is our trademark. We calculate the actual heat loss of each room so we know how much heat the room needs to replace that loss.
Heat loss is the amount of Btu’s (British thermal units) a room loses due to outside walls, type of insulation, windows, and door to the outside. You will notice the rooms in the center of your home stay warm without heat as they have virtually no heat loss due to the lack of windows, doors or outside walls. Heat loss is traditionally calculated using a 70° indoor temperature with an outdoor temperature of 0°, giving a 70° differential (with the differential being the difference in temperature from inside your home to outside). Of course, this differential will be greatly reduced at an outdoor temperature of 40° or 50°, which is what the outside temperatures are during most of the winter season. This would give us a differential of only 20° or 30° degrees which requires far less energy to make up the difference in temperature and still feel comfortable. So why operate the radiant heating system at its maximum temperature all the time, like the radiator example given above, when instead, it can be varied using much less energy to achieve your desired comfort level.
For more information or any questions you may have, please feel free to contact us!