This test shows what is currently the most popular style of radiant heating in the US - Concrete. It is an old technology that has seen very little change over the last hundred years. Like other tests, Warmboard reaches a surface temperature of 70º F and outputs 10 BTUs per sq ft in just about 20 minutes. The Gypsum Concrete took 2.5 hours to reach 70º F – a long time to wait if you’re cold in the morning - and output only 1 BTU per sq ft in the first 20 minutes.
The striping (the temperature variation across the surface of a panel) only varies by 2.4º F on Warmboard while the Gypsum Concrete is at 5.9º. Warmboard generated 20 BTUs/HR/SF (British Thermal Units per hour per square foot), while the Gypsum Concrete produced 12. This means Warmboard is using the energy you pay for more effectively.
Tubing on the Warmboard panel and in the Gypsum Concrete is 12" apart.
For those installing hardwood over radiant, these results would be more dramatic. A home with gypsum concrete will also require sleepers (not used in our videos). Sleepers are wooden 2x4s located every 12 inches within the concrete pour which allow the hardwood to be nailed down properly. These 2x4s break up the cement space and interrupt the transfer of heat across the surface. The result is much higher striping and much more noticeable temperature differences in the home. Hardwood can be nailed directly to Warmboard, avoiding all these hassles while simplifying the install process.
Both panels were in an environment with a 65º F air temperature. They both also had the same water temperature, 120º F. The insulation over each panel had a R-Value of 2.22.
Note: Temperatures were taken from just above the center of each panel. Striping differences were also gathered from this area. Temperatures from on top of the tube were compared to temperatures at the midpoint between the tubing pattern.