In most instances, it will reach whatever is set on the thermostat, which can range from 40°F to 104°F. A common setting is 82 degrees, which is usually reached within the hour by most of our systems.
Concrete subfloors can drain some of the energy out of the system and negatively affect the temperatures reached. When installed directly over (grade) concrete floors, systems may be limited to peak temperatures around 75 degrees. You should check our information about Warmup Insulation Boards in order to prevent this issue.
In most other applications on plywood and over living spaces, systems easily reach 82, 85 or 90 degrees. Applications under wood are limited to 85 degrees, and this setting is available in the Warmup programmable thermostat.