Rectifying errors caused by design flaws after installation will be costly and complicated. This emphasizes the importance of ensuring that designs are accurate and that the correct-sized system is installed. So, the question is how do you design an underfloor heating system?
Comply with Regulations
Underfloor heating systems have a maximum heat output of 100 W/m2 for hard floors, and 70 W/m2 for wood suspended floors. For any underfloor heating system to function correctly, the property must be built in accordance with current building codes, and no rooms must lose more than the above output.
Consider the Boiler
Underfloor heating offers excellent efficiency when combined with certain boilers, especially condensing models. When using combination boilers, ensure that the boiler can be installed with a secondary pump by checking with the manufacturer.
Choose The Right Screed
Screed is one of the most important design elements to consider. A conventional screed is a sand and cement mixture, sometimes reinforced with glass fibres, applied to a depth of 60mm to 75mm. This serves as a good heat sink but can take at least three hours to warm up and cool down.
Flow screed is a different option. This can be reduced to 40mm, resulting in a much shorter warm-up time of around an hour. Whatever system is chosen, the insulation, clip rail, pipe, and reinforcement will be affected.
Check Your Floor is Compatible
It’s important to check with the floor covering manufacturer to see if your floor is right for underfloor heating. Keep in mind, timber floors must have less than 10% moisture content to avoid shrinkage. The system must run for 21 days at a very cold temperature to dry the screed before the floor covering can be installed. Also, the screed must be left to dry for six weeks before using the underfloor heating.
Calculate Heat Loss
It is critical to evaluate each room individually because they can vary significantly in size, the number of windows, ceiling heights, and other heat loss factors. If you have experience doing this yourself, go ahead, if not, you should always ask for professional help.
Calculating heat loss room by room allows you to see how much heat each room will lose and how much heat the underfloor heating system will need to provide. To calculate heat loss, examine the fabric of each room to determine how much heat is released through the building on its own, including the walls, windows, roof, and floor. In addition, every design considers ventilation loss, which is heat loss caused by air changes in a room.
Keep in Mind
It is worth talking to a tradesperson during the early design stage before considering underfloor heating. They will be able to advise on the floor’s construction. The supplier will also be able to advise on the expected standards for installation.