Radiant Floor Warming
This is the method where a closed piping system circulates hot water in the floor to maintain a warm temperature that would be comfortable in bare feet. The water is heated with a water heater, often referred to as a boiler (yet it does not boil water) and pumped through a thermostatically controlled valve and tubing that is embedded in the floor. In some cases where the tubing is laid above an existing floor, the thickness of the additional tubing and concrete mix can reduce your floor to ceiling height by as much as 1 ½". This will mean that door frames, doors and baseboards will have to be adjusted. The weight of the concrete and the ceramic, marble or slate tiles that are to be installed adds a considerable amount of weight to the support structure and may require additional supporting to prevent cracking of the new floor or grout lines. This would only apply to renovation projects. New construction would make plans for these factors in advance.
Many new homes with generous construction budgets are heating driveways and walkways to keep them clear of ice and snow in the winter. The cost of gas alone for a single car driveway and a front step could be more that the fuel required to heat the entire home. When laying out the tubing there are several factors to consider such as the spacing of the lines the tube diameter, the mounting base, furniture layout such as cupboards in kitchens, vanities in bathrooms, window locations, boiler size, manifold locations, flow rates and water temperature, thermostat locations and direction the tubing will run so that no overlap occurs. Most of the companies that sell the product will provide the layout, free of charge if you buy their product and if you are at all handy can save big dollars by laying the pipe yourself. Any of the separate temperature zones can circulate water or a mixture of water and glycol (where there is a risk of freezing). Any zones on glycol require a heat exchanger on the boiler to separate water zones from the glycol.
You will still require a ductwork system if you want the same area to have air conditioning, unless your plan is to install a ductless A/C unit. In many new homes the only rooms getting floor warming would be bathrooms, kitchens or hallways that are not being carpeted, but there is no limit to the number of rooms or zones that can be installed.
Floor warming does not have to be done with tubing and hot water. There are electric radiant panels that are a mere 1/16" thick that are able to be custom ordered for any room layout. They will operate on the same principle with a thermostat, but use electrical energy instead of hot water. The adhesive for laying tile or marble can be applied right over the heater mesh saving a lot of thickness and weight.
Either system can be permanently damaged if a handyman or constructor were to drill through the flooring and contact the heater wire or tubing. In some retro-fit installations the tubing can be installed on the underside of the floor boards and woven through the floor joists until the pattern is completed. There would normally be a reflective barrier installed below the tubing to direct the heat in the desired direction. Your standard domestic water heater will not provide sufficient heating capacity to feed even a single room in an average house along with the daily hot water needs so you will be incurring the cost of a tankless water heater with the system.