FAQ – answers to the most popular questions about radiant floor heating

Some questions come up regularly when people are considering installing or installing a hydronic radiant floor system with water / glycol. So we took the initiative to group them on this page.

What are the benefits of a radiant floor ?

  • Extra comfort from the fact that heat is evenly distributed
  • Aesthetics and great latitude of arrangement of the furniture in the rooms (no apparent heating baseboard)
  • Better air quality because the air is not dried or stirred
  • Energy saving (10% -20%) because the heat is more uniform. Other heating systems tend to heat along the walls and ceiling. We can maintain a slightly lower temperature while being comfortable.
  • More choice of energy source. Water / glycol can be heated by electricity, wood, pellets, natural gas, propane, fuel oil …

Will I need another heating system ?

  • No, you will not need another heating system. If it is well designed a radiant floor system is powerful enough to be your only heating system.
    • If you ever have another source of heating, there is the possibility to control only the temperature of the floor using probes. In this way the two heating systems will not conflict.

Electric (heating wires) or hydronic (water / glycol) ?

  • If you only want to heat a bathroom or ceramic floor in the kitchen, opt for a heating wire system located under the tiles.
  • To heat a basement, a garage or an entire house, opt for a hydronic heated floor, which is more appropriate.

Installation of the piping

What is the concrete thickness required when laying the PEX pipe ?

  • The minimum concrete thickness required is 1-1 / 2 “. This thickness of concrete is found when the pipes are installed upstairs or during renovation where the pipes are placed on an existing slab.
  • Otherwise, in general, the minimum concrete thickness required is 4 “for a basement or garage.
  • Ideally Pex pipes should not be installed deeper than 4 ” into a concrete slab.

How to fix the pipes on the ground before pouring concrete ?

Installation tuyau PEX plancher radiant sur treillis métallique
  • For slabs that need to be insulated, there are two different ways to fix the PEX pipes.
    • The first is with standard insulation, a wire mesh is installed over the insulation and the pipes are fixed on the trellis using tie-wrap
  • The other type of insulation is designed to facilitate installation, Isorad insulation, the pipes fit between the furrows. We recommend using U-shaped clips to secure the pipes in the curves.
  • When pipes are laid on plywood, the use of j-clip is the easiest way to keep the pipes in place.

Is it possible to install radiant floor with water / glycol on the floor ?

Yes no problem, it has three ways to proceed:

  • Install the pipes on the plywood and pour a 1-1 / 2 “concrete slab.
  • Create a subfloor to pass the pipes; here is the composition of the floor: Joists – Reflective Bubble Insulation, Pex Pipes / Wood Fur, Plywood (Plywood)
  • Lay the PEX pipes between the joists and insulate below with reflective bubble insulation and wool.

How far apart should the pipes be?

The recommended distance between the pipes is 9 inches or 12 inches. At Ecosolaris, we recommend installing them at 9 inches so that the temperature of the slab is more uniform.

However, two separate rows of 6 inches along the exterior walls and 5 separate rows of 6 inches along the walls with garage doors or curtain walls are required.

How to calculate the amount of piping required ?

If the pipes are installed at a distance of 12 inches we calculate the total area multiplied by 1.2

example: 500 ft2 x 1.2 = 600 feet of pipes

If the pipes are installed at a distance of 9 inches, we calculate the total area multiplied by 1.5

If the pipes are installed between the joists we calculate the total area multiplied by 2

We often hear about loops and zones, what is the difference between the two ?

A loop is a length of pipe that goes back and forth through the floor

An area is a section of the floor (usually a room) consisting of one or more loops controlled by a thermostat.

What is the maximum length for a loop ?

The maximum length of a loop is 300 feet. Exceeding this length, the temperature difference between the out and the return may be too great, which will make some parts of the floor cooler and therefore less comfortable.

How long after pouring concrete can I turn on the system ?

You have to wait for the concrete to dry naturally for 30 days before filling the pipes and starting the system.

Do I have to fill the pipes with water or glycol ?

You can only use water in your radiant floor system but the glycol will allow you to not worry about possible freezing of the piping in the event of a prolonged power outage (eg ice storm)

What percentage of water and glycol should I use in my radiant floor system ?

  • If you use only water, your system will be subject to freezing at 0 degrees Celsius
  • Using a mixture of 70% water and 30% glycol, your system will be frost-free up to -12 degrees Celsius
  • Using a mixture of 50% water and 50% glycol, your system will be frost-free up to -34 degrees Celsius

Note that liquids are not sensitive to what we call the temperature felt.

Should I use distilled water or can I use tap water ?

Distilled water does not contain minerals and is therefore best to prevent corrosion. On the other hand, when the system is composed of pieces made of quality metals, the difference between distilled water and that of your aqueduct will be very small. However, this is not the case for water from a well.

The glycol we use also contains corrosion inhibitors that will add extra protection.

How to calculate the amount of fluid required by my system ?

The amount of fluid in 1/2 inch pipes is 1 gallon per 100 feet. Thereafter add about 3 gallons for the heating panel and 5 gallons for the water / glycol make up system.

The choice of the boiler

How to calculate the power of the boiler required ?

A new house insulated by building code standards requires approximately 22 Btu / sq. Ft. And an older house may require up to 35 Btu / sq Ft.

In general, we take the area multiplied by 30 Btu and we choose the boiler according to this calculation.

For example: 1000 ft2 x 30 = 30 000Btu = 8 kW

Which boiler to choose, Mini BTH or Mini Ultra ?

The mini BTH is similar to a small 2 gallon hot water tank. If we tell it to heat the water to 100 degrees F, it will heat the tank water to 100F continuously. A circuit breaker installed on the top of the boiler makes it possible to extinguish it in the spring and to reignite it in the fall.

The Mini Ultra boiler is a smart model that only heats the water in its tank when a thermostat requires it, which saves energy. An outdoor temperature sensor is also supplied with the boiler

What is the use of an outdoor temperature sensor ?

By being informed of the variations of the outside temperature thanks to the probe, the boiler can adjust the temperature of the water / glycol of its tank and thus allow to offer more heat to the slab in cold weather and avoids the problems of overheating when the weather becomes milder

What is the power of the circuit breaker required to power the boiler ?

This information can be obtained from your electrician or from the boiler manufacturer’s brochure.

Mini BTH brochure and Mini ULTRA brochure >

Bth Ultra brochure >

And what is the use of a floor sensor ?

A floor sensor takes into consideration the temperature of the concrete slab in order to adjust the room temperature.

It can be used in two ways.

Here are some examples.

The temperature of a garage is usually set according to that of the slab. Thus, the air flow created during the opening of the door will not trigger the start of the system, the temperature of the slab has not necessarily decreased.

For a house, the temperature of the air is taken into account by giving a minimum and a maximum to the concrete slab, in this way if an outside door would remain open when it is very cold, the floor would stop rising when it would reach the maximum temperature of the slab.

Temperature proble sensor for Sinope TH1400ZB and TH1400WF thermostats

How to perform system filling ?

If your system is equipped with a Calefactio make up system, you can use it to fill your pipes with water and glycol. Otherwise you have to use an external pump or contact a professional.

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