How and why to install concrete floor radiant heating. Radiant floor heat in
concrete slabs for your home or driveway heating.
There are two types of concrete floor radiant heating systems; one is
using a large thermal mass of a concrete slab floor while the other
lightweight slab over a wooden sub floor.
Concrete
radiant heating is the great option as the main heating system; it is
the cheapest system, it saves the energy, it provides healthier
and comfortable living.
Temperature of the radiant floor heating
in slabs is easy to control, and it is consistent; there are
no drafts and blowing air.
In hydronic heating hot water circulates through the heating pipes so these are known as "wet installations".
Electric
heating can also be used in radiant heating, and it is cost
effective as long as it heats the thick concrete floor, with the
affordable electricity rates of course. Thicker floor
will store the heat longer and make your house comfortable for
hours without any further electrical input.
Radiant heat
in concrete slabs is retained so the open doors or large windows will
not affect the temperature inside your home as much as with forced air
heating systems. Concrete floor with the high density (high R-value)
insulation placed below the slab makes the floor one big radiator.
Installing
concrete floor radiant heating
The best time to install concrete floor heating is when
installing a concrete slab. Why?
Installing a concrete floor radiant heating is not hard DIY
project, but it needs some skills and knowledge. This is also known as
the slab-on-grade installation.
If you are already paying for the
installation of the slab, recommendation is to install the
floor heating also, since the only cost is adding very affordable PEX
tubing, plus labor of course.
In this case, when installing concrete floor heating for the whole
house, there will be no need to buy pipes or
heaters that will occupy your valuable home space.
PEX tubing that is installed inside the concrete slab should be
protected against the damage and freely transport hot water.
During the installation of concrete floor radiant heating
reinforcement wire
mesh should be positioned properly in the slab area and prior to
pouring
concrete. Polyethylene vapor barrier and the insulation are also needed
for efficient heat distribution. PEX tubing is then attached either by
the wire ties or
special clips. The idea is to secure the tubing, and the best will be
to follow the manufacturer instructions.
PEX tubing will be looped inside the concrete floor and the spacing
between the loops will provide more or less heat. Recommendation is to
keep the loops one foot apart to make the bending easier and provide the
unobstructed hot water flow.
Depth inside the concrete slab at which you will lay the PEX tubing will also
determine are you going to use hot water with higher or lower
temperature and how long does it take to heat the floor. Recommended concrete slab thickness should be between 4 and 6 inches.
The location for the most
efficient and safest installation is somewhere in the middle of
the concrete slab and installation should be without any joints. Use the full length of the tubing
whenever you can as there is always a possibility for leakage where the joints are.
With or without joints, new floor radiant heating system should be
checked before concrete is poured, to see are there any defects in the
system. This is done by using the air pressure of 50 psi, and the
tubing must maintain the pressure for 24 h without leaking.
Covering for radiant floor heating
Covering that goes on the cement floor also has a great impact
on the heat transfer. Tile floor, for example, has much better heat
transfer than the carpet. Installing the insulation under the
sub flooring can control the efficiency of the radiant heating.
Recommendation is to buy and install the insulation with the R-value
that is greater than the R-value of the floor covering, so heat can go
up, not below.
Installing
thin-slab floor radiant heating system
Thin-slab concrete floor radiant heating
is a better choice than
the above solution. If you already have an existing concrete floor,
radiant heating system is installed above the
larger slab. On the wooden flooring, you can pour the thin slab of
concrete over the PEX tubing, allowing retrofitting over existing
concrete floor and without significantly raising the floor height.
PEX tubing is secured to the wood sub flooring, not
to the reinforcing wire as in the example above. The height of the
thin-slab of concrete is usually 1.5 inches or 38 mm so the tubing must
be installed tightly to the floor to prevent protrusion the concrete.
Thick concrete slab system due to its high heat capacity is perfect for storing the heat from solar
heating systems, which are having fluctuating heat output. The disadvantage of
thick concrete floor radiant heating systems is their slow thermal
response time.