ENVIRONMENT AND ENERGY
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<< Continued from page 27
Before starting on the design, you should also decide
whether you are going to have a local thermostat in each
room or a centrally controlled system, explains Carter.
Other questions to ask before starting include: is there a
plant room (or space for a plant room) for the hot water
stores? Does the client want a combined hot water and
underfloor system or separate systems? Do you require
sound absorption?
With the systems that Carter installs, there is the option
to either install the pipes in the slab or in the screed.
“Pipes installed in the slab are very difficult to repair and
there could be heat losses from the edges of the slab,”
he explains. “You require less energy to heat a 45mm
screed. The screed needs to float and will expand when
heated. It requires expansion strips between the walls
and the screed.”
“You would need to add 100mm extra to your floor level
to accommodate for a hydronic underfloor system,” he
advises. A minimum of 45mm for the screed and 55mm
for the piping and polystyrene.
Insulation is also key, and you need to be sure whether
there is insulation in the slab. For a new build, this is now
a non-negotiable requirement; however, it may present a
challenge on refurb projects.
He also advises that when installing the piping for an
underfloor hydronic system, the pipes should be tested
under pressure and left while under construction to
ensure that the installer is alerted when any of the pipes
are cut accidentally.
The positioning of the manifold distribution boxes
is crucial, and Carter advises to make sure they are
installed for easy access.
According to Carter, a good rule of thumb to remember
is that there is a 4°C difference between your feet and
what it feels like at your head. “That’s why 16°C at your
feet will feel like 20°C at your head.” That is also why
thermostats should be installed head-height.
Another mistake is when the system is designed with the
wrong pump. “We only use energy-efficient variable speed
pumps, as they last longer,” says Stöhr. “These adjust to
the demand, saving on energy and on wear and tear.”
It is important to choose the right thermostat for your
system as they range from basic to quite intelligent.
There are simple thermostats, normally not very accurate,
and will generally overshoot set temperatures, and then
undershoot. The temperature variance in the room could
be as much as 4–5°C. This influences energy usage. “The
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Heat pumps seem to be the most
cost-effective for smaller systems,
with pellet boilers becoming more
feasible the bigger the system
becomes (generally above 30kW).
more accurate you get the thermostat, the more energy
you will save,” explains Stöhr.
Where possible, the manifold should be centralised to
avoid long supply and return lead pipes.
THE FUTURE / ADVANCEMENTS
When it comes to the actual underfloor system, you
still get out what you put in, and there isn’t much
advancement other than materials becoming thinner
and more durable. How efficient your system is will still
depend on your heat source.
The main thing that has changed recently is the building
regulations and the fact that it is now compulsory for
new builds to have insulation, as mentioned. This has
increased the efficiency of all types of underfloor heating
systems drastically, explains Tewson. Most of your heat
loss is through the floor, second through windows, and
then through the ceiling. “Insulation is preventing the
cold from coming in and heat from being lost through the
floor — which can save you as much as 50% in terms of
energy usage.”
The major developments and energy saving have
come in on the controllers and thermostat side.
Thermostats have become ‘smarter’, says Tewson.
The advanced, intelligent thermostats are set to
your lifestyle and self-adjust accordingly so as to
operate as efficiently and effectively as possible. Even
telling you how much it is costing you in rand to run
a particular system over a particular period. A new
range of Wi-Fi and touch-screen thermostats can be
controlled remotely from anywhere in the home or
around the world.
As with all things, energy efficiency is where most
developments are going. But with heating systems, what
you put in, is what you get out. That is why Schröder
is hopeful of alternative energy solutions in future to
provide a better heat source. “Alternative energy sources
are where the real innovation lies,” he says. “Piping is
piping. Heat sources are the critical thing. Cheap energy
is the future.” PA
February 2019 Volume 24 I Number 12