1.
What is underfloor heating?
Warm
water is circulated through a series of pipes laid in the floor
at the time of construction. These pipes form a continuous loop
between two distribution manifolds. Heat is transferred from
the pipes to a thermal conducting medium, which is usually concrete.
The concrete is in contact with the floor surface, forming a
continuous thermal path. Heat is given off from the floor surface
into the room in the form of radiant heat (around 50-60%) with
the remainder being made up by conduction and convection. Each
room has its own circuit and is individually controlled by a
room thermostat linked to an actuator at the manifold, putting
the heat exactly where you want it.
Back to top
2.
I haven't heard much about underfloor heating, is it new?
Underfloor
heating first came to the UK over 2000 years ago. The Romans
brought the basic technology with them and used underfloor heating
in their villas. They used a system of hot air ducts which passed
under the floor from one side of the building to the other.
The rooms which needed to be hottest were situated nearest to
the heat source while cooler rooms were furthest away. Modern
underfloor heating is relatively new in this country, but has
been used extensively in Europe since the '70s. Back
to top
3.
Why is underfloor heating better than a radiator system?
The
most obvious reason is that there are no ugly radiators taking
up valuable floor space. Your floor space costs you a lot of
money, and if you can't use it because there's a radiator on
the wall, then the cost of that floor space should be added
to what it has cost you to have a radiator system. We say that
a radiator takes up as much room as a hippopotamus and is about
as attractive to look at! Not having radiators gives you greater
freedom to decorate and furnish the rooms as you please, which
is ideal for today's modern homes that often include full height
glass, and perhaps double height ceilings. For even more reasons
please visit our benefits
page.
Back to top
4.
Is
it expensive?
Not
for what you get. The benefits
far outweigh the wee bit extra it costs to have underfloor heating
rather than ugly radiators, and it goes on paying for itself
for all the years the building exists by saving you money on
your fuel bills. Many people think nothing of spending £10,000
- £15,000 on a fitted kitchen and change it 10 years later,
only to pay the same or more for a new one. Once your heating
system is installed, which costs only a fraction of the cost
of a kitchen, it's in for the life of the building and you just
can't change it later. Remember, when comparing the price of
installing underfloor heating against radiators, the additional
cost to have underfloor heating is only the difference between
the two prices. Also, you'll be paying a lot of money for the
floor space that hippos take up in each room - floor space that
you won't be able to use for anything else. Add all this up
and you're into £1000s for the dubious privilege of having
radiators, before you even buy them and pay someone to fit them.
We will be happy to provide you with a free no obligation quote
for underfloor heating, after receiving a copy of your floor
plans, elevations, and a completed quote
questionnaire. Please see quotation
information page for details of what we need to calculate
your quote. Back to top
5.
What
about running costs?
Underfloor
heating can be up to 20% cheaper to run than a radiator system
when used with a high efficiency condensing boiler. This level
of saving can easily be maintained and may even be exceeded.
If you're considering it for a large building like an office
block or factory, then it could be up to 40% cheaper to run.
The trick is to avoid regular changes in time and temperature
demands by keeping the house at a constant temperature, thereby
reducing fuel use. Couple it with renewable devices such as
a heat pump, and you're quids in.
See our case studies for a fabulous example of how little underfloor
heating with a heat pump can cost you to run.
Back to top
6.
What
fuel does underfloor heating run on?
You
can use any kind of fuel to warm the water that circulates through
the underfloor heating pipes. The most popular choices
are oil or gas in the form of a condensing boiler. These are
at their most efficient while working at the lower temperatures
required by the underfloor heating. But underfloor heating will
also run with a heat
pump, solar panels, log burner with back boiler,
or a combination of heat sources, but these would generally
need to be linked through a thermal store. Heat pumps and underfloor
heating are a match made in heaven because the heat pump provides
water at exactly the correct temperature for the underfloor
heating. Back to top
7.
Can
I use an alternative heat source such as a heat pump or solar
panels?
Yes.
Because the system operates on low temperatures (typically between
30C and 50C) it is ideal for connecting to alternative heat
sources such as a heat pump, solar
panels, a heat recovery system, or wood/pellet boiler. Using
a thermal store, these systems can be used in any combination
to supplement the output from your boiler and save you even
more of your fuel costs. Bear in mind that solar panels are
best used for domestic hot water rather than the heating, because
when the demand for heating is highest, the output from the
solar panels is at its lowest.
Back to top
8.
What
if it leaks?
The
system should not leak! The Pex pipe is made to the highest
standards and is guaranteed
for fifty years. The pipe has been in production and development
since the 70s. It can withstand a constant temperature of 95C
at 6 Bar (85 psi). Depending on your floor construction, the
system normally operates at temperatures between 30 - 60C and
usually only between 1 and 2 Bar (28 psi). If the pipe is damaged,
usually during the construction phase, it is quite acceptable
to make a local repair using compression couplings, and make
a note of where this is for future reference. Back
to top
9.
What
about servicing?
Servicing
is easy... because, well basically, none is required. Once the
Pex pipe has been embedded in the floor, there is never any
need to see it again. It should outlive the house. The only
servicing required is the normal scheduled maintenance required
by the boiler. It may occasionally be necessary to service or
inspect moving parts such as pumps and valves to ensure their
continued operation.
Back to top
10.
Is
underfloor heating controllable?
Oh
yes. Each room has its own individual circuit, or perhaps more
in open plan area. Each room has its own thermostat which is
linked to a motorised actuator on the manifold. Adjusting the
thermostat will allow the actuator to control the flow to that
circuit. In addition, you could have an intelligent control
system that includes weather compensation. This automatically
monitors the outside temperature and maintains the system at
your preferred temperature all the time. Ask a person who has
the intelligent control system and they'll tell you that they
never know when their heating is on or off because they never
have to adjust it; their rooms are always at a comfortable temperature.
You don't have to think about adjusting your settings once it
has been set up and you've settled on your ideal time and temperature
settings for your lifestyle. The intelligent control system
allows you to have time and temperature control of each individual
room. It also has the optional facility to manage your domestic
hot water requirements. The system can be used in conjunction
with a modem that will allow you to control the system from
a remote location, for example if you've been away on holiday
or you only use the house at weekends. Back
to top
11.
Is
it easy to install?
Installing
underfloor heating pipes is not rocket science and anyone with
good DIY skills should have little problem installing the circuits,
but if you're not confident, for peace of mind we would suggest
that it should be installed by a professional installer, or
at least your plumber. Underfloor heating is easier to install
than a radiator system and the pipes are installed in continuous
loops, which start and end at a central manifold. A technical
manual with installation instructions is given with each system
and advice by phone is always available for those wishing to
install the system themselves.
Back to top
12.
What type of concrete screed should I use?
Your
builder will generally lay a screed that he is used to working
with, but sometimes they ask us what the mixture should be.
It is generally best to keep the screed workable but with some
inherent strength. Small aggregate chippings (10mm) can be used
in conjunction with very sharp, gritty sand. The consistency
should be easily trowelable in order to achieve a finish that
is as smooth and level as possible. Back
to top
13. Can I use a pouring screed?
An
anhydrite gypsum based pouring screed dramatically reduces the
time it takes to complete the screeding process. This type of
screed is very mechanically and thermally stable and not prone
to expansion and contraction in the same was as a traditional
concrete mixture, which is more prone to cracking. The pouring
process only takes a few hours, or less, depending on the size
of your project, and can be walked on after 24 hours. The total
thickness of pouring screed can also be reduced to around 50mm.
Although slightly more expensive, the labour element is much
less than mixing and laying traditional concrete would be, and
the final finish is absolutely level so is perfect for tiling
directly onto. Our customers who have used a pouring screed
have all been glad that they did.
Back to top
14.
I want to have hardwood floors. Will underfloor heating
damage the wood?
No.
At least not if you follow the manufacturer's guidelines. Almost
all hardwood flooring and wood laminates are suitable for underfloor
heating, but should always be laid in accordance with the manufacturer's
instructions. It is good practise to first lay the wood out
loose and allow it to acclimatise to the room in which it is
to be finally laid. Concrete floors should be tested for moisture
content prior to laying the wood. Once laid, underfloor heating
is actually very good for wooden floors because it maintains
a constant even temperature over the surface of the floor, eliminating
hot spots close to radiators. The surface temperature of the
floor should be maintained below the hardwood manufacturer's
threshold. Most hardwood manufacturers recommend that the surface
temperature of a hardwood floor is limited to a max of 27 deg
C. This can be achieved by fitting a floor sensor into the screed
along with the floor pipes. If you're considering using wood
on a concrete floor ask us about a simple test you can do to
check that the concrete is completely dry before you lay your
wood. Engineered hardwood is more thermally stable and is more
likely to be able to tolerate somewhat higher surface temperatures.
If you intend putting large thick rugs on top of your hardwood
flooring we would suggest that you reconsider. If you put a
heavy rug on top of a hardwood floor it will restrict the output
from the floor and increase the surface temperature of the wood
beneath the rug. You should be aware that this could damage
the wood, and will certainly impede the heat output from your
floor. Try it by lifting a rug, or even just a cushion, after
it's been lying on the floor for a while and it will be warm
and toasty underneath because the rug or cushion has insulated
the floor. Back to top
15.
Can I have carpets on my floors?
Yes.
We used to say that your carpet and underlay should have no
more than a 1.5 tog rating, but tests have shown that a sensible
choice of carpet makes no appreciable difference to the output
of an underfloor heating system. A lightweight carpet with short
pile on a light or medium weight underlay is normally sufficient.
Underfloor heating can be used in conjunction with any floor
covering, but you should bear in mind that carpets act as an
insulator so the output from the floor will be slightly reduced.
We can provide a quotation with guaranteed room temperatures
based on your preferred floor coverings as long as you tell
us about them when requesting a quotation. You can put carpet
on top of a hardwood floor but why would you want to? Please
read the section on hardwood above before deciding to do so.
Back to top
16.
Can I still fit underfloor heating if my build is at an advanced
stage?
Yes
this can be done, depending on your floor construction and just
how advanced your project is. For suspended
timber floors where your floor levels are already
set, preventing you from laying the pipes on top of your joists,
you can install the pipes between the joists instead. This requires
a bit more preparation work from your joiner because he will
have to install trays between the joists onto which the pipes
are attached. When it comes to laying the pipe our team will
notch the joists to allow the pipe to pass between. There are
potentially serious implications when notching joists, and we
always insist that you consult a structural engineer or architect
before we install a system using this method. Please see the
between
the joists diagram for more detailed information.
For concrete floors it's probably obvious that you can only
install the pipes if the concrete has not yet been poured, otherwise
it will involve raising your final floor level. The best floor
construction is a slab
plus screed floor, where the pipes are laid on rigid insulation,
and you are only heating the top 60 - 75mm of concrete. Back
to top
17.
Can I have underfloor heating throughout my home?
Of
course. There are no restrictions on where the system can be
used. It's a boon in bedrooms and bathrooms because of furniture,
and bathroom fittings placement. Personally speaking, walking
on warm bathroom tiles in the morning still reminds me of walking
on a warm sandy beach.
Back to top
18.
Can I fit underfloor heating in my existing home?
This
is a very difficult question and the answer depends on your
circumstances and the degree of disruption you are prepared
to endure. Fitting underfloor heating involves major upheaval
in an existing home and is usually impractical because it requires
the complete rebuilding of your floors. We do not normally recommend
that you pursue this option although if you are determined enough,
and have pockets deep enough, then anything is possible. Underfloor
heating is normally installed in new builds or major renovation
projects where the floors are being newly constructed anyway.
Back to top
19.
Can I have underfloor heating in an extension or conservatory?
Yes.
Underfloor heating can be used in conjunction with an existing
radiator system as long as you can access the hot water from
your boiler upstream of the radiator circuit and its valves,
pumps and other controls. See this diagram
for more detail. Underfloor heating is ideal for use in conservatories
where lack of wall space makes radiators impractical.
Also, you don't end up heating the roof of your conservatory,
the heat remains where you are. Installing underfloor heating
in a conservatory or sun room will possibly give you more year-round
use of a conservatory than a radiator system.
Back to top
20.
Why is underfloor heating controlled separately from my radiator
system?
The
two systems have to run independently of each other because
they operate at different times and temperatures. Radiators
are usually programmed to come on twice per day and heat up
from cold each time, whereas underfloor heating is continuously
'active.' Contrary to what you might think, this in fact saves
money on your fuel bills because underfloor heating operates
at a much lower temperature. Once the floor has warmed up it
takes a very small amount of energy to keep it warm; a bit like
a pan of water on the cooker. It takes a while to heat it to
boiling, but once it's boiling you can turn it down to a simmer
and it will only take a small amount of heat to bring it back
up to temperature. Click here
to see how radiator systems and underfloor heating systems are
plumbed together. Back to top
21.
Don't I need metal plates to transfer the heat?
No.
Metal diffusion plates, usually aluminium, are sometimes used
to transfer the heat from the pipes to the underside of the
floor surface in a timber joisted floor. They typically have
pre-formed channels into which the pipe is fitted. The plates
are fitted between the joists. The difficulty arises if the
joist spacing is in some way irregular and the plates cannot
easily be fitted between them. They are also impossible to fit
into areas where the pipe needs to pass from the manifold location
to each of the individual rooms. Furthermore, using heat transfer
plates will typically double the cost of the underfloor heating
materials. There are more effective, much easier, and certainly
much cheaper ways of achieving satisfactory heat transfer. Back
to top
22.
Does the underfloor heating pipe have an aluminium core?
No,
the pipe we use does not. Pipe with an aluminium core, or Alpex,
was originally developed for use with higher temperature domestic
hot water plumbing and radiators. Some underfloor heating supply
companies use Alpex, but it can be difficult to work with because
it is not easy to reshape if you get it wrong and need to reposition
the pipe. Also, Alpex is more expensive than normal plastic
Pex pipe. Some people believe that using Alpex pipe will protect
the pipe from accidental damage, but Alpex is just as easy to
put a nail through as any other.
Back to top
