1

UNDERFLOOR HEATING SYSTEMS LTD

PO BOX 445

WORCESTER

WR3 8YN

TELEPHONE…01905-616 928

FAX………….…01905-616 928

EMAIL…………info@underfloorheatingsystems.co.uk

WEBSITE………www.underfloorheatingsystems.co.uk

2

CONTENTS

1. WHY UNDERFLOOR HEATING?

2. FREE QUOTE DESIGN SERVICE

3. THE PIPE

4. BENEFITS OF UNDERFLOOR HEATING

5. FLOOR CONSTRUCTIONS AND PIPE LAYOUT

5.1 Concrete Floor Constructions

5.2 Timber Suspended Floor Constructions

6. CONTROLS

6.1 Control Partnerships

7. GUIDELINES FOR THE DESIGN AND INSTALLATION OF THE

UNDERFLOOR HEATING SYSTEM

8. CONCLUSIONS

3

1. WHY UNDERFLOOR HEATING?

We now spend an increased amount of time indoors. The majority of the population

now spends at least 22 of every 24 hours in some kind of artificial climate.

Underfloor heating is far from a new concept, it was first used by the Romans. Their

dwellings were constructed with voids through which air, warmed by an open fire,

would pass, thus heating the structure.

Underfloor heating is not a new concept in this country either. In the past electric

heating elements were buried within floor screeds. These were heated over night

using 'cheap rate' electricity. The main fault was the uncontrollability, the building

would over heat during the day but in the evening, when heat is generally required,

no further heat was available. Electric elements are also very expensive to run.

With today's modern multilayer pipes, control systems and high efficiency boilers

the underfloor heating systems of today are extremely comfortable and

controllable. No longer will unsightly radiators take up room space create hot

and cold spots in the house and circulate dust.

Underfloor heating from the whole floor area of the house gently warms the air

above, eliminating cold spots. The warm air convects from the floor surface losing

approximately 2 degrees centigrade at 2.0 meters above the floor, which makes the

system ideal for all ceiling heights.

Independent tests reveal that the most acceptable indoor climate is one in which the

floor temperature ranges between 19-29°C and the air temperature at head level

4

ranges between 20 and 24°C. With radiator or convector heating systems a vertical

temperature gradient is produced; colder at foot level than at the head.

A modern indoor climate surely demands a heating system which will match the

required conditions for human thermal comfort with the principal heating effect

being evenly distributed at ground level and not above head level.

Modern building techniques including improved levels of insulation, double glazing

etc., have improved the U-valve (the measurement for a buildings heat loss)

dramatically for our buildings. Heat source technology has also taken a leap

forward with the introduction of heat pumps, condensing boilers, solar panels, night

storage systems etc. It is worth noting that all these innovations operate at higher

levels of efficiency when linked to a low temperature water distribution system.

Underfloor heating has made it possible to reduce energy consumption by using low

water temperatures. These systems, based on the development of complex and very

high quality plastic pipe, such as the multilayer pipe, now account for over 60% of

some European heating markets.

5

2. FREE QUOTE AND DESIGN SERVICE

Underfloor Heating Systems Ltd offers a free quote service for any project. All we

need is a drawing of the property to be sent to us by post, fax or email. The price will

include the complete package for your underfloor heating system.

When the project is ordered we will also offer a free hand sketch on how to lay the

pipes. An AutoCad drawing of the pipe loops can be ordered for a small extra

charge. But in most cases the hand sketch does the job.

6

3. THE PIPE

Multipipe multi-layer pipe systems now offer the most comprehensive range of

plumbing and heating systems available.

Used extensively throughout Europe, Multilayer pipe is both flexible and formstable. Its

enclosed aluminium pipe ensures that multilayer pipe is 100% oxygen diffusion proof

while maintaining very low expansion rates similar to other metal pipes.

The inner and outer polyethylene pipes prevents scaling and corrosion and its unique

combination of butt-welded aluminium and crosslinked polyethylene ensures that

multilayer pipe is the only full strength plastic alternative to copper. Multilayer pipe

gives the installer the advantages of both metal and plastic, but with the disadvantages of

neither.

Offered with fittings ranging from standard compression to the superb "Press-fit"

system, multilayer pipe brings new and genuine improved standards to installation

techniques. Currently available in 7 sizes, multilayer pipe is now the first genuine pipe for

all applications, be it plumbing, heating, underfloor heating or mains supply.

7

1. Butt-welded aluminium pipe.

2. 100% oxygen-tight and water vapour diffusion tight.

3. Low coefficient of linear expansion.

4. Entirely corrosion-resistant, also against chemicals and electrochemicals.

5. Sound-insulation similar to entirely plastic pipe.

6. Electro-beam crosslinked inner and outer pipe.

7. High resistance to pressure and temperature.

8. Smooth surface, less loss of pressure.

9. Light as plastic piping.

10 Flexible, easy to bend even at low temperature, retains curved shape.

The small bending radius, maximum flexibility and stability of multilayer pipe

make for a rapid, economical and reliable installation.

The multilayer pipe can quickly and easily be used in conventional radiator

installations. Fittings are available to suit system designs or a central manifold

system.

Being an attractive matt white finish the short leg to radiator valves does not require

decorating. The pipe is light weight and supplied in coils, which make

transportation and handling easier.

There are 10 reasons why multilayer pipe is the best available pipe for underfloor heating:

8

There are a number of features and benefits that occur from underfloor heating.

Space & Economics

Every square metre of your home can be fully utilised and the cost for our system is

very similar to a radiator system.

Hygiene

No dust and the underfloor heating will help to reduce house dust mites which is a

benefit to asthma sufferers. Moisture content is too low, to support dust mites.

Aesthetics and Labour saving

You can design your home to suit your needs rather than that of your heating

engineer. Cleaning of the floors is easier and wet floors dry very quickly. Prevents

discolouration of paintwork, peeling of paper etc.

Comfort

Radiant heat will provide the highest comfort levels at an even temperature

throughout.

Silence

Compared to radiator systems, there is no noise. No annoying ticking as pipes

expand in floor voids.

Cost effective

It has been proven that energy saving from 15-40% can be achieved with underfloor

heating.

Ease of control

Small temperature between the floor surface and the air above means the system is

practically self regulating.

4. BENEFITS OF UNDERFLOOR HEATING

9

The Underfloor Heating system can be fitted in both concrete floors and timber

suspended floors. For other floor constructions please contact us and we will

explain the installation procedure. for example we also offer a floating floor solution.

5.1 Concrete Floor Construction

In concrete screeded floors, the screed acts to diffuse the heat across the surface

providing an even temperature at the floor surface.

Depending on the type of building, construction, standards, there are a number of

methods of laying the underfloor heating pipes in concrete floor structures.

The most popular method of installation is as follows:

A concrete slab (or suspended beam and block construction) is laid over a damp

proof membrane. A 20mm thick piece of insulation is fixed to the perimeter

(external) walls, to a height to include the depth of floor insulation and screed.

5. FLOOR CONSTRUCTIONS AND PIPE LAYOUT

10

Whilst the edging insulation may be on show it is covered by wall plastering and

skirting boards.

Floor insulation is laid to the whole area, joints are taped to prevent the ingress of

screed between the insulation boards. The floor is now ready for the underfloor

heating pipework installation.

We recommend you use a 50mm layer of Polyurethane insulation. If there is not

enough space for 50mm insulation, 30mm is recommended. We recommend

Polyurethane as it out performs Polystyrene and its greater density allows use of clip

fittings.

If you use polystyrene insulation (50mm) it is recommended that you install wire

mesh on top of the insulation and tie the pipe to the mesh. For other floor

constructions please contact our technical department.

The underfloor heating system should be installed as below.

11

The pipe is laid at 200-300mm centres dependent upon design. Care must be taken

to protect the pipework whilst installing the screed. Finally the floor finish is laid.

Underfloor heating works well with almost any floor finish; tiles, carpets (use

carpets with a resistance of less than 0.15 m2K/W), timber floors, plastic etc. The

floor coverings and the adhesive must be suitable for the temperatures that

underfloor heating will provide, the maximum temperature they need to resist is

40°C.

Always check with the manufacturer of the floor covering if it can be used for

underfloor heating. Timber floors need to have a moisture content below 10% to

avoid shrinkage. The system must be operated for 21 days with a very low

temperature to dry the screed, then the floor covering can be laid. Also note that the

5.2 Timber Suspended Floors Construction

Timber suspended floors do not conduct heat as efficiently as screeded floors. This

means that the heat output is less.

Some manufacturers use heat emission plates to try to achieve an even temperature

on the floor. This is a very expensive way of installing underfloor heating in timber

suspended floors and at the end of the aluminium plate the temperature is not going

to be very high. Clearly there should be a cheaper solution that works without using

the very expensive aluminium plates. After all, the first floor is usually timber

suspended and on the first floor less heat is usually required. Also note that the first

floor is supplemented by heat from the ground floor.

Our underfloor heating system is very simple and easy to install in timber suspended

floors. The system is based on hundreds of installations that are now working with

total satisfaction.

Between the joists, a 50mm polyurethane insulation board is cut for a tight fit. It is

advisable to use scrap battens from the building site to support the insulation from

below.

screed must be allowed to dry for 6 weeks before the underfloor heating is operated.

12

The pipe is then clipped on the insulation with our special pipe clips. Then the floor

boards are laid on top of the joists. Be careful not to leave too much air space

between the insulation boards and floor boards (25mm is recommended). The joists

need to be notched where needed for pipe runs.

For ground floor timber suspended or buildings 20 years or older we recommend:

To get the timber suspended floor to act as a screeded floor and to give out more

heat, the air gap between the insulation and the floor boards should be filled with a

lightweight screed mix. This infill is normally required for older buildings.

Underfloor Heating Systems Ltd highly recommends the infill for all ground and

first floor applications if the building is not built to current building regulations. The

mix consists of a 10:1 sand/cement or 8:1 'Lytag' lightweight aggregate/cement mix

on top of the insulation, with enough water to hold the mix together. The additional

load imposed on the floor by the mix is approximately 18kg/m2 for sand/cement

mix. Note that the mix is not intended as load bearing, merely as a heat conductor.

The thickness of the mix should be 25mm with the pipe included in it.

13

6. CONTROLS

Controls options

There are many ways of controlling the underfloor heating. First of all, almost any

boiler can be used for underfloor heating. The most energy efficient system is to use

underfloor heating and a condensing boiler. Note, if the underfloor heating system is

going to be used with a combination boiler, always check with the boiler

manufacturer that the flow can be fitted with a secondary pump.

Self regulated

Underfloor heating is self regulating if the building is properly insulated. Heat

output is dependent on the temperature difference between the floor surface and the

room temperature.

For underfloor heating the temperature difference is very small between the floor

surface temperature and the air temperature, even a slight change in room

temperature significantly alters the temperature difference and the underfloor

heating compensates accordingly.

A practical example would be a dining room. First the dining room is completely

empty and then when dinner is served, there are many people in the room giving out

heat. The underfloor heating will automatically reduce the heat output and the warm

water will simply heat another part of the building.

14

Control units

The building can easily be divided into two or three zones. For example a house

with concrete floors on the ground floor and timber suspended floors on the first

floor, could easily be controlled as two zones.

As generally there are two different floor constructions, the underfloor heating

system will need to provide different temperatures and different running times for

the floor constructions. This is best achieved with control units.

Beside each manifold, a two part motorised valve, a pump, a mixing valve and a

programmable room thermostat is installed. We can provide a premade control unit

for each floor or the control unit can easily be made up by the installer.

Note that the control unit is always required when you mix underfloor heating and

radiators in a building.

Manifolds

At the centre of the underfloor heating system is always a manifold. All the

pipework in the building is brought back to a central distribution point, which is

called the manifold.

The flow and return is taken from the manifold back to the heat source of the

building.

15

The manifold comes with many useful items to help during installation of the

underfloor heating system:

• Return manifolds fitted with two-purpose control/balancing valves.

• Unit fully assembled, leak-tested and packed

• Wide range of accessory options.

• Both trunk ends with flat-sealed joints (nut and gasket) for safe, quick and easy

installation.

• Supply and return manifold are each fitted with an isolation valve and a

purge/vent valve assembly.

• Supply manifold fitted with circuit flow meters for accurate and easy balancing

and visual flow indication.

• Minimised depth dimension allows flush-wall enclosed cabinet mounting.

• Control valves are designed to accommodate standard actuators.

16

Mixing valves

High flow, thermostatic blending valve for underfloor heating applications.

These valves are suitable for blending the flow and return to achieve a stable system

temperature, in systems up to 250 sqm. The thermostatic wax element ensures stable

mixed water temperature with quick reaction to supply temperature changes.

Individual room controls

The Underfloor Heating Systems Ltd manifolds are supplied with thermostatic

options. This means basically that on the return manifold, actuators can be mounted.

The actuators act on an on/off basis and they are connected to an air thermostat in

each room. The room thermostats and the actuators are 220-240V.

Underfloor Heating Systems Ltd do not recommend individual controls in the

bathrooms as these rooms often require hot water to circulate through the loops to

dry the floor. One loop should always be manually regulated.

Bathrooms, WC and En-Suites are usually the warmest rooms in a building. The

underfloor heating system does not cover a lot of floor area in a bathroom, so the

system might not provide enough heat. Therefore it is highly advisable to install a

towel rail or a radiator in the bathrooms, to provide extra heat. This can either be

connected to your underfloor heating system, hot water system or electrics.

17

Filling the underfloor heating system

The system should be filled with water and fully vented of air. This can best be

achieved using mains water pressure through the two end caps on the manifold. All

valves should be closed and the flow end cap connected with a hose to mains water,

with the return end cap connected to a hose laid to a waste water point.

One by one the flow and the return valves are opened and closed on loops purging

them of air. When this is completed and the end caps are closed off, the pumps

should be run for five minutes and the air vented again at the end caps until all air is

bled from the system

6.1 Control Partnerships

Underfloor Heating Systems Ltd finds it vital to create partnerships in the HVAC

industry with underfloor heating controls manufacturer. We are proud to say that all

the water controls are supplied by Reliance Water Controls. The pipe is from

Multipipe, one of the largest manufacturers in the world of multilayer pipes.

Both these companies are well reconised in the industry for the excellence in

product and technical backup. Both Reliance Water Controls and Multipipe offers

full technical support and site visits. Using both these companies, Underfloor

Heating Systems Ltd have created the complete Underfloor Heating System that

provides the customer with the highest quality available to a price that are very close

to a radiator system.

18

Introduction

Below we have created a series of answers to a number of design questions we are

frequently asked here at Underfloor Heating Systems Ltd. We hope that these

answers will help you during your project. Any other questions please do not

hesitate to contact our technical department.

• Q) What pipe size shall I use ?

A) Use the 16x2 mm multilayer pipe for the underfloor heating. The Multilayer pipe offers

100 % oxygen diffusion thanks to the aluminium layer.

• Q) How many underfloor Heating Clips should I use ?

A) One clip should be used at every metre of pipe. Note the pipe can also be tied to

mesh on top of the insulation.

• Q) Where do you install Edge insulation.

A) Edge insulation should be installed around all the perimetres of each room. Note

we do not supply the edging strip. This is often installed by the builder. The edge

insulation can be purchased from any builders merchant.

• Q) What is the maximum loop length.

A) The maximum loop length of 100 m must be used in all installations. It is not

advisable to make the loops longer than 100 m. The reason for this is due to the head

pressure from the pump, the pump used is only capable of pressurising water

through 100m of pipe. 100 m of multilayer pipe will cover an area of approximately

25m2. A useful note is to always take the feeder pipes into account from the

manifolds.

7. GUIDELINES FOR THE DESIGN AND INSTALLATION OF

THE UNDERFLOOR HEATING SYSTEM

19

A) The pipe is marked every metre. This makes it very easy to check the length of

each loop. When laying the pipe it is important to mark how long each loop is, this

is to allow the flow gauges to be easily adjusted to the right levels.

• Q) How to design the layout ?

A) The pipe pitch (centres) should be 300 mm for new buildings and for existing

properties 200 mm . If one room is for example 15 m2, try to use all the 100m of

pipe, even if it means to use 200 mm centres. The only consequence of using

200mm centres is that the system will respond quicker. The same applies if a room

of a size 22 m2, try to use 100m of pipe, even if it means to use 300 mm centers.

This clearly shows how flexible and cost effective multilayer pipe is when used in an

underfloor heating installation.

• Q) What type if insulation is to be used ?

A) Use 50mm high density insulation below the pipes and 65 - 75mm of screed on

top of the insulation. All installation work must comply with current Building

Regulations. Note the screed drying time can be 4 to 6 weeks before the underfloor

heating system is operated. The mixing valve needs to be set at minimum

temperature when commissioning the system. Increase the temperature by 2 to 3

degrees everyday. This will avoid the screed cracking.

• Q) What are the best types of floor finishes to suite underfloor heating ?

A) Use carpets with less than 1.5 Tog. Any timber floors need to have a moisture

content less than 10 % to avoid shrinkage. If more the timber should be allowed to

dry naturally.

• Q) What are the lengths of each loop.

20

A) See instruction in the control pack box.

• Q) How do you lay the pipe ?

A) Always lay the pipe in of heat output importance, for example;

1. Cold spots first. (External walls).

2. Inner walls (Internal wall).

3. Follow the hand sketch or the AutoCad layout provided by us.

• Q) What is the distance between pipe and walls ?

A) The pipe distance from walls should be 100 mm.

• Q) What is the maximum temperature differences ?

A) The system is designed to work with a temperature difference between the flow

and the return. The following temperature differences works well with our system:

5,6,7,8,9 and 10°C.

• Q) What size pump shall I use ?

A) It is recommended to use a pump that can deliver a 60 kPa head. For floor areas

larger than 250 square metre use a 80 kPa head. Note we can supply mixing valves

for both pumps.

• Q) What is the water flow temperature ?

A) The water flow temperature will vary between 35-60°C, depending on the heat

losses from the building. If the system operates with thermostatic mixing valves, use

43°C temperature for screeded floors and 55°C temperature for timber suspended

and floating floors.

• Q) How to Install the Control Pack and the Manifold ?

21

A) Maximum heat output from screeded floors is approximately 100 W/m2, the

maximum heat output from timber suspended floor and floating floor is 70 W/m2.

With there being higher standards of insulation in new buildings, average heat

requirements for many buildings are now below 60 W/m2. For small bathrooms it is

standard practice to also install warm water towel rails to give extra heat output as

these areas are usually not very large.

• Q) How does the manifolds work ?

The manifold is supplied with thermostatic option heads on the return and manually

regulated flow gauges on the flow manifold. If individual control is needed,

actuators can be mounted on the return manifold. The flow gauges on the flow

manifold can easily be adjusted by using the key provided and adjusting the nut on

the return manifold before installing the actuators. Normally a 100m loop will have

full flow and half flow will be provided for a 50m loop. The flow rate can be seen

on the return flow meters.

• Q) How do you fill the underfloor heating system ?

A) The system should be filled with water and fully vented of air. This can best be

achieved using mains water pressure through the two end caps on the manifold. All

valves should be closed and the flow end cap connected with a hose to mains water,

with the return end cap connected to a hose laid to waste water point. One by one

flow and return valves are opened and closed on loop purging them of air.

• Q) How is the system tested ?

A) We recommend that your underfloor heating is tested immediately before the

floor is laid. It is recommended to test the underfloor heating system for 24 hours

and using a pressure of 6 bar.

• Q) What is the heat output ?

22

A) If required we can supply you with AutoCad design of the underfloor heating

layout. There will be a small charge for the AutoCad drawing. A hand sketch can

be provided free of charge. Please talk to our technical department regarding costs.

Also we can provide a comprehensive site visits if the client feels this is necessary.

• Q) Is multilayer pipe approved ?

A) Multilayer pipe has a full range of European and British approvals, including DVGW,

KIWA and WRC.

• Q) What are the delivery times ?

A) Delivery of all underfloor heating components is normally 3-5 days from

confirmation of your order, subject to availability.

• Q) What is the working life of multilayer pipe ?

A) Multilayer pipe have one of the highest approvals in the world from the Water

Research Council (WRC); 10 bar pressure and 95°C temperature. Even so the

multilayer pipe is guaranteed for 10 years within leaving the manufacturer for any

damages for which the manufacturer can be blamed. When correctly installed,

multilayer pipe will have a working life in excess of 50 years.

• Q) Is there an AutoCad design service and site visit ?

23

reserves but because of the environmental pollution caused by inefficient

combustion.

Great strides have been made in the development of new heat source technology

from condensing boilers to heat pumps and these innovations also operate at higher

levels of efficiency when used in conjunction with a heating system requiring only

low temperature water.

Clearly, these factors combine to make hydrothermal floor heating the most

attractive option available today for architects, design engineers and end users.

Standards in home comfort, decor and design have never been higher than at

present. The working environment has also changed, there is even legislation

demanding minimum temperature levels throughout the year.

Many of us now spend as many as 22 out of 24 hours in an artificial environment, at

home, at work or travelling between the two. Making sure that this environment is

as healthy and comfortable as possible has become absolutely critical.

Underfloor Heating Systems Ltd recreated the Roman concept of central heating,

using not warm air generated by furnaces stoked by slaves but low temperature

water circulating in a network of special plastic/metal pipes. The method is slightly

different but the concept is the same, to produce a heating system which becomes

part of the structure of the building and offers comfort that no other system can

duplicate. The kind of comfort, in fact, that only comes from warm floors.

Warm feet and a cool head - that is the kind of real environmental comfort that

Underfloor Heating Systems Ltd is purpose designed to provide. It is invisible and

maintenance free, with no space-consuming, ugly radiators. It requires only low

temperature hot water and is ideal for use with modern condensing boilers. Comfort

levels are high, running costs are low.

8. CONCLUSIONS

In recent times we have been forced to look hard at the ways in which we use up the

energy resources of the planet. Not only because fossil based fuels have limited

24

temperatures can actually be reduced by a degree or so and energy consumption in

any well insulated building can be dramatically reduced.

A Underfloor Heating Systems Ltd system has even more to offer - full protection

for safety and long life reliability. Every metre of multilayer pipe carries an aluminium

layer to prevent any oxygen diffusion taking place. Multilayer pipe is 100 % oxygen

diffusion tight. This eliminates any risk of corrosion to metal parts of the system

and means that multilayer pipe can be used in association with radiators in other areas of

the house. It is the peace of mind pipe that is designed to last the life of the building

it serves.

The future of underfloor heating is bright in the UK. The installers and the builders

are starting to understand the value of underfloor heating and the radiator

manufacturers are clearly fighting at the moment to keep their customers.

In Germany for example 90% of the new buildings are installed with underfloor

heating. Scandinavia is also a huge market for underfloor heating. Mostly

underfloor heating in the UK is being installed in houses, factories and leisure

centres. We will soon also see that underfloor heating is being installed in Hotels

and Office buildings, this is a fact in Germany and Scandinavia.

Turning the entire floor area into a giant radiator plane with gentle convection

currents creates the “warm feet, cool head” conditions which research has shown are

ideal for human comfort. Because of this greater comfort effect, design