Underfloor Heating

All about warm water underfloor heating

You can find everything that you need to know about underfloor heating.

Gas, oil, solid fuel, or electric-resistance hot-water condensing combi boilers can be used as the source of heat for any underfloor heating system, as can a number of other technologies. Condensing boilers and ground-coupled heat pumps are particularly well-suited as the operation of underfloor heating systems allows them to operate in their most efficient manner.



The Advantages of Underfloor Heating

Underfloor heating offers several advantages over conventional radiator heating. With underfloor heating there is a little air circulation and the rooms are evenly heated. It is an energy efficient way to heat up the whole house. The heat comes from the floor and not from above. Therefore you can often turn the thermostat 1-2 degrees lower for the same comfort feeling. As its name says the underfloor heating is under the floor and invisible for the eyes leaving the walls free.

  • Even warmth and comfort throughout your home or business premises without dust circulation (excellent for asthmatics and people with allergies)
  • Environmentally friendly, especially when used with condensing boilers
  • More flexible - rooms can be independently controlled via individual programable thermostats
  • Practically lasting lifetime of house
  • Complete freedom for innovative interior design
  • Heating mats are invisibly laid under the floor
  • Timesaving - due to ease and speed of installation


Buy warm water underfloor heating kits.


Underfloor Heating Pipe

Advantages of underfloor heating pipe.

HPW delivers DOWLEX 2344 E PE-RT (PolyEthylene of Raised Temperature) pipes. This pipe is fabricated with five layers. The DOWLEX pipes prevent oxygen passing according to DIN 4726 and can be used for water temperatures up to 95 degrees C and a pressure of 6 bar. In addition, pipes also have KOMO certification. It is important to eliminate oxygen from the pipes to prevent corrosion. HPW can deliver pipe with a diameter of 16 x 2.0 in rolls of 90,120,200,500 and 600 metre lengths.

To lay the pipes is easier than ever before with the pipe roll holder trolley which is available at HPW.

UFH can be installed in several different ways. In the first method the concrete floor is covered with pipesulation board. This makes laying the pipe easy and quick. That is than covered with 50 – 75mm of screed. Above this the floor is finished.

The second method is to lay the pipe between joists. First insulation is installed between the joist at a distance of about 30mm below the floorboards. Then pipecliprails are clipped to the insulation. The pipe is than pressed into the cliprails. Floorboards go on top of it all.

The HPW uses specific patterns to lay the pipes. When pipesulation boards are used then the pipes are laid in a snaleshell pattern with a centre-to-centre distance of 100mm. By using 100mm distance we double the output capacity. By using the snaleshell pattern we equally heat up the room. Not like most other makes who lay the pipe going from the left to the right of the room which results in the room heating from left to right.

Second pattern, the combined meander pattern is used between joists. Again at a centre-to-centre distance of 100mm. The combined meander pattern also heats the room gradually.



The Correct Underfloor Heating Pipe Layout

The correct pattern ensures even temperatures throughout the floor area. When the flow and return pipes are situated next to each other, the floor is warmed up equally. This decreases the chances of cracks in the floor tremendously. The water runs through the pipes and releases its heat. The cooled water runs back to the manifold. Our design and planning is like no other in as much pipe centres are all 10cm. This innovative pattern enables lower water temperature circulation throughout the system. Max flow temp needed 35-40°C. This technology gives the most economic floor heating system, which is able to cut your gas bill.

How to lay correctly down the underfloor heating pipe.

When using the pipesulation boards start laying the first board in the corner of the room with both overlaps touching walls. Remember to allow enough pipe to connect from the room to the manifold. In the middle of the circuit it is important to bend the pipe in a “light bulb” shape to avoid kinking if 100mm centres are used.

Please remember that it is very important that the pipe is laid as directed, the pipe layout is adhered to and the pipe is free from kinks.



The Manifold

The Heating and Plumbing Warehouse uses a unique all in one composite (LTV) manifolds. No need to assemble pump, thermostats or valves. Everything is made ready to go on the wall. Most of the manifold models fit in a cupboard. Larger models will go under the staircase or in a utility room.

The manifolds are available up to 16 ports. They are designed to pump around the water in underfloor heating installations. This series of manifolds are made of a special composite which allows it to be used in low temperature systems.

The underfloor heating manifold is simply plumbed in as a radiator, 15mm pipe flow and return ( 22mm for manifolds larger then 8 ports).

For small areas up to 5m² we can supply the Return Temperature Limiter Control Set & Fittings.

More details about the underfloor heating manifold.

The manifold should be sited as near to the circuits as possible and fixed vertically to the wall with the bottom section approximately 300mm above floor level.

Each port on the manifold can have a maximum of 120m of pipe connected which covers an area of 12m² with the pipe centre distance of 100mm.

For more information please see our underfloor heating manual: Download Manual (18.88 MB)



Connecting the pipe to the manifold

Connecting the pipe together using the Euroconus adaptor.

  • Place nut then ring over pipe
  • Push insert into pipe
  • Push made up pipe end tightly into return (top) manifold fitting
  • Slip ring up pipe until it touches the fitting
  • Tighten nut
  • Lay pipe onto floor as shown in pipe lay out
  • Connect into flow (bottom) manifold, repeat for next circuit


Ensure pipe end has been cut square. Once the pipe has been connected to the return manifold and connected back into the corresponding flow manifold connection, it is now a complete circuit. When all circuits are fitted and secured, take time to check over pipe work and ensure the spacings are correct and there are no kinks in the pipe.



Connecting the underfloor heating manifold

Boiler's return connection Connect the boiler's return to the return valve.
Boiler's flow connection Connect the boiler's flow to the thermostatic valve.
Underfloor heating pipe Connect the underfloor heating pipe to the manifold's return.
Tighten the coupling Tighten the coupling with a wrench.
Position the pipe Position the pipe. Avoid using force by connecting the pipe in a straight smooth bend.
Cut the other end Cut the other end of the pipe to the correct length and connect the same way to the manifold's flow.

Repeat step 3 to 6 for all ports on the manifold.



PipeSulation Board (Underfloor heating mat)


The PipeSulation Board (underfloor heating mat) is the key to lay the pipe correctly.

When using the pipesulation boards start laying the first board in the corner of the room with both overlaps touching walls. The board is strong enough to walk on it and fitted with 11mm insulation on the bottom. The "fully filled" option when the dimples are fully filled with insulation providing stronger / heavy duty surface.

Size: 1000mm x 1000mm x 29mm (= 1 square metre)

The minimum pipe distances are 50mm (straight) and 70mm (diagonal).



Floor Layers

How the floor's layers are built up.

  • Concrete floor
  • Pipesulation Board 1m x 1m
  • Screed 50mm – 75mm
  • Floor covers
  • Border Insulation
  • Underfloor Heating Pipe



Underfloor Heating Mat with Insulation

Insulated underfloor heating mat.

You can easily stop wasting energy by using insulated mats (PipeSulation boards) and border insulation. Easy to fit them and enough strong to walk on it.

  • Assembly by 1 person
  • Supplied as single plate or laminated with 11mm PST insulation
  • Warmth and sound insulation
  • Load bearing plate due to the filled up studs
  • Seamless placed
  • Centre to centre distance 50mm or multiple of this at straight assembly
  • Centre to centre distance 70mm or multiple of this at diagonal assembly
  • Easy to be fitted together
  • CFK free, environment friendly
  • Suitable for pipe ø14 x 2.0mm and ø16 x 2.0mm
  • Color: black
  • Complies with DIN 4108-10, DIN 4102 T1, and DIN 18164
  • Vapour proof according to DIN 18560-3 and DIN 1264. It blocks moisture and floor mixing water
  • System plate PS with 11mm EPS200 DEO insulation
  • Net size: 1000 x 1000 x 29mm (lxwxh)
  • Load bearing capacity up to 60 kN/m²
  • R-value 0,314 m²k/W



Thermostatic valve

This piece of equipment is situated at the manifold and its purpose is to blend down the high temperature water from the boiler to a lower temperature suitable for underfloor heating. The maximum temperature setting for the thermostatic valve is 45°C. Once set this thermostat should not be altered any more.



Filling the Underfloor Heating System

Close aqll ports Close all ports. Turn the thermostatic head to 0.
Close return valve Close the return valve with a screwdriver and screw the hose connector on the return valve.
Connect filling hose Connect the filling hose to the fill and drain valve, and the draining hose to the return valve.
Open the valves Open the fill and drain valve.
Open the first port Open the first port. Make sure all air is removed from the circuit.
Close the first port Close the first port.

Repeat step 5 and 6 for all other ports.