How to Install Water Underfloor Heating Kit

1. Ensure the sub floor is clean and free from dust and debris. It is not compulsory, but recommended to lay a damp proof membrane on top.

Clean the sub floor of all debris and add a damp proof membrane (DPM) if necessary. Any sharp irregularities should be removed either by filing, grouting or cutting away.

2. Lay your insulation on top of the floor (or damp proof membrane). Tape the joins together to make sure there are no gaps for the screed to slip through.

Lay the floor insulation as neatly as possible taking care not to leave large gaps that could fill up with screed. Tape the joints and lay polythene or DPM to stop the screed going under the insulation.

3. Fit the pipe fixing system to the insulation at 90 degrees to the direction that the pipe is going to lay.

4. Fix the manifold to the wall in a suitable, accessible location. The wall must be strong enough to take the weight of the manifold and pipe work. Install the manifold prior to laying the pipes, so you know exactly where the pipes need to run from and return.

Mount the manifold on a wall in a suitable location. Check that the surface is strong enough to support the manifold weight and any connecting pipe work. Always mount the manifold before laying pipe work, making sure you work from the manifold with each pipe loop and connect each pipe tail when it is laid.

5. Fit the pipe to the 'flow' connection of first port (flow is normally marked red). Ensure it is secure and fully sealed. 

Make sure the underfloor heating pipe is fitted to the flow side of the manifold (this is clearly arrowed) once the end of the pipe has been reamed with the tool provided. This ensures the sealing O-rings are not damaged as the pipe is located onto the joint.

6. Start laying the pipe, preferably from the furthest part of the room. When laying multiple pipes we suggest using a pre-agreed plan and marking out on the floor where you expect the zones to be, as well as any areas you want to avoid, such as fixed units. As you return the pipe at the end of the room, don’t try and bend the pipe, but make sure spacing is even. Usually between 150mm - 200mm. No loop should be more than 100m in length. Ensure you have enough pipe left to connect to the return port of the manifold. (Usually marked blue). Repeat this for all other ports.

The pipe needs to be laid out from the manifold to the furthest point of the room and returned back to the manifold in a ‘snake-like’ pattern with approximately 200mm spacing between each run of pipe. Larger rooms may have two or three loops of pipe in them and each loop should be laid in approximate equal lengths (not exceeding maximum length of circ. 80m). Fix the pipe down by walking it into the clips. The pipe will not be damaged by walking over it, due to its strength and multilayer construction.

7. Once all pipe has been laid and connected to the manifold, you then need to pressure test with water or air, leave it for 24 hours, this will flag any leaks anywhere in the system. You can then screed the floor. Which must be left to dry naturally.

Once the entire pipe has been installed the system should then be pressure tested with water. This will ensure that there are no leaks in the manifold, joints or pipes. The screed should be laid immediately after and pressure should be left on while this is being laid. A standard sand and cement screed should be laid in accordance with CP8204. It should be well mixed, well compacted, 75mm thick, and cured not dried.

8. The manifold flow and returns must be plumbed in after the boiler pump and before any other radiator or hot water zone valves, allowing the manifold a complete restricted flow and return from the boiler. This must be carried out by a competent plumber.???

9. The Robbens Systems underfloor heating pack comes with a programmable room thermostat so that the area can be controlled independently from any other room or hot water system. Again the wiring for the thermostat and boiler connections should be carried out by a competent electrician.

10. Once screed is completely dry, using the temperature gauge on the manifold, allow water to start flowing through the manifold and pipes at a low temperature. Slowly increase the temperature over a period of time, until you reached the maximum temperature the floor covering can handle, or you are happy with.

The system should not be turned on until the screed has been allowed to cure as turning the heating on too early could damage the screed. The manifolds have an in-built water temperature control and should be run first at a lower setting to allow the screed and floor finishes to warm up slowly before increasing to its final running temperatures. Start up and final temperatures will be specified by the underfloor heating company.

How to Calculate Flow Rate For Underfloor Heating Manifold

The flow metre on each loop of your manifold can be adjusted to calculate the water flow through the pipe. You would do this by taking the pipe length and dividing by 40. Ie, pipe length 100m / 40 = 2.5 L/min