Underfloor Heating Manifold – A Glossary

underfloor heating manifoldIntro

The underfloor heating manifold can come in all different shapes and sizes. Some will have two circuits, others may have twelve.

The basic principle remains the same, however, and so does the terminology. The components that make up these units can have some pretty confusing names, but we’re here to spell them out for you.

Be baffled by your plumber no more, here is a list of underfloor heating manifold parts along with a brief description of each.

Glossary of underfloor heating manifold terminology


It’s important that each individual circuit of the system is allowed to operate independently and actuators (the four white caps on the lower level of the underfloor heating manifold in the picture above) allow this to happen.

UFH piping can only work efficiently in certain lengths, which is why each underfloor heating manifold will come with a differing amount of circuits.

Each circuit will heat a particular ‘zone’ of the house. A zone may be a whole room or just a portion of a larger room, such as a through lounge. The actuators allow you to turn on the zones that need heating and turn off the ones that don’t, all from one underfloor heating manifold.

Actuators are electronically controlled and work in conjunction with your rooms thermostat.

Adjustable Balancing Valves

Underfloor heating pretty much looks after itself most of the time. However, there will be odd occasions where you’ll need to rebalance the system. Adjustable balancing valves allow you to control the flow of water that runs through each individual circuit. The majority of adjustable balancing valves have flow meters incorporated into them for easy reading.

Ball Valves

These are simple on/off (or isolation) valves that are found on all manner of plumbing fittings. Although uncomplicated, these little beauties are essential, especially when installing the underfloor heating manifold.

They can be seen in the picture above on the right hand side of each level, red (hot) on the top, blue (cold) at the bottom.

Blanking Plate

The internal blanking plate simply stops the mixed water returning to the boiler once it has exited the blending valve.

Blending Valve

UFH runs at quite low temperatures so the water straight from your boiler would be far too hot. A blending valve cools this water by mixing it with the returning water from the circuit to obtain the required heat level.

The water then enters the loops at the correct temperature and completes the circuit. It can then either be pushed around again by the return bypass if still hot enough, or be passed through the blending valve once more.

Boiler Flow and Return

These are the water inlet and outlet for the underfloor heating manifold.

Drain and Fill Bibcock

The bibcocks are situated underneath the two ball valves and are used to connect hose pipes and pumps to the underfloor heating manifold.

This is necessary when flushing the loops to purge the air from the system, as well as for pressure testing.

Flow Meters

Handy monitoring devices that allow you to check the flow rate of each loop. These are usually incorporated into the adjustable balancing valves mentioned above.

High Temperature Cut-Out (Limit Thermostat)

If for some reason the water entering into underfloor heating manifold was too hot, the high temperature cut-out would engage and shut the pump off. Water above a certain temperature can damage the screed if undetected so this final line of defence is essential.

Pressure Gauge

Another self-explanatory one, this is the gauge that reads the pressure of the UFH system.

Return Bypass

As mentioned in the blending valve description above, the return bypass prevents energy wastage by recirculating water that is still warm enough to be pushed around the circuit.

Thermostatic Sensing Element

This is the sensor that reads the temperature of the water passing through the circuit. If it’s too hot it will trigger the high temperature cut-out mentioned above.

UFH Pump

The UFH pump circulates the water around the circuit once it has been mixed by the blending valve.



  1. Charlie West

    I have UFH Heating but have a problem getting insurance. Can you define where the Central Heating system stops and where the UFH starts? I have been trying to find this answer from a number of companies, I am presuming the UFH starts at the Manifold. All pipework valves etc that feed the UFH are part of the Central heating system, it just happens to be supplying UFH heating rather than Radiators.

    • Underfloor Heating Expert

      Hi Charlie,

      To be honest, I’ve never heard of insurance problems due to underfloor heating. Seems odd to me, but that’s not saying much!

      I would tend to agree with UFH starting at the manifold, but if it’s really proving to be an issue the broker should send someone out to assess the property themselves. The onus shouldn’t really be on you, as they can then call foul should a claim arise. Personally, I would push for them to make the decision, that way you will know exactly what you are covered for. There are too many grey areas for them to wriggle out of otherwise.