What Is a Manifold for Central Heating?

What Is a Manifold for Central Heating?

Manifolds are essentially the control hubs for central heating systems, specifically underfloor heating (UFH). Their main purpose is the water distribution of hot/cold pipes within radiant heating and cooling systems.

In this article, we will give you more information on UFH manifolds including their components, advice on how they need to be connected, how it works, where they should be placed and their cost.

So, what exactly is an Underfloor Heating Manifold?

An underfloor heating manifold is simply the central hub of the system that distributes hot/cold water to each underfloor heating/cooling zones. The pipe loops are secured to these manifolds by compression adaptors.

It is important to understand that manifolds are always supplied in pairs, i.e., a flow and return manifold, together with fixing brackets.

Uponor’s Vario S and Magna Manifold Composition


Uponor Vario S manifolds are made of a stainless-steel material for use in radiant heating systems.

Vario S manifolds come with:
  • Mounting bracket
  • Isolations valves (Optional)
  • Flow meter
  • Fill/drain points

Uponor Magna manifolds are made of a plastic material (glass fibre reinforced polyamide) for use in radiant heating and cooling systems.

Within Magna manifolds we have:
  • Mounting bracket
  • Isolations (Optional)
  • Flow meter

Both manifolds can have additional features such as temperature gauges, pump sets and actuators.

Uponor will confirm these options in the Uponor design services, and all of our manifolds come with a 25-year warranty.

Connecting to the Manifold


When laying the UFH loops, the first pipe end should be connected to the manifold before the loop is laid. Push the pipe-end on the outer side of the coil through and behind the return manifold and connect depending on which pipe is being installed.

If you’re insulating the feed pipes with Uponor conduit, we advise sliding this over the underfloor heating pipe before connecting onto the manifold.

What Are the Components of a Manifold?


Underfloor heating manifolds are comprised of many different parts. These include:
  • Drain Valves and Air Vents – Air valves are located on the ‘flow’ and ‘return’ arms of the manifold. They remove air from the system. The drain valves do the initial filling and draining.
  • Flow Sight Gauges – Flow sight gauges are mounted to each of the flow arms, one allocated per circuit. The flow sight gauges are there to give a visual indication of the floor circuit flow rate. This output is set by the heat losses and floor build up.
  • Thermometer Gauge – A thermometer gauge is attached directly to the manifold, allowing for accurate temperature measurement of the manifold. (OPTIONAL)
  • UFH Manifold Mixing Unit – The Mixing Unit is used to blend the water pumped from the heating source and the floor circuits, and helps to maintain the correct temperature for the entire system (OPTIONAL)
  • UFH Manifold Isolation Valves – The manifold isolation valves are connected to the mixing unit or manifold (OPTIONAL). They allow for testing of the manifold without affecting any of the primary floor circuits.
  • UFH Actuator – The actuator is attached to the manifold, and help to open and close every circuit, enabling the water to flow effectively through the entire system. (OPTIONAL)
  • UFH Wiring Centre – The wiring centre is responsible for controlling and maintaining all the electrical aspects of your underfloor heating system. It works by making a connection between the manifold, the heat source, and the thermostat. (OPTIONAL)

How Does a Manifold System Work?


The manifold works by controlling the flow of hot water throughout the entire underfloor heating system. This helps to maintain a comfortable and even temperature across your floor, and keeps your home warm. The manifold is the hub of your heating system, and acts as the central ‘HUB’ that connects the supply and return lines.

Every pipe manifold is comprised of a flow manifold, which indicates the flow rate of each loop, and a return manifold. Every loop is fitted with an open/close valve that is controlled by an actuator valve that is controlled by the thermostat.

Manifolds can be coupled directly to the pumped heat source or used in conjunction with a pump or water temperature mixing unit. Manifolds can be tested to 6 bar of pressure (for consideration, the typical operating pressure is lower than 3 bar of pressure).

These are some of the features that you want to look for in a manifold:
  • A versatile water temperature mixing unit that rotates 90 degrees and has a slim profile that fits easily into the manifold cabinet
  • The mixing unit is easily transferable from one side to the other without the need to adjust the unit
  • Can pump longer loops than traditional manifold pump sets
  • A manifold temperature gauge for monitoring
  • A temperature mixing valve with a temperature setting range between 30 to 70 degrees

Where Is Best to Place the Manifold?


The manifold location needs to be positioned strategically and as central as possible. This will allow it to have similar pipe length loops throughout the building’s zones, and for easy commissioning of flow with all zone pipe feeds.

This location will allow for a more energy efficient UFH system. It is important to select the manifold position at the beginning of the design process.

Ensure there is sufficient height available, from the floor level to the lower return manifold, to enable easy connection of the UFH pipework (minimum 300mm). Typical locations include understairs cupboards, utility rooms, airing cupboards and cloak cupboards.

We recommend using a qualified installer to handle the underfloor heating manifold installation to avoid future problems.

How Much Does a UFH Manifold Cost?


At Uponor, our UFH manifold price range starts from £125 pounds (two port option) and rises in cost with additional ports and components.

More information on Uponor’s UFH manifolds can be found here.