The manifold is the central part of any underfloor heating (UFH) system, where the pipework from each zone converges, and where the supply of hot water from the heat source is fed and sometimes blended.
UFH manifolds can either be used in conjunction with a local pump/blender unit, or coupled directly to the centrally blended/pumped heat source, especially in the case of an air-source or ground-source heat pump, which will be supplying lower flow temperatures.
Ambiente UFH manifolds are made out of stainless steel and have the following components:
- Flow meters – these are located on the flow bar, controlling the volume of water passing through each UFH loop, measured in litres per minute. They can be adjusted by twisting the meter up or down to increase/decrease the flow rate.
- Actuator valves – these are located on the return bar and are used to open/close the individual heating loop. This can be either controlled manually with the plastic cap supplied or more commonly is controlled by a thermoelectric actuator valve, which responds to the ‘call for heat’ from the corresponding room thermostat.
- Air Vent – with the option for a manual or automatic version, the air vent is used to purge the air out of the system that will build up during normal operation. Air vents can also be used during commissioning and routine maintenance stages, when there can also tend to be a build-up of air in the system.
- Fill/drain points are located on both the flow and return bars and are used to fill the system up initially, and to flush the system through to remove air or debris. Sometimes the system may also have to be drained down for emergency or maintenance works. The thread allows for a standard hose connector to be directly connected.
- Pressure gauge – located on the return bar, this monitors the system pressure – an important component to check initially for any loose connections or abnormal drops in pressure when the system is first filled up, which may have been caused by damage to pipework during installation or screeding. It is normal to get a drop in pressure after the initial set-up, but it should maintain at a steady pressure once up and running for a few days, typically between 1-2 bar.
- Isolating ball valves – these valves are positioned between the pumpset and the manifold and are used to isolate the UFH system from the primary pipework when required.
- Ambiente manifolds have a ¾’’ BSP thread for the connection of the pipework loops – the relevant fitting is then supplied for the chosen pipe size – standard UFH pipe sizes are 12mm, 16mm, 17mm and 20mm.
Manifolds are typically supplied in sizes from one port (loop) for small projects, up to 14 ports to serve large areas of heating. It is always best for manifolds to be located in the most central location possible to the areas they are heating, in order to avoid excessive transit pipework passing through any one area, which can cause uncontrollable heat and result in the feeling of ‘patchy’ heat underfoot.
Manifold Pump/Blender Unit
On many underfloor heating systems, the water is pumped and blended locally at the manifold. This is done via a combined pump/blender unit, which is connected to one end of the manifold.
Water from the boiler is fed into the pump/blender unit at approximately 70-80 degrees, which is then blended with cold water returning from the system, to reach the chosen temperature to circulate around the UFH loops – typically in the range of 40-50 degrees. Any of the cooler return water that is not used in blending with the flow from the boiler, is sent back to the boiler to be re-heated.
On larger projects, it is common for the system to be both blended and pumped centrally in the plant room – which then feeds each of the individual manifolds directly. This is especially common in public or commercial buildings such as schools, hospitals and office blocks.
Whether the system is pumped locally or centrally, it is important that the pumping capacity meets what is stated on the design – or looking at it the other way, if there is a limit in pumping capacity, this is a critical design input parameter for the UFH supplier to be made aware of. If the pumping capacity is less than required by the underfloor heating system, then an additional pump will need to be mounted on the primary pipework to the manifold to boost pressure and maintain strong flow to all of the pipework loops.
Ambiente is a specialist supplier of Underfloor Heating systems and we have been working with plumbers and installers throughout the UK for over ten years. We look forward to your project enquiry! Read more about us – www.ambienteufh.co.uk
(Article written by Robert Tuffin, Business Development Manager, Ambiente UFH)