Filling & Pressurising the UFH system

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A test is performed at a pressure of 5 bar before flooring, screed or biscuit mix is laid to check for leaks and ensure the pipes are at their most expanded. This pressure is to be maintained until screed application is completed in order to ensure that any leaks are identified immediately and prevent the screed cracking later. 6 bar is a lot higher than a system would normally run.

This action can be pressurised for testing purposes with mains water in most cases.

REMEMBER: You must be extremely careful to avoid frost unless anti freeze has been added to the water.

The flow from the mains tap to the filling point on the flow rail (red) of the manifold and the return/waste hose connected from the drain point of the return manifold (blue) to somewhere the return water can drain to.

Filling & Pressurising procedure

1.    Close the isolating valves on the manifold (red and blue ‘butterflies’)
2.    Connect suitable filling pipes to the fill and drain points on the relevant rail as per Figure 1.
3.    Route the pipe connected to drain point on return rail of the manifold to a suitable discharge spot – secure the open end as it can whip about!
4.    Connect pipe from the fill point on the flow rail of the manifold to a mains cold water supply.
5.    All the white caps on the return rail should be closed. They can be closed by turning them clockwise.
6.    All flow meter valves (flow rail) should be closed. They can be closed by turning them clockwise. If you have an Emetti manifold the valve is in two parts, the plastic tube and a lower part – both must be closed.
7.    Open the first white cap on the return rail (at one end) fully by turning anti-clockwise.
8.    Open the flow meter valve above the white cap opened (i.e. on the same circuit) as per Figure 2 and Figure 3
9.    Open the filling and drain points (either a square key beneath the drain point or a small red/blue lever) fully by turning anti-clockwise or quarter turn if the small red/blue lever.
10.    Turn on the mains cold water supply.
11.    You should see the red indicator marker in the flow meter move to the bottom of the tube. This indicates correct flow of the water in and shows there isn’t a blockage. The return hose will probably spit and will have an intermittent flow until the circuit has been purged of all air correctly.
12.    When circuit is full and correctly purged, the flow from the return hose will be smooth. Open the next white cap and corresponding flow meter and close the circuit you’ve done by turning the white cap clockwise as far as it will go. The flow of water should stop immediately, if not, there is still air left in the pipe.
13.    Repeat for the next circuit on manifold until all circuits are filled and vented.
14.    Once all circuits are filled and vented individually, open all the white caps so that water is flowing through all circuits.
15.    Close the drain valve on the return rail drain point and let pressure build for a minute before closing the valve on flow rail fill point.
16. Using a Rothenberger pump or similar ‘pump’ the system up to 5 bar via the flow rail filling point (with the point open!) and then close the system off. Leave for 10 minutes. After this time pressure should have dropped by no more than 1 or 2 bar. If pressure drops significantly, check system for leaks and make sure all connections are tight but not over tightened.
16.    The next stage is to commission’ the system once the heat source is connected, see our guide for this.

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Filling, Pressurising, System, Ufh, Underfloor Heating, Electric Underfloor Heating, Wet Underfloor Heating
Heatmiser Honeywell Devi Emmeti Danfoss Grundfos Strasshofer Reliance Water Control