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Installing wet underfloor heating: Domestic Heating How To series Part 4

  • 27 August 2020
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Installing wet underfloor heating: Domestic Heating How To series Part 4
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.Part 4: Wet UFH, Filling and commissioning

 

Before putting any floor on top of newly-laid pipes, a new circuit needs to be filled and tested. You don’t want to find leaks once you’ve covered over the pipework!

 

 

In order to combat the effects of introducing air into the system, I take the opportunity of adding a half-litre of Inhibitor into each new pipe loop immediately before connecting it to the manifold. The 70m pipe I’ve just added has an internal bore of 12mm, so it has a capacity of 0.84 litres - plenty of room!

 

As I have a 280-litre thermal store, there is over 300 litres of water which requires system inhibitor. The minimum recommended dosage is 1%, so the 500ml I’ve added only increases the level by 0.17%. It’s a reasonable amount for a top-up.

 

Once the new pipe is finally connected to the manifold, open fully the manual valve (shown here with a yellow tag) and allow water to circulate through the pipe.

 

 

Air remaining in the new pipe will be flushed through by the flow of water and can be released through the valves provided in the distribution manifold.

 

My UFH installation has a modulating pump feeding the manifolds. This has a pressure sensor which detects the open manifold valve and speeds up automatically. In addition I can press buttons on the pump to adjust the flow-rate.

 

UFH modulating pump

 

I usually increase the pump flow-rate in winter when more UFH zones are likely to have their valves open simultaneously.

 

The modulating pump runs continuously, and so needs to be sourced from a reputable manufacturer. Whether the house gets heated is decided by the thermostats in each separate room/zone. There is no overall central time-clock as is required for a radiator-based heating system.

 

Forward to Part 5; Wet UFH, Connecting Controls

Back to Installing wet underfloor heating Part 3

Return to Domestic Heating Part-1: Strategies


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