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UFH manifold losing pressure — can't find the leak
Underfloor heating manifold on a new build keeps dropping pressure. System was pressure tested at 6 bar before screed and passed. Now it's been running a few weeks and drops about 0.5 bar a day. I've checked all the manifold connections — all tight. Screed looks fine, no wet patches. Could it be micro-leaks in the pipe joints under the screed? How would you find it?
2 Answers
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0.5 bar a day is significant. If the screed looks dry that rules out a catastrophic leak. Most likely you have a slow weep at one of the compression or push-fit connections on the manifold itself rather than in the floor. Get a pressure test kit on it, isolate each loop one at a time and see if the drop stops — that'll tell you if it's the manifold or the floor pipework.
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Also worth checking the expansion vessel. A waterlogged or failed expansion vessel can cause a pressure drop that looks like a leak. Easy to check — turn off the system, release pressure to zero, and check the vessel pre-charge with a tyre gauge. Should be about 0.5 bar below system fill pressure. If it's zero or water comes out the Schrader valve, you've found your problem.