I am seriously stuck with an underfloor heating system which isn’t getting warm enough. I have previously had it working perfect in January however is been off a year and now decided no to play ball. I have changed the reliance thurmogaurd mixer which has helped and the manifold is now getting hot but the return isn’t so much. I have flushed all loops out and all seem to flow fine, the upstairs radiators flow fine and get hot, but when it’s just underfloor it just doesn’t get to temperature. I have told the customer to leave underfloor on over night to see how it goes.