Dark stain on wood floors

[CPMacD]

I spotted this dark stain on my wood floor around 3 weeks ago, last time the underfloor heating was on was in December. Yesterday I switched it on again and it seems to be getting bigger. The stain is dark, no cupping or crowning, no sign of water or moisture. Any ideas whether it's a chemical reaction or an actual leakage please.The flat is 8 years old and the wood plank is in front of the door where the water cylinder and manifold are. Thank you.

 

[cjg]

pictures help so we can see,

 

[Gazza91]

Could be leak, could be steam, generally when wood darkens it's because being heated, if it's expanding there is moisture, if not then should be fine.

 

[DaleBergin]

It would be better if you would have provided the pictures but as per your story. You should contact the underfloor heating expert because they encounter these types of problems on daily basis. I was also facing a similar type of problem but it takes a few moments for the experts to diagnose the problem. For your ease, you can contact Suntask Ireland