Stains On Wooden Floor Caused By Underfloor Heating?

[Stanmoor]

We recently moved into a newly refurbished property that has engineered oak wood flooring throughout the ground floor, along with wet underfloor heating in the kitchen area.

Within the kitchen, the flooring has some discoloration / staining, which, when we first moved in we assumed was from a window being left open when it was raining (as it was mostly directly under a skylight). Over the past week or so though, having been running the UFH, it seems as though the discoloration has gotten worse / spread to some other areas.

Could the staining be due to the UFH or something else? I checked the website from where the flooring was purchased and it says it's safe to be used with underfloor heating systems, so I'm not sure what exactly is causing the problem. No staining in the living room area (radiators are there), which is why I suspect it's an issue with the UFH. We've set the thermostat at 21 degrees over the past week in the evenings, and off otherwise. The room doesn't seem to get colder than 20 degrees or so according to Nest (well insulated, I guess..)

Attached are pictures - I'd be grateful for any advice that you can share on why this might be happening and how we can fix it / stop it getting worse (if that's possible!).

 

[jeff the gasman]

Could be damp permeating from below. Floors take a long time to fully dry. And should be dry before laying flooring.

 

[Stanmoor]

Thanks Jeff. So would you initial suggestion be to just wait and see, keep and eye on it and see if it gets better over time? The flooring would have been laid around 6 months ago, but no heating would have been on at all since we moved in.

 

[jeff the gasman]

You don’t have much choice. Monitor the situation.

 

[jeff the gasman]

Check the heating system pressure and if it’s low, top it up to 1 bar. The pressure should hold steady.
If it doesn’t, you have a leak.

 

[Stanmoor]

It was last refilled a few weeks back (as we had radiators taken off for decorating), and it's still the exact same level as before, so no leak. I've taken pics & videos now and so will monitor the situation. Hoping it's just the area below drying out from the heating..