Dirty expansion tank water in loft Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[DIY_Chimp]

The water in Our small expansion tank in the loft is quite dirty. Does it need to be cleaned or is it ok to leave it? Also, does it need to have a lid?

[stoneyboy]

Hi diy_chimp,
Header tanks are generally pretty dirty because of the rusty steel deposits from radiators. If the tank has a thick sediment in the bottom then yes clean it out.
It’s definitely worth having a lid on the tank even if it’s only a sheet of expanded polystyrene with a weight on it.
Regards S