Heating expansion tank - manky water

[DIY_Chimp]

Hi. We have two water tanks in the loft, one large cold tank and one much smaller tank by the side. I understand the latter to be the heating expansion tank. The water in this tank is pretty manky so my question is, does this matter and does it mean the heating system needs some kind of flush? It’s currently open so should it have a lid?

cheers,

chris

 

[conny]

If you have a vented C/H system then yes it's probably the expansion tank. Does the system need flushing? Probably if the water in the tank is manky or the system hasn't been flushed for a number of years. Should it have a lid? Yes. It should also have a thermal shield around it and over the top of the lid. The lid prevents debris falling in and the insulation will help stop it freezing during cold spells. In fact both tanks should be lidded and insulated but not underneath as warm air from the house will help to stop freezing as well.

 

[ReganAndCarter]

Wouldn't get too worried about the state of the water in the heating feed and expansion tank. It's luke warm, stagnant water so will naturally have a bit of bacterial growth on the surface. You could scoop it out with a sieve if you want, but it will soon return. A cover will only stop dust and other airborn debris going in, but will help. The water in the tank rises slightly when the heating is on and drops back when heating off so any muck doesn't really leave the tank.

Only time you want to clean out the tank properly is before you drain down the system. Wouldn't want all that crud flowing down from the tank into the heating system as it drains.