Water hot in expansion tank

[nestudas]

Hope someone can help or offer some advice.

I have a main water tank and smaller expansion tank for the rads.

I have not noticed this before but the water in the expansion tank is heated when the central heating is on.

Is this normal? If not does anyone know the cause and/or cure?

Many thanks

 

[hi-spec plumbing heating]

no it's not normal.
the system is pumping over
check the speed of the pump
boiler stat not to high
sludge in the bottom of the f/e tank

 

[nestudas]

no it's not normal.
the system is pumping over
check the speed of the pump
boiler stat not to high
sludge in the bottom of the f/e tank

many thanks for such a prompt reply, shall check

 

[Bahco]

The water in the expansion tank is heated when the central heating is on.

It will get hot if the heating is on as it is being pumped around the system.

Are you saying water is coming out of the vent pipe and back into the smaller tank?

 

[gas4you]

Pretty warm is normal, but hot and steaming is not.

 

[JohnD]

go and sit by the F&E while someone turns the boiler on and off. See if water comes out of the large expansion pipe which is curved over the top of the F&E but is cut short of the water level.

If not, see if you can detect water or bubbles coming up from the feed pipe in the bottom of the tank.

Look and see if there is much sludge at the bottom of the tank, it may be brown or black. If there is, tie up the ball valve and bale the sludge out. You will probably need to clean the system afterwards if it is sludgy.

Adjust the ball valve so that the water level is only a couple of inches deep when cold.

Check that you have bled all the radiators and they have no gas or air in them. Tell us what colour the water is that squirts out.

Look at the circulating pump and see what speed it is set to.

If you can, post a pic of the pipes, showing the pump, and the small feed and the larger expansion pipe from the F&E where they join the main circulating pipes.