Expansion tank level

[nairb999]

14) CHANGING A CISTERN FLOAT VALVE

For the smaller F & E cistern supplying the heating system..........

Adjust float to cut off water when the water level is 100 mm deep to allow for water expansion.

How important is the depth. The level in my expansion tank is 175mm ensuring that the bottom of the overflow pipe is always under water. Could this explain why I continually have to bleed the system ?

 

[Bahco]

The level in my expansion tank is 175mm ensuring that the bottom of the overflow pipe is always under water. Could this explain why I continually have to bleed the system ?

It will explain why your garden is being watered regularly.

Can you check as your overflow pipe should be around 150 mm from the top of the tank.

 

[JohnD]

when you say Overflow pipe, do you mean Vent?

 

[nairb999]

when you say Overflow pipe, do you mean Vent?

It is the overflow pipe. It exits the tank 70 mm from the top but if you can picture an upside down L shape that is 170 mm from the top and hence 25mm or so are submerged in water

ps This is linked to " still getting air in the C/H system after chemical cleaning " - photographs now included in that post as requested by John D