CH Header Tank Overflow

[andrewt]

I have just had a new larger capacity radiator fitted in my extension as the last one was pathetic. It may be a coincidence but I now have a problem with the header tank overflowing.

I have removed water from the tank and changed the ball valve assembly and re set the float height as low as possible but it still keeps on filling up and overflowing.

I though that the extra fluid and associated expansion of the fluid in the system may be causing the overflow.

Does anyone have any thoughts?

 

[kevplumb]

when is it o/f ing

 

[andrewt]

It drips out more when the heating is on.

I get the occasional drip when the heating. This seems to suggest that the level isn't getting much higher when off.

 

[brumylad]

gas will expand more when heated. Make sure all the radiators are bled. And check that inhibitor is added. Corrosion will produce hygrogen gas.

If you need to bleed the rads frequently air may be gettin sucked in at the vent pipe.

Do you have a hot water cylinder, or is it a combi boiler

 

[andrewt]

I have a hot water cylinder.

 

[brumylad]

its always worth bearing in mind the possibility of a leak in the heating coil inside the hot water cylinder.

This is not uncommon and means the central heating will slowly fill up with water from the hot water cylinder. That is, if the water level in the cold water (tank) storage cystern is higher than that in the central heating expansion cystern.

 

[andrewt]

I was first going to check the system for trapped air i.e. bleed the radiators off as previously suggested and sufficient inhibitor.

Is there a way of checking if it is the a leak in the hot water cylinder to confirm this is the problem?

When you talk about the hot water cylinder is this the tank in the airing cupboard?

 

[brumylad]

yes the HWC is the tank in the airing cupboard.

yes bleed the rads and get any air out first then see how things go.

probably the easiest way to check for a breech in the coil is to get the heating hot, turn it off, tie up the ball in the expansion cistern, drain the central heating so as to just about empty the expansion cistern then watch the level in it to see if it rises. If its a tiny leak you may have to turn on the heating again to see a change, but be careful not to run the central heating pump dry. If the exp. cistern fills the coldwater cistern ball valve should open to top up the lost water from this cistern (as leaks into the exp. cistern)

Maybe someone will have an easier way