Header tank overflow

[Hopelessplumber]

I have three tanks on the loft: 2 large and one small. The small one occasionally overflows and dribbles down the overflow pipe, and it looks as if the water is coming back out of the outlet at the bottom of the tank.

Can you tell me: -

What is the small tank for? Heating?
What can I do to stop the water backing up?

Hope you can assist.

Hopeless, Hapless and Helpless.

 

[JohnD]

the small tank is likely to be the feed & expansion for your central heating and boiler.

I expect it has a ball valve in it, like you find in a toilet cistern.

First, check the depth of water when the system is cold. It only needs to be a couple of inches above the outlet at the bottom (to allow for expansion). You can adjust the ball valve; if a plastic one, with an adjusting screw near the pivot; if a brass one, by repositioning the ball on the bend at the end, or by bending the brass arm.

Second, look in this small tank and see if it has a layer of fine rust sludge at the bottom and bleed your radiators to see if they contain gas and black water or sediment If so, the overflow may be caused by corrosion of the radiators which generates gas, which displaces a volume of water, that can only escape into the F&E.

Also, look at the water level in the large tank that supplies your bath taps via the hot water cylinder. Compare the height of the water level in this tank with the height of the water level in the small F&E. I don't mean the depth of water, I mean the height of the top of the water relative to the loft floor (or, height above the ground).

Please come back and report what you find.

Has the central heating system ever been flushed or cleaned or filled with inhibitor? How old is it?

 

[bobthebender]

new cylinder
The coil has gone

 

[JohnD]

could be

 

[Hopelessplumber]

JohnD,

Thanks for the prompt response.

Checked the depth when heating is cold; it seems to be constantly up close to the overflow. I've bent the arm of the ball valve so it's now perhaps half full.

Yes - fine layer of rust sludge. House is about 12 years old. Far as I know, the radiators have never been touched. Height of water in large tank is about 8-12 inches higher than in the E & P.

So do you recommend I: -

A) keep an eye on level of the water to see if adjusting the arm has resolved the problem

B) if not, then bleed the radiators ???

Thanks again,

HH&H

 

[JohnD]

bale it out so the depth is a couple of inches. Check that the ball valve is adjusted to maintain that. I recommend tying up the ball valve so you can sponge out the sediment. you don't want it going down into the system and causing a blockage.

Check that the ball valve is not dripping.

Bleed the radiators anyway (the sooner you know the better).

I recommend that you clean and inhibit, especially if the radiators are gassy. This is easy.

If the F&E fills up, maybe you have a leaking coil in the cylinder which is more trouble and expense.