Boiler Header Tank Overflowing

[WSB]

Hi,

I have a Potterton Suprima Condensing Boiler and over the past couple of months have had on occasions water coming out of the expansion pipe and causing the small header tank in the loft to overflow, causing water to come out of the pipe from the side of the house.

Initially, I thought it was the ball valve but I have since changed that and still getting the same problems.

I have taken some of the water out of the header so it's about half an inch below the overflow pipe but after a week or so, the same problem.

As it's summer, I've not had the central heating on for about 5-6 months. I also have the hot water heating setting as continuous.

I did try reducing the boiler temp a bit but that made no difference.

So my questions are:

1: What is causing this expansion?
2: Will my boiler cover, cover this?

Thanks!!!

 

[flameport]

1 - a blockage in one or more pipes
2 - possibly, ask them.

 

[picasso]

Another possibility is coil pinholed in your hot water cylinder.

 

[WSB]

Funny Picasso as that's what the Baxi bloke said, along with the fact the cylinder is not covered by my plan....

Ball valve has been changed and tests done to see if the excess water is coming from the vent pipe but neither were guilty.
I switched off the heating controller to rule out an issue with the pump as well.
Still it overflows....
I've been told that the cause of this can be perferations in the cylinder internal piping causing outer cylinder water to be forced in the pipeline and pushed back to into the header tank.
I guess that's what you mean.
Any idea how likely this is the problem?
Before I call a plumber to come and change my hot water cylinder, I just wanted to check with you all whether there's something else I should be considering or further tests I could do?
Thanks in advance.

 

[Gasguru]

An assessment of the pipework layout needs doing first...post a few pics of the airing cupboard pipework, pump, valves etc.

 

[terryplumb]

In your other thread you said nothing was coming from the expansion pipe ??
Which is it ??

 

[vulcancontinental]

Another possibility is coil pinholed in your hot water cylinder.

Is the water level in the feed and expansion cistern lower than the level in the CWS cistern? If so pinholed cylinder coil would be my guess.

 

[sxturbo]

boiler cover does not cover blockages, however they will charge you £600 ish pounds for a power flush