Air + steam release from the Vent Pipe

[flood]

So I have an ancient open vented system with a relatively new boiler in place (Potterton - 5 yrs old).

When the thermostat on the boiler is turned up to above half (as it has been for the past 5 yrs), the HW has been heating fine.

However recently, when the HW is turned on, after around 10 minutes there is a ticking noise coming from a pipe (I cannot locate!) and then the rumbling noise starts.
The vent pipe then expels air and steam quite violently for around 10 seconds. After this, it stops and the ticking noise stops too.
Also to note, this is an INTERMITTENT problem only...!
This morning it was fine but last week, I woke to these crazy noises at least 3 times out of 5.

Should I get someone to look at this or are there any checks I can do?

 

[kevplumb]

yes it needs sorting its boiling

 

[flood]

Do you think it is a boiler problem?

 

[bengasman]

Open vent systems often suffer from heavy corrosion and/or limescale build up. This can have symptoms like you describe.
Are you sure the system was properly flushed when the boiler was installed?

 

[flood]

I flushed the system myself only a month ago because of this but it doesn't seem to have helped (the problem has been intermittent for a couple of months now)

Also I live in a soft water area

 

[bengasman]

What exactly did you do to flush it?

 

[doitall]

I doubt it's a circulation problem as it's intermittent.

Maybe the pump is breaking down, but I would have have thought the boiler stat and even the PCB as it's a Potty.

The worry is the OP hasn't suggested the overheat stat cuts off.

 

[kevplumb]

The worry is the OP hasn't suggested the overheat stat cuts off.

tbf doitall the op hasnt told us much at all

 

[doitall]

The worry is the OP hasn't suggested the overheat stat cuts off.

tbf doitall the op hasnt told us much at all

He's probably gone off to work to help pay for your pension

 

[flood]

What more d'ya need to know?

I ask this whilst paying for your pension, kev..

 

[kevplumb]

What more d'ya need to know?

boiler model

system type

any valves etc

I ask this whilst paying for your pension, kev.. icon_smile.gif

15 years to early yer paying for that layabout doitalls

 

[flood]

Boiler Model: (not at home)

System Type: http://www.diydoctor.org.uk/project_images/boilers/Conven_s.gif

Valves: No motorised valve and no thermostat on the Domestic Hot Water Storage Tank

 

[bengasman]

That sounds like a gravity system
Leaving a gravity system as it is, is a really poor job imho. Fully pumped systems became the norm as far back as the sixties. The lack of controls will lead to poor performance and poor economy. As the installer was clearly not interested in delivering quality, the wholes system is suspect.
It could be a boiler problem, blockage, or pump.
Do you have a working roomstat and timer?

 

[flood]

The timer on the boiler works so CH and HW can be set.

The roomstat was installed with the boiler and doesnt really work. It doesnt set the temp but turning it up fires the boiler up. It's more an on off switch in disguise

 

[bengasman]

So the roomstat doesn't really work, the cylinder doesn't have a stat at all and the system is playing up.
I'd say you should find yourself a good RGI, and have him check over the entire system.
It will probably cost a few bop as I expect a number of problems to be found.