Pressure in boiler 3bar when heating on

[stacey17]

I have a worcester bosch boiler nearly 4 years old its the 24i junior. The pressure is at 1.5 when hot water used or no heating on but as soon as i turn the heating on it rises to just above 3. Can anyone give me some simple instructions on how to repair this or what it would roughly cost to put right. I have bleed the radiators and pressed the pin under the schrader cap i can hear air coming out and a tiny bit of water but don't know if this is normal.
Thanks

 

[Burnerman]

Ther is a pressure relief valve on your boiler that tends to open at about 3 bar, so check to see if there is any water appearing in the overflow pipe outside.
However in your case I would guess that the expansion vessel (red painted tank inside the boiler) needs repressurising with air.
John

 

[stacey17]

I have checked and water is coming out of the overflow pipe outside

 

[Burnerman]

Aha not what we want to see!
This means that the filling loop (the device that fills the central heating system with fresh cold water) is open slightly so your system is too full, and overflowing accordingly.
The filling loop often is a silver braided flexible pipe, with a tap on one or both ends. They do differ though so I don't particularly know which system your boiler has.
Another possibility - but your boiler is a bit young for this - is that a perforated heat exchanger is allowing water to pass from the domestic side into the heating side.
Another minor issue is that when pressure relief valves have opened, they don't always like closing off again, but lets go for the filling loop first!

Just seen your edit, Stacey....when you press the schrader valve you shouldn't see any water at all. This means that its internal diaphragm has split and the complete expansion vessel needs renewing.
John

 

[jackecole]

better off adding an external expansion vessel sometimes

 

[Bunnyman]

What a load of ****** burner man ffs! Pressures fine except when heating running so it's obvious the expansion vessels flat 3 years about right, water often comes from the schrader valve when they r flat! Just needs draining an repressure of the tank an prob a service

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[Youllneverguess]

If water comes out of the Schrader valve, then the expansion vessel is goosed and needs replacing.

*edited Corrected, have to keep Tony happy.

 

[Agile]

I water comes out of the Schroeder valve, then the expansion vessel is goosed and needs replacing.

Are you sure that you have got the name of that person's valve correct?

Or are you confusing it with Erwin Schrödinger's cat ?

If only the OP bothered to read the forum rules and the FAQ in particular he would know all about it.

Tony

 

[Youllneverguess]

I have been up since 5am. I have had a busy evening annoying electricians... so am very tired. Actually thought I would accept a Spell check suggestion. Perhaps I'll call you instead next time?

But you are getting confused with characters from Peanuts. Try not to over think things.

 

[Youllneverguess]

If only the OP bothered to read the forum rules and the FAQ in particular he would know all about it.

Tony

Didn't know they had a FAQ on Schrödinger here?

 

[Agile]

Having got back from some jobs last night at 2230 I had a text from a tenant suggesting a meeting with her landlord at 745.

I did not even bother to answer her.

But at 7.46 pm the landlord called me from the property. But it was only seven minutes away.

I was faced with one of those ex-BG idiots who had stolen the fuse carrier on the spur switch. All just to make it more difficult for those who wanted to put the boiler back into service.

All that was wrong with the boiler was the gas connection nut had been loosened purposley as the tenant wanted a new boiler. I will be fitting one but the ex-BG idiot wont !

 

[Bunnyman]

it does not mean the vessels shot if there is water in it every time!the vaillant often have some water in them if they bin flat for a while as the diaphram inside shrinks when flat. when u blow em up the often take up no problem

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[mysteryman]

I do not believe a word in that last post. Water on the air side of the diaphragm means a failed diaphragm means a new expansion vessel - and it explains the symptoms exactly.

 

[craig51]

Erm, up to 3 LITRES of water can be evident on the air side of the expansio vessel caused by nothing but condenstation.

To prove it has acutally gone, remove the schreder valve, then, repressurise. If water ****es out and continiues, then its bust. 9/10times itjust needs repressurising.

 

[stacey17]

I have checked for water under the cap again and there no longer is any if i have a go at repressurising it what should i do and what pressure should it be i have the worcester bosch greenstar 24i Junior