Boiler pressure going mental

[ben110]

I have a Worchester (cant remember what make will up date) i have been away for a wile and left it off, at the moment i turn it on and it starts up then pressure starts increasing from 0.5 bar and then starts jumping at 1-1.5 bar making a banging sound at that point i turn it off. I have manage to get it going by bleeding the valve at the top of the boiler load of air comes out plus boiling hot water and it kind of settles down, then the next day (having been off) and it does it again.

any idea's?

 

[diyAlex]

I am very much not an expert at all, but we have had similar symptoms with our Vaillant combi.

For us, it was the pressure vessel. This is a diaphragm arrangement and expands/contracts to cope with volumetric changes in water as the temperature varies. It's the air pressure in this part that is the actual reading on your dial.

Ours was damaged and water was being allowed in to the air side. This resulted in the pressure going all over the place, and also the Pressure Relief Valve dumping a load of water outside. No bangs though.

Ours was diagnosed by the BG bloke (we have homecare on the boiler). He said he pressed the valve and water came out as well as air.

 

[BARNY78BG]

hi, boiler model would help, but could be one of a few possible issues,
if it's only going to 1 - 1.5 bar on gauge then doesn't sound like expansion vessel as also if its making noises like banging its quite possibly the pump is stuck/sticking, normally exp vess probs would let boiler operate but would over pressurize on temperature rise then blow off through prv pipe thus dropping the pressure . but it sounds like your boilers overheating

 

[ben110]

thanks barny

back at my house now

its a worchester 24cdi

just tryed starting it again by same method explained. The bleed valve at the top im getting steam out of it. So would make sense its over heating there is steam building up and the pressure gauge is going up then i turn it off as its a little crazy.

anymore idea's????

 

[buck51]

Check the pump like he said and then let us know.

 

[ben110]

doesn't sound like the pump is coming on havent really been here for a wile so can t really recall what it's supose to sound like. Is there another way to check pump is working??

the pump is a reb boshthermotechnik grundfos ups 15-30
i assume if there was somthing stuck in it the four socket head screw around the pump would release it??

 

[HERTS P&D]

Remove the large centre screw in the pump, have a cloth to catch any water and spin the pump with a large screw driver inserted into the centre of the pump. If it is stuck or sticking then its time for a new pump.

Once the pump is turning refit the centre screw and turn on and come back to us.

This video might help.

http://www.youtube.com/watch?v=ECLQr3Z1pFk


Andy

 

[45yearsagasman]

It's the air pressure in this part that is the actual reading on your dial.

 

[ben110]

that's done it. working again

many thanks that has really saved me some hassle.

did as u said undid the screw turned the screw inside put it back and could hear the pump run up (there was a little air in it) now it going

just one more question as to pressure. my system going form 9 deg back to around 20 ish the pressure on the gauge has gone alread from 0.5 to 1 bar do i need to release some pressure so that its at around 0.5 or is 1 bar+ ok??

 

[Terry7556]

1 bar is ok

 

[diyAlex]

It's the air pressure in this part that is the actual reading on your dial.

Is that not right? Please correct it if it is wrong.

 

[45yearsagasman]

The boiler gauge is an indication of the water pressure within the system and not the air in the expansion vessel.

 

[diyAlex]

The boiler gauge is an indication of the water pressure within the system and not the air in the expansion vessel.

That makes sense. I stand corrected, thanks for the clarification

 

[celinaaniston86]

Well, top up pressure to about 1.5 with grey hook, when the unit is cold convert red hook to 1, then keep grey hook above this mark. Always check out stress when unit is in freezing mode or you will get a wrong reading.