Worcester classic 29cdi

[Eddy123]

Hi,

have a problem with a recently fitted worcester classic combi with new pipework and rads .

thought I might have a leak as the pressure was dropping so I have checked all pipes and found no leaks .

I have bled all rads and set the pressure again which started to fall slightly over two days , when hot water is running it drops then when you stop running hot it goes back up to where I set it to then drops again after a while

My question is why does running hot water affect the pressure in the heating pipework when the heating is off ?

 

[jedi]

Im going to have a stab at this one...... Could it be that your diverter valve is faulty?...stuck half way?...

 

[Eddy123]

Im going to have a stab at this one...... Could it be that your diverter valve is faulty?...stuck half way?...

Thanks for the reply , am not sure what a diverter valve is? but if it is the cold water feed in then that's open , the boiler has an internal filler loop where I just pull down on a lever to fill , should something be closed off maybe ?

 

[jedi]

are you checking the pressure when its cold? ie, not used for say an hr?

 

[Eddy123]

are you checking the pressure when its cold? ie, not used for say an hr?

Yes , shows a drop in the morning before any hot water is used , the heating has not been on , just wondering why the pressure is fluctuating with heating off and only hot water in use , didn't think hot water use effected the pipework pressure in the system ?

 

[jedi]

just tried mine, it dropped very very slightly, when in hot water mode, but hardly noticable? by how much is your dropping?

 

[Eddy123]

just tried mine, it dropped very very slightly, when in hot water mode, but hardly noticable? by how much is your dropping?

Just a little as well but then it rises to above what it was at before running the hot , then it drops again so its hard to judge if its still losing pressure as I don't know which is the correct reading , plus if I tap the glass it rises to where I set it to start with.

Think I will just need to wait to see as it took a week to drop half a bar before !

Thanks

 

[jedi]

Maybe your gauge is faulty? mines a brand new boiler and the gauge seems sticky, ie does not move smoothly, get worcester in and see what they have to say about it?....to me it looks like a cheapo ebay gauge..

can you post a pic of it?

 

[gasmanstu72]

the pressure will fluctuate all the time,
when water gets hot it expands and the pressure will go up, when it's cold it'll go down.

it also depends on how much water you have in the system, a system with only a few small radiators will show more of a fluctuation than a larger one.

also, there's an automatic air vent in the boiler and if it's newly installed there could well be some air still kicking around and that will work its way out over time causing the pressure to drop.

 

[Eddy123]

the pressure will fluctuate all the time,
when water gets hot it expands and the pressure will go up, when it's cold it'll go down.

it also depends on how much water you have in the system, a system with only a few small radiators will show more of a fluctuation than a larger one.

also, there's an automatic air vent in the boiler and if it's newly installed there could well be some air still kicking around and that will work its way out over time causing the pressure to drop.

I am not using the heating at the moment so I thought the pressure should stay the same but it seems using hot water makes the pressure fluctuate which I thought was unconnected to the heating pressure ?

 

[gasmanstu72]

the boiler will heat up the same water that's in the radiators, then the mains cold water passes through that to heat up and comes out of your tap hot.

if its not dropped consistently i doubt you have a problem