Mystery...! Pressure Problem - Central Heating

[Vandy]

Hi all, we have a worcester boiler central heating ) with immersion tank.... it feeds around 13 radiators in a 4-5 bedroom house.

Over the past few months we have noticed pressure drop on the boiler... it requires re-pressurising daily and particularly worse when the boiler is NOT working all the time. I have noticed if I turn the heating up and the system remains hot (and boiler working etc.) the pressure does NOT drop... even after a few hours... but if I just simply re-pressurise the system and the boiler is on standby the pressure within a few hours is back at zero...

We have had worcester engineers here to check the boiler and each time they check a few things and say try and see... I have noticed everytime they come (even after 1-2 month) they need to re-pressurise the expansion vessel...

can you think of anything wrong with the system? I can not see any sign of leak in the pipes...granted I am not 100% sure about leak in the ground floor but can't smell or see any sign of damp etc. Thank you.

 

[Allgoode]

Your description gives the prob answer to your query & you will need a GSR to rectify problem.

Just a quick point does the pressure showing on the gauge rise much?

Can't say much more than that but as long as when you explain as you have above any GSR worth his salt will know cause & rectification required,

Thanks,

Andy

 

[Vandy]

Your description gives the prob answer to your query & you will need a GSR to rectify problem.

Just a quick point does the pressure showing on the gauge rise much?

Can't say much more than that but as long as when you explain as you have above any GSR worth his salt will know cause & rectification required,

Thanks,

Andy

Hi, the pressure does not rise much - maybe just 0.3bar. and stays there for as long as the heating is ON... but once we turn down the heating and the boiler stops working (i.e. when the system starts to get cold) the pressure drops to zero...and system loses pressure completely so even if we turn the heating up I can hear lots of noises and air been sucked into the system... radiators often need bleeding too...

 

[Riley]

You’ve had the best advice mate you need a gas safe engineer in.

 

[king of pipes]

You need a service call from a GSI to diagnose the problem.
Kop

 

[chris watkins]

What pressure are you topping the system back up to?
Can you see the safety valve discharge pipe outside the house?

If you don't get this fixed very quickly (given than your post suggests it has been going on for months) you will no longer have much of a boiler / system left with all the corrosion caused by the fresh oxygenated water added !!

As others have said, get another Gas Safe engineer to sort it out.

 

[Stu-B]

Sack of WB and get a proper firm in

 

[OffshoreGas]

Do you need to be G3 to fit an expansion vessel?

 

[Stigster]

Do you need to be G3 to fit an expansion vessel?

If you need to take the casing off the boiler to access it then definitely yes. If it's external then I think not. I will be happy to have this clarified by those more knowledgeable than me on the subject though.

 

[OffshoreGas]

If you need to take the casing off the boiler to access it then definitely yes. If it's external then I think not. I will be happy to have this clarified by those more knowledgeable than me on the subject though.

That was my understanding, personally I’d stick an external one on for £40-50. It’s within the capabilities of most competent DIY’er.

 

[Stigster]

The thing is, I would expect the system to hold pressure fine whilst cold and only lose water through the PRV when the boiler heats up and there is inadequate expansion capacity. OP has the opposite going on. Fine whilst hot, loses pressure when not in use which sounds strange to me.

 

[OffshoreGas]

The thing is, I would expect the system to hold pressure fine whilst cold and only lose water through the PRV when the boiler heats up and there is inadequate expansion capacity. OP has the opposite going on. Fine whilst hot, loses pressure when not in use which sounds strange to me.

I’d misread the original post. I’d still suspect the pressure is being lost when hot but only apparent when the system is cool.