Pressure on boiler drop. Worcester junior 24

[John_]

Hi all, wonder someone can help. The pressure bar on my boiler keep dropping. I've managed to check all joints and they are fine, no leak, except for 1 radiator pipework which is underfloor in the lounge which has laminated solid wood floor for which I am very reluctant to remove, if I really have to then be it 🙁 Do I have any other way to check? I will be damn if it is this one and really gutted if I have to remove the laminate. All pipe works under the floor is plastic with push fit connection btw.

 

[diamondgas]

Hi john_

Do you get much pressure rise from cold to hot when your heating is on? The amount of pressure in the expansion vessel chamber can determine pressure loss sensitivity. The lower the charge in the vessel the quicker the boiler will register any loss! have you checked the prv too? Normaly associated with the exp vessel; it can weep if at some time its been compramised 🙂

 

[John_]

Thank you for your prompt reply diamond. Have checked the prv with no water leakage. First thing i did. When the pressure down to zero, I can't get any hot water but when I fill up the system hot water starts running again until the bar say zero. Is there an easy way to know if the expansion vessel not playing up?

 

[diamondgas]

Pressure boiler to 1 bar, heating system cold ... turn your heating on and watch the gauge ... I consider checking the expansion vessel charge if the pressure rises more than 1/2 bar and will definitely check it if I get 1 bar rise! All depending on size of system and length of time it takes for the pressure to drop taken into consideration TBH 🙂

 

[John_]

It's quite a small system, 6 rads. The pressure drop quite rapidly, from 1.5 to 0 in about 30 secs, sometimes slightly longer, around 1 minute. Must have refill the system more than 10 times last night. However this morning bizarrely, I filled the system to 1.5 bar turned the system on full with heating and hot water on constant, the pressure stabilised at the moment. Going to let it run for a bit and have my brother keeping his eyes on the pressure bar for a couple of hours to see any fall. Is this possible?

 

[John_]

Nah, drop to zero again. Prob got no choice but remove the floor. Damn it!!!

 

[diamondgas]

That's a big leak John_ !!! Let us know how you've got on 🙂

 

[John_]

Yep, a leak. Of all the places it had to be the joint under the solid floor. The rest of the house is not laminated! Typical.

 

[snowhead]

Are you getting any noticeable vapour form the flue when the boiler has warmed up?

Do you have any automatic air bleed vents anywhere in the system?

Before you rip the floor up it might be worth pressurising just the pipework and radiators, with the boiler valved off and fit a guage in the fill loop.

 

[GrahamM]

I assume by Johns last post he has already sourced the leak under the floor.