Alpha CB24/28 Losing Pressure

[meb97me]

Hi

I'm hoping someone might be able to offer some advice.

Our Alpha CB24/28 boiler is losing pressure overnight and needs continual topping up.

In normal operation throughout the evening (going on and off every hour or so) it's fine, but if left for any considerable time ie over night or during the day when were out we're finding the pressure has dropped too low and needs topping up (A&B lights are flashing alternately).

I've been round all the radiators and checked for drips/leaks but cant find any. There's no damp patches on the ceiling so i'm assuming theres no leaking joints etc.

From what i can tell there is no overflow/condensation pipe which i have seen mentioned in any other threads. the system seems completely self contained.

I just wondered if anyone could point me in the direction of a probable cause ie a failed pressure seal somewhere.

or is there some special technique in topping up tht i'm missing apart from topping up the pressure via the little black handled valve on the flexible filling loop pipe

many thanks

 

[BARNY78BG]

have you checked the prv pipe outside is not dripping when boiler is pressurised?

 

[meb97me]

Hi

there appears to be no PRV pipe going outside as i mentioned above.

I can see the PRV valve but it is inline on the heating return pipe so i imagine if it were to blow/leak then it would just leak inside the airing cupboard!

 

[CBF]

pics ?

 

[meb97me]

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• meb97me
• 13 Nov 2012
• 1

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• meb97me
• 13 Nov 2012
• 1

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• meb97me
• 13 Nov 2012
• 1

Whilst I can't feel any wet on any connections it looks as though some of them may have been leaking?

 

[ianmcd]

The PRV pipe is the third from the right it is a 15 mm pipe follow this pipe and see where it goes or diconnect it at the PRV valve and run the boiler and see if it passes

 

[meb97me]

Ah brilliant thanks!!

Doh it even has pressure relief valve written on a sticker underneath the boiler

I think the pipe runs to the guttering outside and looking at it there appears to be a slight weeping coming from it so it looks like its a new valve time!

 

[ianmcd]

Ah brilliant thanks!!

Doh it even has pressure relief valve written on a sticker underneath the boiler

I think the pipe runs to the guttering outside and looking at it there appears to be a slight weeping coming from it so it looks like its a new valve time!

Not necessarily it might just be the Expansion vessel that needs recharging its pretty extensively covered in the FAQs on here, the PRV is spring loaded and sometimes leaks if a bit of dirt has got under the valve seat, turn the power off and turn the valve head a few times , you will feel it clunking and then reset the pressure this is sometimes enough to clear it

 

[meb97me]

Well the gas man came today to do us a landlords gas cert. I'd mentioned about it losing pressure prior to him coming.

He said he couldn't issue one due to a couple of things

1) the boiler losing pressure. He's said the expansion vessel is knackered and will need replacing and the PRV will need replacing as well. The pressure on the gauge when the hot water was running and the heating was on was up to 3.5bar. Does it sound like a reasonable diagnosis? He's quoted £120+vat for parts & fitting does that sound reasonable?

2) There's a flexible metal pipe on the outlet of the gas meter. He's said this isn't allowed according to the regs. Simple and quick to sort by replacing it with some solid copper pipe £40+vat. Does that sound right? Reasonable?

cheers

 

[ianmcd]

yes everything he is saying sounds reasonable and he is certainly not ripping you off with those prices its actually very cheap if you ask me

 

[meb97me]

brilliant thanks

he sounded a decent chap, I was at work when he came and so it was only my missus at home so I didn't actually get to meet him

he seems to come recommended from a local city web forum I use and a lot of people have been happy with his work but I thought it was best to ask for a second opinion

thanks agin

 

[FiremanT]

Well the gas man came today to do us a landlords gas cert. I'd mentioned about it losing pressure prior to him coming.

He said he couldn't issue one due to a couple of things

Same old nonsense. It doen't matter how bad the install is!(to issue a LLGSC) A cert is issued stating the condition of the system at the time of the inspection. The cert will inform the LL of any ttems requiring attention.

 

[twgas]

Did he try recharging the vessel?

 

[meb97me]

So does it sound like he's talking *******s about the flexi gas pipe?

I don't believe he tried recharging it, the missus said he was only there for a couple of mins checking it, i presume that should that have been his first port of call?

Also since he visited i found that black valve thing behind the flexi pipe in the pic above was leaking where as it definitely hadn't been before he visited. It looked like it had been rotated. I nipped up both connections and it stopped leaking.

But the system is now losing pressure all the time inbetween going on and off on the timer rather than just losing pressure over night. I went round and bled all the rads again in case that leak had introduced air into the system.

I'm now having my suspicions about him

He's not done the work yet, he's ordered the parts and was going to give me a call when they arrived.

Is repressurising the expansion vessel something i can test myself?

thanks again

 

[meb97me]

Well it would appear the guy it a bit of a rip off merchant!

I followed the guide in the FAQ's as to repressurising the expansion vessel.

I first checked that when i pressed the middle of the PV valve that water didn't fire out, which it said would indicae that it was knackered. It didn't so i proceeded to respressurise it and open the drain valve. I got about half a bucket of water out of it!!

I then noticed that a couple of the unions on the Heat Exchanger appeared to be weeping and found that the unions needed nipping up a bit. I refilled the system back to 1 bar and bled the radiators and its been fine since! so much for it needing a whole new Expansion Vessel and pressure relief valve!!

Every bloody tradesman with the exception of our chimney sweep has either turned out to be a robbing bastard or have really poor attention to detail and why i generally tend to avoid them like the plague and do stuff myself and this really has just reaffirmed that feeling much to my dissappointment !!