Vaillant EcoMAX boiler - pressure problems

[belp]

I had a new EcoMAX 622/E condensing boiler installed about 3 years ago and it has worked well until now, only needing to be filled up now and then. Hot water storage is in a Santon pressurised cylinder.

At the end of last week I started to have a problem and it's been playing up since then. Now whenever the heating goes on the pressure gauge goes up higher and higher until it reaches the maximum, which is number 3 in the red. (Before the heating starts up the pressure is at about 1.5.) then later the pressure goes right down again and then the system needs refilling and the boiler needs restarting. It carries on like this, round and round in a loop. I've had a heating engineer round to look at it and he thinks it might be a problem with the expansion/pressure unit inside the boiler. But he's surprised that it would be this as it's only 3 years old and it's usually a good system and shouldn't go that quickly. What do people think, have they seen this problem before and what would their solution
be?
Thanks very much.

 

[plumberdan]

hey,
It certainly does sound like the expansion vessel is at fault. Just above the cylinder u should see a red expansion vessel, if u have a tyre pressure gauge there is a valve on the top of the vessel remove the cap and test to see what the gauge reads, it should be round about 25psi.
I suspect it will read more than this and that is why the problem is occuring, u will be toppin up the system, the heating will come on and the vessel will be taking more expansion from the system resulting in the pressure relief valve activating and the pressure dropping.

Hope this helps.

 

[Mike Jackson]

Most likely cause is loss of pressure in the expansion vessel. It either needs re pressurising or it may have failed. The pressure needs checking against atmospheric pressure so the boiler needs to be isolated from the system and the boiler drain off open. It should then be pumped up to around 1 bar. If water comes out when the schraeder valve is depressed the diaphragm has gone and the vessel needs changing.

Mike

 

[belp]

Thanks for both of your posts, they were helpful. Just to let you know the outcome - I got another plumber out and he drained the boiler down, tested the pressure and then charged up the boiler's expansion vessel using a sort of bike pump. Now it works fine now, so that's brilliant. Thanks again.

 

[ronaldhicks]

I have exactly this problem and cannot get an engineer out till Fri morning. (tonight is wednesday)
Is there anything i can do to makew the boiler "safe" during the 48hrs between now and when the engineer gets here?

 

[Dotty]

Yes. Turn it off.

There's nothing else I'm afraid you can do.

 

[ronaldhicks]

Thankyou Croppie.
Do I have to turn the mains water off as well?

 

[Howsie]

No you'll be fine leaving that on.

 

[ronaldhicks]

Many thanks Howsie. If I leave the thermo on low so that it only calls for heat a few times during the night and also turn the boiler temp control down to low so it doesn't fire up very agressively would that keep the pressure from rising too quickly, thereby preventing the water from overflowing (and dropping the pressure again very quickly). The other thing I'd considered was leaving the refill valve "dribbling" so as to try and balance the water loss thro' the overflow pipe. Is this trying to be too clever??

 

[Howsie]

It's not going any harm in the short term but you need to get it sorted ASAP.

It's passing water out of a safety device for a reason...

 

[ronaldhicks]

Many thanks again Howsie....very sensible advice!

 

[mumswork]

I am a newly qualified plumber and has a friend with this problem, would really like to help her but wanted to check on here 1st. why would i need to drain system down? also how would i do this? as don't start work experience for 2 weeks.

 

[chris watkins]

Hi & welcome along.
With all due respect if you do not know these basic things it would be best not to start working on a gas boiler there are just to many thinks that could (will) go wrong & your friend will not thank you if it ends up costing her a lot more money cos you wanted to help & start your training a couple of weeks early. I know you must be keen but you should know your limits, trust me.

 

[Killy Bing]

I am a newly qualified plumber and has a friend with this problem, would really like to help her but wanted to check on here 1st. why would i need to drain system down? also how would i do this? as don't start work experience for 2 weeks.

To avoid causing more problems and to makesure that this is the cause, it could be something else, let them get an engineer in and join them for it. Depending on the boiler you might have to remove the casing which puts you in the realm of needing to be gas safe and you would be effectivly breaking the law.

Looks like you need that work experiance

 

[Dotty]

Very good advice given by Chris and Billy.

Thread closed.