leaking aav

[paul9367]

I haved a ferroli combi boiler which has started losing pressure.

This has only started since we have stopped using the heating in the last few days.

I have looked at the boiler and there is water on top which is coming from the air vent.

What causes this and would this be enough to cause loss of pressure?

thanks

 

[jimstreet]

yes this would lose pressure if that is leaking, and its caused because the air vent is not shutting off correctly, new aav needed

 

[paul9367]

thankyou

 

[bengasman]

But replacing the air vent will not solve the problem for very long.
The fault is caused by dirt in the system and is likely to end up in the new aav before you know it.

 

[jimstreet]

not every leaking aav is caused by dirt, i have had a completly clean system in my own house with a leaking aav, dirt could be the problem, but the engineer who drains the system to change the aav will assess the situation, not everything is down to a dirty system

 

[bengasman]

i have had a completly clean system in my own house with a leaking aav,

Stick a filter on it for a month, I bet you would not like eat what is in there after a month.

You are right of course, not all the aav's give up due to dirt, only the ones I see.

 

[jimstreet]

i totally agree with you about me not eating whats on my magnaclean fitted on my own system, cause i wouldn't, but its a difference of opinion on this subject, i have my views and you have yours, and yes i agree that a dirty system will bugger aav's, but mine and a few others i have changed, where clean as a whistle

 

[bengasman]

I must say magnacleans do work.
Old system: rads taken off and tipped by guy who worked on it before me.
Then I mainsflushed it a la ChrisR. Then powerflushed. then again mainsflushed to get last bits of residue out. Magnaclean installed just in case, and future protection. It caught about 2 soupspoons full in less than a week. If only the twintech was more reliable.

 

[paul9367]

thanks everyone.

I have now had the aav replaced but am still losing pressure.

All heating pipes are concealed under tiled or concrete floors.

Any suggestions as to how I can go about trying to isolate where this could be?

 

[gas_man_gaz]

if i were you id check the ex-vessel and prv 1st..

what pressure are ya filling the sys to?
what does the pressure rise to with the ch on?
is there any water leaking from the pipe outside?

 

[paul9367]

thanks for the suggestions.

I fill it to 2 bar and when on it rises to about 2.4 bar - certainly not near 3 bar.

I did check the prv outlet this morning and it seemed dry

The expansion vessel has previously been suggested when had a problem in the past and another was added to the system outside the boiler

 

[gas_man_gaz]

id only fill to 1.5bar tops, try taping a clear plastic bag to the prv pipe to ensure the prv/expansion is ok.
how often are ya having to top up the pressure?

 

[paul9367]

thanks.

I have had this problem once before and added leak sealer which seemed to sort problem for about a year.

Maybe I should try this again but just trying to rule anything else out first.

It has dropped from 2 bar to about 1.5 in 2 days

 

[bengasman]

I have had this problem once before and added leak sealer which seemed to sort problem for about a year.

You had a leak.
You did not repair it.
It has grown.
You are doomed
You will probably have to call a plumber in.

 

[paul9367]

I have had plumbers in but as I have tiled floors nobody came up with a suggestion of how to find it and their suggested solution was leak sealer!!!