ollski said:
Just re-read the posts here!
Could a flat expansion vessel be the cause of my problem? If so, would I be able to re-pressurise it myself?
Could someone give me a few tips on this?
Many thanks in advance,
Mark.
ELM LeBlanc GVM boiler not retaining water pressure
- Thread starter Mark_C
- Start date
Just re-read the posts here!
Could a flat expansion vessel be the cause of my problem? If so, would I be able to re-pressurise it myself?
Could someone give me a few tips on this?
Many thanks in advance,
Mark.
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It could be except that you say no water has escaped from the pressure relief valve although it has been changed anyway...if its losing over a bar a day there is going to be a noticable leak somewhere unless you have had some plumbing work done recently.
Thanks for the reply.
I'll explain more clearly what happened when the engineer visited on Monday.
At first there was no water escaping from the PRV. There was water escaping from a vent/valve thing at the top right of the boiler which was then dripping out of the case. The part was about 3cm round and had what looked like a car tyre valve cover screwed on to it (so perhaps expansion vessel?). The engineer replaced this first of all.
Now, after that had been replaced and the system re-pressurised the PRV opened. So, engineer replaces the PRV and fills the system up again. Job done he reckons. A few hours later, back to 0 bar, but not via PRV!
No water is escaping from the PRV just now. However, if the expansion vessel is flat, perhaps the water I've put in has just been filling that space? After all, the pressure reading has to be the pressure potential at the air/water barrier. Water is pretty hard to compress, so it's the air compression that drives the overall system pressure.
The entire heating system is 14 years old, and logically it would be a boiler failure, the copper piping is probably the strongest link in the system.
Any comments?
Thanks in advance,
Mark.
I'll explain more clearly what happened when the engineer visited on Monday.
At first there was no water escaping from the PRV. There was water escaping from a vent/valve thing at the top right of the boiler which was then dripping out of the case. The part was about 3cm round and had what looked like a car tyre valve cover screwed on to it (so perhaps expansion vessel?). The engineer replaced this first of all.
Now, after that had been replaced and the system re-pressurised the PRV opened. So, engineer replaces the PRV and fills the system up again. Job done he reckons. A few hours later, back to 0 bar, but not via PRV!
No water is escaping from the PRV just now. However, if the expansion vessel is flat, perhaps the water I've put in has just been filling that space? After all, the pressure reading has to be the pressure potential at the air/water barrier. Water is pretty hard to compress, so it's the air compression that drives the overall system pressure.
The entire heating system is 14 years old, and logically it would be a boiler failure, the copper piping is probably the strongest link in the system.
Any comments?
Thanks in advance,
Mark.
No that's not the expansion vessel, that's the aito air vent.
The Expansion or Pressure vessel is a big thing at the back (probably) of the boiler. Usually they're red, round, the width of the boiler and 2-4 inches thick.
Yes your diagnosis is likely - see FAQ section. If water comes out it's a gonner. If so get some air in a rad while you decide what to do about it, which will give you expansion space pro tem.
The Expansion or Pressure vessel is a big thing at the back (probably) of the boiler. Usually they're red, round, the width of the boiler and 2-4 inches thick.
Yes your diagnosis is likely - see FAQ section. If water comes out it's a gonner. If so get some air in a rad while you decide what to do about it, which will give you expansion space pro tem.
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That was the auto air vent....always leak on these things.
The expansion vessel is behind the boiler, round flat and red. If it has failed it will read as 0 pressure when you put a guage on the car tyre valve on it when the system water pressure is also 0. It should be about 1 bar air pressure. If it is empty the pressure will rise to 3 bar then be released through the prv and outside. Also if diaphragm in expansion vessel is gone the air will go straight into the water and out of the auto air vent, this will drop the pressure but pretty quickly and then be gone.
You say the diaphragm was perished on the prv, if this was the case it would have been leaking a long while, they are usually fine until they open then they never reseal.
Water's going somewhere though we need to find out where its coming out
The expansion vessel is behind the boiler, round flat and red. If it has failed it will read as 0 pressure when you put a guage on the car tyre valve on it when the system water pressure is also 0. It should be about 1 bar air pressure. If it is empty the pressure will rise to 3 bar then be released through the prv and outside. Also if diaphragm in expansion vessel is gone the air will go straight into the water and out of the auto air vent, this will drop the pressure but pretty quickly and then be gone.
You say the diaphragm was perished on the prv, if this was the case it would have been leaking a long while, they are usually fine until they open then they never reseal.
Water's going somewhere though we need to find out where its coming out
Thanks for the replies guys.
I haven't put that much water into the system since the engineer was here on Monday. If the expansion vessel is flat, could the water I've put in have filled the space normally filled with air?
What I don't understand is why the old PRV opened when the AAV was replaced. Especially since the pressure wasn't particularly high at the time.
I haven't put that much water into the system since the engineer was here on Monday. If the expansion vessel is flat, could the water I've put in have filled the space normally filled with air?
What I don't understand is why the old PRV opened when the AAV was replaced. Especially since the pressure wasn't particularly high at the time.
ollski said:
I haven't used the heating since Monday evening. I can guarantee that after putting the pressure to 1 bar it will be at 0 bar after 12 hours!
OK guys, I've found the leak!
I thought there was a funny smell in the kitchen cupboard directly below the boiler so I emptied it and climbed inside and found this valve. This valve is between two pipes directly underneath the boiler:
There is a fast drip coming from the connector controlled by the red wheel. So, how do I fix this? Is it a water off - new washer - water on job?
Or get a plumber in job?
Just for the record it made this mess and much more...
Hopefully this is the one and only leak...
I thought there was a funny smell in the kitchen cupboard directly below the boiler so I emptied it and climbed inside and found this valve. This valve is between two pipes directly underneath the boiler:
There is a fast drip coming from the connector controlled by the red wheel. So, how do I fix this? Is it a water off - new washer - water on job?
Or get a plumber in job?
Just for the record it made this mess and much more...
Hopefully this is the one and only leak...
That will be the leak then...if it's just from the gland nut directly behind the red wheel take the handle off and undo the nut underneath and remove, get an inch of gas ptfe tape (thick) roll into a sausage and wrap it round the spindle then push it down with the nut and tighten it up....job done.
Nice one mate.
Do I need to turn the water off or suchlike? I'm assuming water's gonna rush out when I undo that nut?
Thanks for your help,
Mark.
Do I need to turn the water off or suchlike? I'm assuming water's gonna rush out when I undo that nut?
Thanks for your help,
Mark.
Because I'd rather do it myself if at all possible.
This is a DIY forum after all...
This is a DIY forum after all...
From what I have read its only the gland nut on that valve leaking.
Have you tightened it?
By the way it seems to be a cheap alternative to a bypass and should be almost closed ( clockwise ).
Has that fixed the leak?
Tony
Have you tightened it?
By the way it seems to be a cheap alternative to a bypass and should be almost closed ( clockwise ).
Has that fixed the leak?
Tony
Nut tightened. Job done!
Thanks for all the advice folks - much appreciated!
Cheers,
Mark.
Thanks for all the advice folks - much appreciated!
Cheers,
Mark.
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