Leak on unvented pressurised heating system

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Kevine

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Hello,

I have been losing pressure on my system for some time and have gone through a process of elimination over last few months and completed the following:

  • Boiler Service and health checks
  • Replaced a PRV that was causing a tundish overflow
  • Pressure vessel by water tank replacement as it was filled with water
  • Bleeding rads
  • pressure tests which have proved OK
  • Visible checks for any wet patches (no luck)
I am losing pressure on the system gradually worse, filling to 1 bar, that pressure would now be lost in a day, so definitely there is a leak (somewhere) which will likely cause some considerable damage to find/repair.

Is the next step a professional company to empty system and use gas detection? I don't know exactly what will be done here but believe this is next step. Any idea what is the general cost for this, any other steps that could possibly be taken before getting to this step?

Many thanks!
Kevin
 
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Heat exchanger in the boiler? I think there’s a way to check for this, have a search on this site.
 
Has the boiler been isolated from the system and then watched to see if the pressure dropped whilst isolated or if not does it then drop when the system valves are re-opened?
 
Are you mixing up two systems? The unvented equipment has no effect on your heating system. The vessel near your cylinder may not be linked to your heating, and it is not usual for a tun dish to be used on a heating system. When you mention a PRV, is this a pressure REDUCING valve or a pressure RELIEF valve?
 
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Post pics of your setup and boiler, a pic is worth a thousand words
 
Kevine said:
Hello,

I have been losing pressure on my system for some time and have gone through a process of elimination over last few months and completed the following:

  • Boiler Service and health checks
  • Replaced a PRV that was causing a tundish overflow
  • Pressure vessel by water tank replacement as it was filled with water
  • Bleeding rads
  • pressure tests which have proved OK
  • Visible checks for any wet patches (no luck)
I am losing pressure on the system gradually worse, filling to 1 bar, that pressure would now be lost in a day, so definitely there is a leak (somewhere) which will likely cause some considerable damage to find/repair.

Is the next step a professional company to empty system and use gas detection? I don't know exactly what will be done here but believe this is next step. Any idea what is the general cost for this, any other steps that could possibly be taken before getting to this step?

Many thanks!
Kevin
Click to expand...

When you say boiler serviced, How did you service the boiler
Did you analyse the flue gases and take manifold pressure reading.
A wet patch often drops the water pressure quite quickly
 
Last edited:
Some pictures of the system.

Water tank and it's vessel upstairs which the vessel was replaced. Pressure relief valves next to it which was also replaced.

Worcester boiler
 

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Mottie said:
Heat exchanger in the boiler? I think there’s a way to check for this, have a search on this site.
Click to expand...

Will search but boiler was serviced recently so hope the boiler is all good
 
Madrab said:
Has the boiler been isolated from the system and then watched to see if the pressure dropped whilst isolated or if not does it then drop when the system valves are re-opened?
Click to expand...

This hasn't been done. Guess I would need some professional help if needed to try this option
 
oilhead said:
Are you mixing up two systems? The unvented equipment has no effect on your heating system. The vessel near your cylinder may not be linked to your heating, and it is not usual for a tun dish to be used on a heating system. When you mention a PRV, is this a pressure REDUCING valve or a pressure RELIEF valve?
Click to expand...

The vessel near cylinder is just for the water cylinder/tank. The boiler has its own vessel (appears hidden) at the back. The pressure gauge near cylinder vessel is for the heating system though. Yes, tundish is for cylinder.
It is pressure relief valve.
Hope this helps. Thanks
 
DP said:
When you say boiler serviced, How did you service the boiler
Did you analyse the flue gases and take manifold pressure reading.
A wet patch often drops the water pressure quite quickly
Click to expand...

The boiler service was a standard boiler service, if this is part of standard service then this is done and checked. But i will also try to check if this was done.
Could the issue still be with boiler perhaps? Surely there would be some leaking around the boiler if the case.

I assume by wet patch you mean somewhere in the house, nothing is spotted just yet.

Thanks again
 
Thanks all for the responses, have replied where i can. Appreciate any guidance on next steps.
Thanks
 
you are confusing your systems, the unvenetd cylinder and the , loss of pressure on your primary boiler system, have nothing to do with each other, they are seperate mostly and if a problem you would get over pressurising rather than pressure loss, yor pressure loss on the primary system means either a boiler fault or a leak on the pipewrk somewhere, you boiler has its own expansion vessel and its own pressure relief valve, there will be a 15mm pipe from the boiler usually to outside, you need to check to see if any water is dripping from this, also set your boiler when cold at 1.0 Bar, then run the boiler with HW and CH both on for 30 mins and see what the pressure guage now reads, if above 2.7Bar your boiler expansion vessel needs re-charging
 
ianmcd said:
you are confusing your systems, the unvenetd cylinder and the , loss of pressure on your primary boiler system, have nothing to do with each other, they are seperate mostly and if a problem you would get over pressurising rather than pressure loss, yor pressure loss on the primary system means either a boiler fault or a leak on the pipewrk somewhere, you boiler has its own expansion vessel and its own pressure relief valve, there will be a 15mm pipe from the boiler usually to outside, you need to check to see if any water is dripping from this, also set your boiler when cold at 1.0 Bar, then run the boiler with HW and CH both on for 30 mins and see what the pressure guage now reads, if above 2.7Bar your boiler expansion vessel needs re-charging
Click to expand...

Thanks, having an issue/problem on both systems probably hasn't helped me. Vessel replacement and new PRV on the unvented cylinder and a leak on the main system :(

I just checked and there is a pipe from the boiler to outside of house which isn't leaking so i guess it is as I originally thought with a leak on the pipework somewhere. What is the next step here, professional company to gas it?

Thanks
 
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