Leak or not?

[PJAAAAG]

I have a C/H and HW sealed system with a system boiler (i.e. expansion vessel not header tank). Everything, boiler (Glow Worm Ultracom HXi 30kW), expansion vessel, zone valves, water cylinder etc is in the attic. The number and size of rads seem within the range of the boiler output. A diagram is attached.

About every one or two weeks the boiler doesn't fire up and says fault F25 and pressure gauge on end of expansion vessel says zero (possible causes in manual are check thermistors; air in system or system is too restrictive). To fix the problem I fill up via the filling loop on the expansion vessel to 1.5 bar and everything works fine again.

So, is this due to a leak in pipework (no visible signs) or some other problem on the system (air getting in?). Any suggestions on how to find the fault or elimate any of the possible causes.

There seems to be a lot of water coming out of the system via drain pipes although this may just be the condensate from the boiler as it is in a cold roof attic space.

Thanks in advance for your response.

 

[ianmcd]

if you locate the pressure releif valve discharge point, it should be outside the building and should be turned back to the wall but they are not always done properly, once located tie a plastic bag or balloon over the outlet and see if it gets any water in it, another test is set the pressure to 1.5 Bar when cold then put the heating on and check what the water guage is reading after about 20-30 mins, it will go up slightly when the system is hot but if going up near the 3 bar mark you have an expansion problem. if your diagram is correct then the system PRV is connected after your tundish so you should add another tundish as you have to be able to visibly check if the PRV is discharging.

 

[AGAS]

edit

 

[dilalio]

I have a C/H and HW sealed system with a system boiler (i.e. expansion vessel not header tank). Everything, boiler (Glow Worm Ultracom HXi 30kW), expansion vessel, zone valves, water cylinder etc is in the attic. The number and size of rads seem within the range of the boiler output. A diagram is attached.

About every one or two weeks the boiler doesn't fire up and says fault F25 and pressure gauge on end of expansion vessel says zero (possible causes in manual are check thermistors; air in system or system is too restrictive). To fix the problem I fill up via the filling loop on the expansion vessel to 1.5 bar and everything works fine again.

So, is this due to a leak in pipework (no visible signs) or some other problem on the system (air getting in?). Any suggestions on how to find the fault or elimate any of the possible causes.

View attachment 118065 There seems to be a lot of water coming out of the system via drain pipes although this may just be the condensate from the boiler as it is in a cold roof attic space.

Thanks in advance for your response.

Look up expansion vessel faults and repair.

 

[PJAAAAG]

Thank you ianmcd and dilalio for your suggestions.

No PRV discharge apparent and expansion vessel seems sounds so it is still a mystery.

"Progress" of sorts however, I now need to top up/re-pressurise the system every day so it appears that it is definitely a leak in pipework!

Regards

 

[dilalio]

Fill system when cold to 3bar and check for leaks then... all rad valves and lockshields.