Sealed system losing pressure and want to check whether this test is valid?

[flanagaj]

Hi,

Our sealed central heating system keeps losing pressure and we have to top it up very frequently. So in an attempt to work out whether it is the pipework at fault or the boiler I have done the following.

1. I connected a pressure gauge to one of the rads and pressurised the system to 3 bar. The 3 bar pressure did not hold and within the hour it was already down to 2 bar.

2. I then isolated the flow and return of the boiler from the system, released the pressure from the system and performed the test again. I could tell the boiler was isolated as the pressure gauge on the boiler stayed constant at 0 bar whilst the system increased to 3 bar.

Given that the pressure still dropped after isolating the boiler I can conclude (unless my test is not valid) that I have a leak in the system pipework. Now this is really concerning as there is no evidence of a leak and I am scratching my head trying to work out what to do next. I have already added a couple of containers of leak sealer some time ago, but this does not seem to have helped.

I can go around and make sure all of the rad valves are tight, but can anyone comment that my test is valid given I have not fully drained the system. Unless the air I am pumping in is dissolving in the rad water which is causing the air pressure to decrease then I would like to think my test is valid.

Any pointers really appreciated.

Thanks

 

[chris watkins]

Testing sounds find.
What pressure do you normally charge the system up to & how tall is the property ? boiler on the ground floor ?

Can you break the heating system down anymore to test which bit may be leaking (cutting in a pair of valves) ?

 

[flanagaj]

Testing sounds find.
What pressure do you normally charge the system up to & how tall is the property ? boiler on the ground floor ?

Can you break the heating system down anymore to test which bit may be leaking (cutting in a pair of valves) ?

The pressure is usually set to between 1 - 1.5 bar. The boiler is located downstairs and it is a single story property. There is only a single zone in the house so breaking the system down further is going to be difficult.

I think it is possible to manually switch the zone valves so that I can test to make sure the cyclinder coil is not perforated?

Apart from that I might have to take up the floor on the landing and try to test the upper and lower floors separately?

 

[chris watkins]

The pressure is usually set to between 1 - 1.5 bar. The boiler is located downstairs and it is a single story property. There is only a single zone in the house so breaking the system down further is going to be difficult.

I think it is possible to manually switch the zone valves so that I can test to make sure the cyclinder coil is not perforated?

Apart from that I might have to take up the floor on the landing and try to test the upper and lower floors separately?

Keep pressure as low as poss (no more than 1 Bar) on the basis that the higher the pressure the faster the leak rate.
Is heating pipe work run in solid floors ? if copper & un-protected this can cause corrosion problems look for damp patches in the screed.
Un-likly to be cylinder coil unless pressure on the other side (HW) is very low, if open vented then overflow it cistern would be running.