Losing Pressure, Sealed System, Check List

There are lots of post on here about losing pressure from sealed systems, what I was wondering is, is there a check list that you plumbers go through to work out the most probably cause right through to the most obscure.

My system losses pressure & I accept that I have to top it up every 2/3 months.

This could be something put on as a ‘sticky’

Check easiest things first:

Boiler auto air vent - often slight leak (if within combustion chamber the water will often evaporate off - Corgi job)

Boiler heat exchanger

Boiler safety release valve

General pipework leaks on boiler - some boilers are very incontinent eg. Ocean FF, Saunier Duvals,

Isolating valves on boiler

Radiator valve spindles - especially all non BS2767 Pt10 valves ie most valves fitted round my patch.

Thermostatic valve spindles (remove heads to check)

Valve connections to radiators/pipework

Zone valve spindles

Any other valves (bypass/lockshield/ballofix especially)

All visible pipework/joints

Expansion vessel gradually losing air pressure (quality vessels will hold their pressure over a few years, some however may require significant inflating every year). Vessel should be re-charged to correct pressure and re-checked at a later date - perhaps 3 months later. You can then get some idea of pressure loss.

All invisible pipework/joints ie rip up floor etc

Pipework may have to be isolated in sections to find leak.
Suspect pipework if joints covered in snot.
If a sealed system wind up pressure to just below 3 bar - may help find the leak quicker (don't run the system at this pressure though)

AND... air sucked in which will vent through AAV resulting in pressure loss.

Install Fernox Internal Leak Sealant which should seal the leak you have.

David

Diyisfun said:

My system losses pressure & I accept that I have to top it up every 2/3 months.

Click to expand...

It will be a very tiny leak if it causes a problem only every 2 to 3 months.

Never the less it will theoretically reduce the life expectancy of your system and should be sorted.