The contractor who did the leak investigation in my flat advised to replace the boiler due to leak from pressure release valve . He said the boiler is old - 10 years old and sitting on the floor which is difficult for boiler servicing to standards.
My question is if the boiler is only leaking from pressure release valve - is it not a problem with the pressure, and should a re-pressure fix it instead of expensive replacing boiler ?
I am asking is because I am wary of all the expensive I have spent on the boiler repairs over the past year for different leaks and wanted to understand why this time this contractor recommending replacing boiler instead.
He also recommend one option to install the boiler outdoor , does this sound a good option ?
If it keeps losing pressure then PRV is a likely suspect. Pressure release valve regularly fail. Sounds like boiler installed awkward preventing easy access to be able to change the PRV.
Faulty expansion vessel also a common cause of pressure loss, aswell as leaks of course.
The fact itâs a 10 year old boiler heâs probably thinking time to renew. Life span is typically around 10-15 years. Though I have I have a 20 year old boiler, admittedly itâs being swapped this year though.
Pressure relief valves regularly fail the cost of a new one is ÂŁ30 tops + labour. If its not that then it will be the expansion vessel, this work by a rubber diaphragm allows the water to expand as it get hot and then shrink as it cools down. If the diaphragm is ruptured then as the water is heated its only way out is throught the relief valve. Its one or the other. Neither warrants a new boiler, many gas fitters jump on this for a quick payday.
These are checks a competent heating engineer should do when the system is cold:
Fill system to just over 1 bar pressure. Assuming youâve got a slow leak. There should be an air valve on your expansion vessel. Let any remaining air out of it and see if it is followed by water. If no water, then diaphragm likely intact (but could still be perished as canât see inside). Let the pressure out of the system and then repressurise the expansion vessel. Correct static pressure should be written on a label on the vessel. Typical is around 1bar. Now repressurise the system. If PRV leaks, this needs swapping out. You can buy the part in advance by Googling your boiler make, exact model number or GC number and PRV. If unsure, call any of the spare parts suppliers and they should be able to guide you.
Once the PRV is changed and if the system is still losing pressure then likely you either have a leak somewhere in your pipework outside the boiler or inside your boilerâs heat exchanger. Go check all of your pipework to taps, rads etc. Fixing an external leak is usually straightforward once located. Swapping out a heat exchanger is expensive. We had one done last year under warranty. Job would have cost ÂŁ1k otherwise. The part alone costs ÂŁ700 for our Vaillant boiler.
It could also be as simple as not having enough concentration of inhibitor due to constant pressure loss resulting in constant refilling from the mains water supply and constant bleeding.
Without inhibitor or with an insufficient amount of it, radiators will internally corrode (rust) and off-gas hydrogen into the water. Then that hydrogen fills the tops of radiators (requiring manual radiator bleeding) and also escapes from specific valves designed to automatically expel gasses (automatic bleeding at the boiler). If it does this regularly and sufficient inhibitor is not replaced, the inside of the radiator panel corrodes and becomes thinner, more hydrogen is produced, the water in the radiators is then diluted more with pressure top-ups, and eventually youâll have a very expensive to rectify radiator leak due to panel corrosion. This also dirties the water with iron oxide and other iron particles, and this should be mostly combatted by using a magnetic filter at the boiler site.
Catching the problem before it gets bad by replacing sufficient amounts of inhibitor without too much dilution is all thatâs required. If you have the right amount of inhibitor in the radiator system then the hydrogen production problem is solved.
Move on to the next slightly more difficult problem screening like the expansion vessel that may need repressurising with air (by the use of the Schrader valve and a âbycycle pumpâ).
