Megaflow Eco Slimline 170i boiler puzzler Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[Psimmo]

Staying in my daughter's flat and she said she had a problem with her boiler- leaking. Looks like it was just a leaky joint in the pipework just above the boiler, tightened it up looks ok at the mo.
In my research (I'm not a plumber) I noticed that this boiler is fitted with an internal expansion tank. However, there is also a large external expansion tank showing only 0.25 bar right next to the boiler and connected by pipework to it. Don't understand. Please advise. And do I need to recharge either or both of these expansion tanks as a result of the leak.
I can see no other discernable need for the external expansion tank as there is no other form of heating on this modern flat.

[stoneyboy]

Hi psimmo,
Yes you must top up the pressure in the system it needs to be 1-2 bar — look at the pressure gauge it should show the maximum.
The problem with expansion vessels inside the boiler casing is that - in theory at least - if it fails a Gassafe plumber is needed. It’s more economic to fit an external pressure vessel which can be bigger than the boiler one.
Regards S