Having read Ed Siretts sealed heating system FAQ (cheers Ed), I'm assuming
our Ferroli Optima 901 has a faulty pressure release valve as it needs
topping up everyday.

I topped up to ~2 bar, and noticed the discharge pipe started dripping,
which pretty much confirms a faulty pressure release valve, right??

A possible solution that Ed suggests, short of getting a new valve, is to
"dislodge dirt on the valve by operating the test knob (often red plastic)
very briefly".

However, I can't fing my test knob! Is this inside the boiler, attached to
the valve? I really have no idea about boilers. What would be the procedure
for getting to the test knob?

If the test knob solution didn't work, I notice I can get a new valve from
the web for about £13. Is it a skilled job fitting it, or is it just a
screw-in thingy?

Cheers,

Ted.