Ran out of oil

[username123]

Hi all
We stupidly ran out of oil and have since refilled the tank. We know that it probably needs bled first so have been trying with no success to bleed it and reset. The first problem is we are unsure which is the bleed valve as ours looks different to every other one we've seen (it's a Riello RDB) and is a simple bolt with no bleed nozzle. I've attached photos to show what I mean. We presumed it was the silver one in the photos below and tried unscrewing but it's on so tightly we've been unable to get it to budge at all.
Any help with this at all is much appreciated as we are a bit clueless!

 

[Exedon]

Yes that's correct nut right size spanner would help.
Could try disconnecting flexi into pump and run oil into a container.
Would need to turn of oil first before disconnecting then turn on long enough to clear air.
Do not keep pushing reset button!

 

[username123]

Thanks, yes we thought it was that one. I guess the problem now is getting it to unscrew. We’ve tried spanners, pliers, nothing seems to make it move at all! It seems to be screwed on extremely tight.

 

[muggles]

You either need a decent ring spanner of the correct size, or a socket of the correct size. Something that will grip at 6 faces at once.

 

[robinbanks]

And if it's still tight with a ring spanner on it, stick a length of pipe over the spanner to make for a longer handle. If you're mechanically up to it, and it's a combination spanner, you can also use another combination spanner from the set, hooked into the open end of the first spanner, to increase the handle length. This one is arranged for the "tightening" direction:

The larger spanner would be hooked onto the other finger, or the whole assembly flipped over, to perform a loosening operation. Be careful; the whole lot will slip and fall apart if the larger spanner is allowed to rotate around the finger of the smaller spanner

 

[username123]

Thank you all for the suggestions, very helpful! We managed to bleed it today using a socket set thankfully.
Thanks again!