vaillant - which tap to open?

[poisonrain]

Hi,
I've a vaillant ecotec plus 831 - need to increase pressure in system (had to cut the bottom out of my cupboard to get to the taps). Picture below.

http://img213.imageshack.us/img213/6144/boiler.jpg

Question is which tap(s) to turn on to increase the pressure. Top of picture is front of boiler.

Thanks for any speedy answers.

Cheers,
PR

 

[DavidDaft]

c and should be another to the left of a

 

[kevplumb]

//www.diynot.com/forums/viewtopic.php?t=160255

somebody has left the white handles off

 

[poisonrain]

Magic - thanks so much guys!!!

PR