It also depends where in Communidad Valencia you are? Valencia covers a large area, and reception varies greatly over this area.
If you are actually in Valencia (City and north of), where BBC1, Itv1,2,3,4 should be there 24/7.
I'm 70kms south of Valencia city and get no break up or loss on my 1.8m and various boxes......but then even 20kms inland from me reception on 1.8s drop off...
(unless you have a fortecstar panel / petal dish in which case your reception is pretty damn good!!!!!)
I have had BBC2, the weakest BBC channels for our area, on a 1m dish at 4 or 5 pm....in the El Saler area, but go inland a few KMs and 1.8ms only keep them in for about an hour or two longer.
and pipino in Javea (about 20kms further south of me!) almost get BBC1 24/7 on his 1.5 gibdish and Humax box....
so reception will depend EXACTLY where you are in "Valencia", and may mean a bit more alignment.
You may also find by simply upgrading your single LNB to an invacom twin makes a big improvement in reception - twins are standard installs (or should be) as single LNB do not, for whatever reason, perform as well as the twins.
And can also be important to make sure the dish is not bent - either in transport or whilst taking down or putting back up again.