Shower Mixer taps

[Wassaman]

I bought thru Srewfix a fantastic quality mixer shower bath taps.
I removed the old taps, no problem and replaced with new set and all seemed well.
Alas when I turned the water back on the cold water pressure is non existent.
The hot is fed from an Immersion tank, and suffered no change in pressure.
The cold is fed from a tank in the loft.
I've scratched my head till it hurts.
Any of you suffered similar probs and how did you overcome?
Wassaman

 

[taydo]

did you drain the tank to do this job, you could have an air lock. Open the cold tap in the basin and blow up the bath tap if you can, Dont Drown Yourself Though.