primatic cut off balls up! HELP!

Hi guys,
just had two plumbers in,the idea being they disconnect the two pipes from the cylinder and cap it off thus leaving me with a normal working hot water cylinder for a few weeks while i remove the old rads around the house for them to come back and install a new combi system.
they left while tank was filling,now no water is coming from any taps ( except the cold taps fed from the mains)
AND when i try to turn the heating element on for the tank it blows my rcd!
were the disconnected pipes probably earthed further down the line im thinking and now seperated from the tank,no earth?

so no water any reason why? all stopcocks open etc
and rcd trips when switched on at emersion heater tank,any reason why?

thanks gents

It'll be airlocked. If you have a mixer tap, put your hand hand over the spout, open the hot then the cold, leave for a minute then let go. Don't know why your RCD is tripping but don't think it'll be the earth as it'll be earthed through the cold pipe.

did try it downstairs to no joy earlier but after your post again tried it at the bath this time and lots of glug glug glugging later,hey presto water!!
now the thermostat works also as the tank was probably empty to start with!
Thanks again mate much appreciated!
My worry now is are the guys i had in competent,they rushed off sharpish,couldnt get hold of them,left me to deal with it all on me todd!

will have a can now in your honour mate ,cheers again!!

Just checking guys now that these pipes are disconnected, the boiler and rads are now defunct?
Will remove what I can but won't go near the boiler,gas etc.
so this primatic blanking look ok to you? [/img]

That looks OK. They've capped off the primary flow and return pipes.

Bit naughty of your plumbers to rush off without making sure you had hot water. When you have your new system installed, they wouldn't be top of my list.

Thanks whitespirit,pity too as I chose them after all the positive online feedback they had received too.
definitely given me food for thought but also makus you wonder about the feedback you read in the first place!!
thanks for your input.