Hi daz thanks for reply
I left everythin in there as figured radiator will keep it all ice free
Wasnt that bad last night but had frozen hoses , pump , and thick ice in tank
by the time id drove to b&q and bought everything though it had mostly thawed out as the sun was on the van ,
I dont like the idea of it running all night but like you say a few quid once a year wont do any harm
Might get a thermostatic plug like above to just keep the temperature constant and use less leccy