Flushing rad- frost?

[Ballibeg]

I've a new rad coming on Thursday but could do with getting the old one off and flushing today. Now I'm guessing that will leave plain old tap water in the block until Thursday. Is that bad corrosion and frost wise? Is it better to do in one go?

Thanks,

Dave

[DaveD]

personally I would do it all in one go.....