Got oil filled rad out from loft. Stuck it in van for 3 hours. Just went in expecting a heat wave. Bloody freezing

I put a blanket over pump and rad is at rear. Should be ok. I have a rear heater, same as whats up front.Still takes hours to get through pipes. You would think, as soon as van is warm, it would melt quickly. Drop an ice cube in the house, its water in no time