Ratty had a thread a while back about a 300 watt ceramic heater he installed.
Think the one I picked up for £56 is a slightly cheaper make but very similar.
To be honest it doesn't blast hot air out like a domestic heater, but once run for a few minutes certainly makes a difference - it more supplements the existing heater rather than replaces
I mounted mine (90 panel van) onto the roof cross member above the middle seat so it is angled down towards the windscreen. Ran cables behind cab roof lining, down behind passenger door pillar and then under passenger seat to battery
Can post piccy if interested.
Link to seller attached - it came next day
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