These work like a dream in our large enclosures.
Was worried they might dry things out and mess up humidity, but not at all. The fan output is gentle and not an in-your-face gust of air.
Set to 100w these already heat better than 150w ceramic heat emitters. They heat enclosures up far quicker than heat lamps etc. The fan heaters themselves also don't get hot, so you can unscrew them right after switching off the power if needed.
Everyone with large enclosures to heat need some of these.