On the topic of heating spaces such as bathrooms, where typically you only want the heat for a short amount of time (after a shower for example):
Look into infrared heaters, they're much better at heating surfaces (your skin) via infrared radiation (which sounds much worse than it is!) compared to trying to heat up an entire room of air. They provide instant heat.
They've been marketed as being the latest and greatest heater tech, mainly for outdoor areas, for a few years now, but they've been around for decades and are nothing new.
Just thought I'd chip in with an alternative that some of you might not have heard about.