When it comes to picking the right size heat diffuser for your needs, there are a few things to consider. The first is the size of the area you need to heat. If you have a small space, then a smaller diffuser will be sufficient. However, if you have a larger area that you need to heat, then a bigger diffuser will be necessary.
Another thing to consider is the type of material you need to diffuse. Some materials require more heat than others in order to diffuse properly. For example, if you're trying to diffuse essential oils, then you'll need a diffuser that can generate quite a bit of heat in order to vaporize the oils. On the other hand, if you're just trying to warm up a room, then a lower-heat diffuser will suffice.
Finally, take into account how long you need the diffuser to run for. If you only need it for short periods of time, then a lower-powered diffuser will do just fine. However, if you plan on running the diffuser for extended periods of time (hours at a time), then you'll want something with more power so that it doesn't overheat and shut off prematurely.