A:Answer Hello Johnny, this is Kelly with Dyson. We don't measure our machines in terms of BTU's. While our machines do have a heating element, they're measured in watts. While in heat mode, the purpose is to provided heated, purified air in to your room. How well it heats your space would vary, depending on factors such as doors and windows, how warm the room already is, the air temperature outside, etc. Also, the TP04 Pure Cool Tower does not have a heater function, as it's only a purifier and fan.
Best Wishes,
Kelly
Dyson Customer Support