some get through, but they more and more put filter to keep the heat in that also block (some?) of the infrared from getting in. ah, infrared is a huge spectru

some get through, but they more and more put filter to keep the heat in that also block (some?) of the infrared from getting in. ah, infrared is a huge spectrum. They specifically talk about near infrared (as in near visible light) My space heater is not the "recommended" things but it emit the whole spectrum (heating coil) and even a bit of visible red ligth.