What is Insulation, And what Does it Do? People (well, the climate alarmists) don’t seem to understand what “insulation” is. They think that it means that it makes heat “pile up” inside the source of heat, or in the medium between the insulation and source of heat, so that the source of heat and/or the medium will get hotter than the source of heat and power input. 
There is no such thing as “heat pile up”. This is a non-existent concept. You can think of it, like you can think of a unicorn, but it doesn’t exist. Heat does not pile up, it readily and freely flows into whatever is around it.
Insulation is something that only works in a gaseous environment – it is all about a gaseous environment. Insulation, a blanket, a greenhouse, all work the same way, and that way is preventing convective cooling and air circulation. Insulation in the form of a blanket, a sweater, a greenhouse enclosure, home insulation, etc., is about reducing and eliminating convective cooling, i.e. the loss of warm air. A blanket, or insulation, etc., is about doing the opposite of what the atmosphere does!
In your house, insulation helps prevent the furnace-heated air from escaping your house and being replaced with cold air from outside. It doesn’t make the furnace burn hotter. In your water heater, it helps the water retain its temperature after it has been heated. It doesn’t make the water hotter than the heater.
You can wrap a heat source with as much insulation as you want. All that will happen is that the insulation will reach the temperature of the heat source, and the heat source will not rise in temperature. Insulation is just matter, just material like anything else. When exposed to heat, it will warm, and will conduct that heat outward via diffusion.