It´s great that there are painters who always try new things! We received this photo from a painter who placed a Roll and Go in the heated paint kettle. This gives you a sturdy rolling surface inside the FlowControl.
Please note that you should then add more water to the reservoir, which should preferably already be warm as this increases the battery life.
It´s also a good idea to apply heated paint or varnish with a roller if the paint is thicker (for example due to the cold). Heating means the paint or varnish will flow much better and will be distributed better throughout the roller. Heated paint or varnish is also less likely to take on the orange peel structure of the roller as it flows better. This is ideal if you´re painting a table top, door or kitchen cupboards. Try it for yourself!