Money Saving Option Home > Products > Parenting > Feeding > Bottle Warmer > Money Saving Option Functional Analysis: Instructions for Heating Prepare formula as indicated on packaging. Heat water in microwave/stovetop/kettle. Submerge bottle into heated water until it’s the correct temperature (use thermometer). Instructions found here. More Information Mug picture found here. Worth Noting: Simple way to heat bottle with products you may already have around the home.