Raising the temperature of mash can be a slow, yet necessary process and using a home brew steam generator can cut the time. However, using steam to heat the mash can also be dangerous as steam can cause sever burns, quickly. While water heated to boiling at 212-degrees Fahrenheit is hot, steam heated to the same temperature will do more damage simply because boiling water begins to cool as soon as it touches your skin. Steam, on the other hand, will need to condense to water before beginning to cool off, giving it more time to inflict more damage and pain.
With that in mind, a home brew steam generator can decrease the time it takes to heat the mash by considering the same principal. Essentially, steam can be generated in a pressure cooker and then piped into the container holding the mash. As the steam enters, it maintains its temperature longer than boiling water will and increases the temperature of the mash at a rate of about one degree centigrade, 33.8 degrees Fahrenheit, per minute.
There are some precautions to be used for making your own home brew steam generator and having the right heat source is needed, or else the heat of the steam may lack enough...