This model is designed for multiple temperature and zoning applications. It has the ability to sense water temperature and maintain an accurate boiler temperature output by only energizing the electric elements for needed output (not full capacity). Electro Industries Boiler models eliminates extra costs associated with relays, extra temperature controls, zone boxes, etc. WarmFlo controller is the 21st century device for your Electro Industries EMB-H-9. It applies to any electric or dual heat system.