On-Line Training

Differential Controls for Domestic Hot Water Systems ©

Introduction

Why does a domestic hot water (DHW) system need a controls system? Certainly, the basic thermosiphon system can do without controls, as long as the system doesn't need to be drained for freeze protection, a storage tank can be placed above the collectors, and you are satisfied with whatever hot, warm, cool, or cold water you may receive. If you want to get the most from your DHW system you will need to control the flow rate, direction, and temperature of the water.

A controls system consists of three basic elements, all of which must work together properly in order to do an effective job of optimizing your heat collection and delivery system. These elements are (1) the control temperature sensors, (2) the control unit, and (3) the control actuating devices. The first elements, the control temperature sensors, sense the various critical temperature states of the system. The sensed information is then acted upon by the second element, the control unit. Based on this information, the control unit then