Jon Klima, Owner
360 Trout Lane, PO Box 23, Guffey, CO 80820
Phone: 719 479-2281,  Email:
In business for 39 years



The Solar Controls Book© is divided into three sections:


Section 1 - Basic Electrical Principles for the Solar Installer©

Section 2 - Differential Controls for Domestic Hot Water Systems©

Section 3 - Advanced Solar Control Systems©


Below is the Table of Contents and Introduction of each of these three sections.  Each section is being offered as a PDF file at a cost of $10, or $24 for all three sections. Sales tax will be added to all Colorado sales.  I will accept a personal check, money order, or PayPal (your credit card will be processed through PayPal).  After I've received your payment or notice of payment, I'll send your order as an email attachment.


Section 1 - Basic Electrical Principles for the Solar Installer© (80 pages, 1.2MB PDF file)

Introduction ---------------------------------------------------------------------------------


1.1 Ohm's Law, Current, Voltage, and Resistance ------------------------------------


1.2 Kirchoff's Current and Voltage Laws and Review Questions -------------------


     Review Questions ----------------------------------------------------------------------


1.3 Electrical Circuit Calculations and Review Questions ----------------------------


1.4 Power Dissipation and Review Questions ------------------------------------------


1.5 Voltage Sources ------------------------------------------------------------------------


1.6 Using the Digital Multimeter ---------------------------------------------------------


1.7 Transformers ---------------------------------------------------------------------------


1.8 Relays and Solenoids ------------------------------------------------------------------


     Review Questions ----------------------------------------------------------------------


1.9 Solid State Devices --------------------------------------------------------------------


1.10 Reactance - Capacitive and Inductive ---------------------------------------------


1.11 Power Factor -------------------------------------------------------------------------


     Review Questions ----------------------------------------------------------------------


1.12 DC from AC Power -----------------------------------------------------------------


1.13 Soldering Techniques ----------------------------------------------------------------


1.14 Troubleshooting ----------------------------------------------------------------------


     Review Questions ----------------------------------------------------------------------




This section is designed to introduce the installer of solar controls to the basic electrical principles necessary for an understanding of what is occurring when connecting wires and forcing a control system into various operating modes. The operation of a DIFFERENTIAL TEMPERATURE CONTROLLER (DTC) is not at all hard to understand. However, an improperly wired DTC can be seriously damaged when power is applied to it for the first time.


If the control system is properly wired, but the installer gets called back on a troubleshooting service call, will the installer have the necessary understanding of the controls to pinpoint the trouble? Many of the control systems in operation today are more than a simple DTC. Some systems have been custom designed to the job and consist of a relay logic matrix. If such a situation exists, the troubleshooter will have a real job if a system schematic has not been provided as a road map. Even with a schematic, the troubleshooter will have to know how to read it and from that, determine how the system operates. A thorough understanding of the system operating modes is necessary for a quick and accurate determination of the problem and how best to go about fixing it.


It may not be immediately obvious to the installer, but an understanding of basic electrical principles will be a great benefit when troubleshooting begins. Neither employer nor customer will be willing to pay for a damaged controller because of improper installation.


Section 2 - Differential Controls for Domestic Hot Water Systems© (84 pages, 1.13MB PDF file)

2.0 Introduction -------------------------------------------------------------------------------


2.1 Temperature Sensors --------------------------------------------------------------------


2.2 Temperature Sensor Placement --------------------------------------------------------
      Wiring the Sensor to the DTC
      Review Questions


2.3 Differential Temperature Controllers --------------------------------------------------
      ON-OFF and Proportional Controllers
      Short Cycling and Differential Temperature Set Points
      Multi-panel Mounting of Thermal Switches for Freeze Protection
      Review Questions


2.4 Freeze Protection -------------------------------------------------------------------------
    Antifreeze (Closed Loop)
     Recirculation (Open Loop)
     Drain Down (Open Loop)
     Drain Back (Open Loop)
     Drain Back (Closed Loop )


2.5 Over Temperature Protection ----------------------------------------------------------
     Maintenance or Sensor Wiring Junctions
     Air DHW Systems
     Review Questions


2.6 Controller Checkout ---------------------------------------------------------------------
     Sensor Temperature Versus Resistance Curve
     Simulate the Storage Sensor
     Check Out the ON-OFF Controller
     Check Out the Proportional Controller
     Check Out of the Over Temperature and Freeze Protection Options
     Choose the Right Controller for the Job
     Review Questions


Appendix A, Temperature vs. Resistance Charts ----------------------------------------


Appendix B, Sensors Used With Some of the More Common Solar Controllers in      Colorado -----------------------------------------------------------------------------------


Appendix C, Contact Information for Solar Differential Temperature Controllers      Being Marketed in 2009------------------------------------------------------------------




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 decides what action should be taken to place the system in the appropriate operating mode. The control unit then sends control signals to the third set of elements, the actuating devices. These devices consist of fans, pumps, dampers, and valves that, when correctly phased, cause the various system operating modes to occur. All of these actuating devices are used in DHW systems. The pumps and valves would be used in an all liquid system, while fans and dampers would be additional actuating devices for an air DHW system.


Section 3 - Advanced Solar Control Systems© (38 pages, 1.01MB PDF file)

3.0 Introduction ------------------------------------------------------------------------------------------


3.1 The Truth Table ------------------------------------------------------------------------------------


3.2 Older Forced Air Furnaces -------------------------------------------------------------------------


3.3 Older Forced Air Furnaces Integrated With A Solar Heating System Newer Furnaces ---


3.4 A Boiler and Solar for Radiant Floor Heating ---------------------------------------------------


3.5 A Furnace and Solar Air Heating System --------------------------------------------------------


3.6 Ladder Diagrams ------------------------------------------------------------------------------------


3.7 Some Final Points - Wrapping it up ---------------------------------------------------------------
      Electric Forced Air Furnaces
      Truth Table Summary
      Endless control variations




The material presented in Differential Controls For Domestic Hot Water Systems should allow the reader to confidently install and troubleshoot DHW systems. This section should equip the controls installer ­ designer with the background to understand more complex control systems used in residential space heating systems.


When this course was taught at Red Rocks Community College in the 1980s, the section dealing with Interfaces was covered after the Advanced Controls section. With where we are today with heating system controls contained on a printed circuit board, it seems more logical to simply look at how to interface these controls with solar systems and without the need to examine what is on the PC control board.


This section will first deal with how some of the older furnace control systems looked (some are still in operation and still need servicing) and how they were interfaced with solar space heating systems. Then we will look at how the furnace control systems have changed and how to design a typical control strategy for adding solar space heating system controls. The starting point will be the truth table. A truth table can easily be generated that will define the system control strategies and will show all possible combinations of system operation, given the various combinations of sensor inputs. Once the truth table is established, the relay control logic can be designed.




If you interested in ordering an electronic copy, in PDF format, of the The Solar Controls Book©, the complete book costs $24. The individual sections cost $10 each.


To order and pay by check or money order, send your order to the above address and include the email address to which you would like your The Solar Controls Book© sections sent.


To order and pay with a credit card, I use PayPal to process these payments. Just send me an email telling me which sections you want and I'll send an electronic invoice. It will contain instructions as to how to complete the payment. You do not need a PayPal account to go this route.



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This page was last changed on 12-24-2013