American Technical Publishers Solar Water Heating Systems: Fundamentals and Installation

Why I reached for this guide

I put this book to work on a recent solar hot water retrofit for a two-person household in a mild, freeze-prone climate. The project was straightforward—an indirect, closed-loop system with a pair of flat-plate collectors feeding an 80-gallon storage tank—but “straightforward” in solar thermal still hides a lot of ways to get things wrong. I wanted a reference that would keep me honest on fundamentals, walk me through sequencing and safety, and help me commission without guesswork. This guide did that, and it did it with a clear, methodical tone that feels written to be used in the field as much as in a classroom.

Coverage and structure

At its core, the book is organized the way an installer thinks:

• System types and components: collectors (flat-plate and evacuated tube), circulation strategies (direct, indirect, drainback, recirculation), freeze protection schemes, heat exchangers, tanks, pumps, valves, controllers, and sensors.
• Design and sizing: estimating loads, understanding solar resource, choosing collector area and storage volume, and calculating flow and head for pump selection.
• Installation procedures: from roof attachments and penetrations to piping, insulation, controls wiring, and sensor placement.
• Code and safety: potable water safeguards, scald protection, venting, pressure relief, electrical basics, and roof work safety.
• Commissioning, troubleshooting, and maintenance: purging air, verifying flow and temperature differential, tuning controls, diagnosing poor performance, and seasonal upkeep.

It’s a 356-page first edition, and it reads like a technical text that’s been road-tested: diagrams are clean, terminology is consistent, and there are procedural checklists that translate well to a jobsite clipboard.

System selection and component clarity

The book’s discussion of system types was especially useful during the early decision phase. It contrasts direct systems (simple, efficient, but freeze-vulnerable) with indirect glycol loops and drainback designs, spelling out climate suitability, pros/cons, and maintenance implications. The component rundowns are not just naming parts; they cover why each piece exists and what failure modes to watch for.

A few highlights I leaned on:

• Heat exchangers: Clear differentiation between single- and double-wall exchangers, with the potable water code implications laid out plainly. That saved me a plan review back-and-forth with the local AHJ.
• Check valves and mixing valves: Practical notes on preventing thermosiphoning and ensuring scald protection with a thermostatic mixing valve at the tank outlet.
• Sensor placement: Simple rules of thumb and diagrams for collector and tank sensors, and the impact of sensor location on controller behavior.

Sizing and performance calculations that stay grounded

Sizing can quickly become either oversimplified or arcane. This guide threads the needle by offering both quick estimation methods and more rigorous step-by-step calculations. I used its approach to:

• Profile daily hot water loads realistically (with weekday/weekend variation).
• Translate solar resource data into expected collector gain for my tilt and azimuth.
• Select a collector area that targeted a reasonable solar fraction without pushing into stagnation risk during shoulder seasons.
• Pair storage volume with array size to moderate temperatures and minimize short-cycling.

Pump selection guidance was practical. The process of tallying head losses through pipe, fittings, heat exchanger, and collector loop, then cross-referencing with a typical wet-rotor circulator curve, lined up closely with the manufacturer’s design manual I used to finalize the model. It’s not a hydraulics textbook—and that’s a good thing. It gives you enough to size confidently, with reminders to validate against brand-specific curves.

Installation procedures that respect real roofs and real plumbing

Where the book earns its keep is in the sequencing of installation tasks and the attention to little details that keep systems reliable:

• Roof mounting and flashing: Standoff spacing, lag screw embedment, and flashing techniques are explained with step-by-step photos. There’s emphasis on sealing penetrations properly and distributing loads to structure rather than sheathing.
• Piping layout: Sensible routing to maintain slopes for air elimination in closed loops, avoiding traps; where to place isolation valves, unions, and purge/flush ports; and insulation guidance that acknowledges UV exposure on the roof.
• Electrical and control: Basic controller wiring, proper sensor cable management, bonding, and separation from line-voltage conductors. It’s not an in-depth electrical manual, but it kept my layout clean and code-aware.

The procedures for charging a glycol loop are solid: pre-mixing glycol to the target freeze point, flushing to remove air, verifying pressure, and using a fill cart or pump to ensure adequate flow during purge. I appreciated the reminder to record glycols’ pH and refractometer readings at commissioning—those notes paid off later.

Code and safety: practical, not perfunctory

I often judge technical books by whether their safety sections read like legal boilerplate or like field guidance. This one is the latter. It covers:

• Potable water safety: Backflow prevention, double-wall HX requirements where applicable, and the necessity of an ASSE-rated mixing valve to manage scald risk.
• Pressure relief and expansion: Where to place PRVs, how to size expansion tanks for the solar loop, and how to orient and support them.
• Electrical basics: Bonding metallic parts, controller protection, and general separation/strain relief practices.
• Roof and jobsite safety: Ladder setup, fall protection basics, hot work cautions, and handling of propylene glycol.

Code citations are general rather than jurisdiction-specific; that’s appropriate for a national text. I still cross-checked with local amendments, but the book’s guidance steered me away from common compliance pitfalls.

Commissioning and troubleshooting that actually work in practice

The commissioning chapter is pragmatic and easy to follow. I used it as a punch list:

• Pressure and leak checks before charging.
• Purge procedure until air noise stops and flow stabilizes.
• Verification of differential controller operation with measured sensor temperatures.
• Baseline data capture: ambient, inlet/outlet at collector and tank, flow rate, and pump amperage.

Weeks later, when the system underperformed on a cool, sunny morning, I went back to the troubleshooting flowcharts. The book’s diagnostic path led me to an air pocket trapped near the collector outlet (caused by a slight dip in exterior piping). The fix—re-purge and re-route a short section to maintain continuous rise—was exactly what the guide recommends. That mix of symptom-based tests and likely causes is one of the book’s strongest contributions.

Maintenance coverage is similarly actionable: checking glycol concentration and pH annually, inspecting and replacing UV-degraded insulation, ensuring relief valve discharge paths are clear, and cleaning collector glazing as needed. None of this is exotic, but it’s easy for new owners or technicians to overlook without a structured plan.

What feels dated—and what still shines

This is a 2013 first edition, and a few areas show their age:

• Controllers: The control strategies are timeless, but the examples are based on older, non-connected controllers. If you’re integrating modern data logging or smart-home interfaces, you’ll need to supplement.
• Product references: Pump and collector model examples don’t match today’s catalogs. The principles are sound; just crosswalk to current spec sheets.
• Market context: There’s little discussion comparing solar thermal to alternatives like heat pump water heaters or PV-powered resistance. For pure installation training, that’s fine, but designers weighing options will want external context.

That said, the fundamentals—heat transfer, hydraulics, safety, and practical layout—are as relevant as ever. The checklists, diagrams, and sequencing keep projects organized, regardless of the specific gear you pick.

Who will get the most value

• Apprentices and technicians entering solar thermal will find a complete foundation that bridges classroom and roof.
• Plumbers crossing into solar will appreciate the potable side and control integration guidance.
• Educators can build lesson plans around the chapter structure and end-of-section questions.
• Experienced designers will still find the commissioning and troubleshooting sections worth having on hand, but they may want more depth on complex combi systems and climate-optimized strategies.

DIY-minded readers can learn a lot here, but I’d caution that roof work, code compliance, and pressure systems deserve professional oversight. The book teaches the right habits; it doesn’t replace local permits or manufacturer instructions.

The bottom line

I recommend this guide. It gave me a reliable framework to design, install, and commission a small solar hot water system with confidence, and it helped me diagnose a real-world performance hiccup without hunting through forums. Despite its age, the fundamentals are well-explained, the procedures are practical, and the safety guidance is jobsite-ready. Pair it with current product manuals and local code requirements, and you’ll have a solid reference you’ll actually use—on the bench while you size, and again on the roof while you build.