Complaint

Symptom

Problem

Action

Insufficient heat

(PS)

Collector loop shows loss of pressure

Collector loop airbound

*Check for and repair leaks

*Check Pressure Relief Valve

*Check air vents if present

*Refill and re-purge system

(PS + DS)

Leak in collector

*Repair or replace absorber plate or vacuum tube

(DS)

No fluid flow in solar loop

High-head pump airbound

Pump improperly located - relocate

(DS)

High-head Pump failure

Replace pump

(DS)

High-head Pump undersized

Upgrade pump

(DS)

Collector loop Piping sagging

Check for sagging pipes, repair and add pipe hangers (one every 4' min.)

(DS+PS))

Pump OK but pump does not run

See Systems not running at correct times

(PS)

Collector loop shows no loss of pressure

Collectors not receiving energy or undersized

*Check collectors

• Orientation
• Tilt
• Shading
• Size of load
• Dirt on collectors

(PS)

Collector loop airbound

Repurge system

(PS+DS)

Circulator impeller Jammed

*Strike sharply when power is applied to free rotor

*Replace pump cartridge or pump

(PS + DS)

Valves or pump isolation valves shut off

Open valves

(PS+DS)

Bent or crushed pipes

Repair/replace pipe

(PS+DS)

Individual tubes in evacuated collector failure

Inspect and replace as needed

(PS+DS)

Obstruction on collector loop

*In the collector array, unequal collector outlet temperature will show obstructed collector

*Check heat exchanger

*flush & refill

(PS+DS)

Potable water lines airbound

*Check air vents in potable water lines for proper location and operation

*Check for air in potable water side of heat exchanger

(PS+DS)

Heat exchanger, Pump(s) or piping too small

Check sizing charts and correct

(PS)

Faulty or incorrectly installed check valve

*Confirm flow is in correct direction

*Check for correct valve operation

*Check for blockages

(PS+DS)

Tempering valve set too low or not operating properly

Reset or replace

(PS)

Large pressure fluctuations in collector loop

Air in loop

*Check for leaks and repair

*Check pressure relief valve and replace if necessary

*Check air vents (if any) and replace or isolate if necessary

*Purge air from system

(PS)

Expansion tank

*Check expansion tank for fluid in air chamber and replace if necessary

*Make sure to set expansion tank pressure to 25# before installing

*Expansion tank too small. Calculate proper size and replace if needed

(PS+DS)

Storage tank loosing heat, especially at night

Tank poorly insulated

Insulate tank to R-10 or more if the tank is in a poorly insulated area

(PS)

Reverse thermosiphoning

Inspect check valve and replace if needed

(PS+DS)

Piping loosing heat

Improper or insufficient insulation

Repair or replace

(PS+DS)

Storage tank gets hot quickly but also runs out of hot water quickly

Storage tank too small

Increase storage tank size or add a second tank

(PS+DS)

Solar tank warm but back-up water heater not warm

Faulty back-up water heater

Repair or replace

(PS+DS)

System does not run consistently

Controller, sensor or wiring problems

See Systems not running at correct times

(PS+DS)

Gradual performance decrease

Collector shaded

Clear obstruction

(PS+DS)

Collector glazing dirty

Clean collectors

(PS+DS)

Excess condensation inside collectors

*Check collector vents or weep holes and clean if needed

*Check for a slow leak inside collector and repair/replace as needed

(PS+DS)

Pipe insulation degrading

Replace as needed

(PS+DS)

Heat exchanger clogged

Check for proper fluid flow through heat exchanger (both sides) and clean or replace as needed

Systems not running at correct times (PS+DS)

Pump(s) running all the time

Controller switch in "ON" position

Move switch to "Auto" position

(PS+DS)

Collector sensor or leads shorted or storage leads broken (find with ohmmeter)

Correct malfunction. Replace sensor if needed

(PS+DS)

Pump(s) never running

No power to controller (AC powered)

Restore power

(PS+DS)

Controller switch in "off" position

Move switch to "Auto" position

(PS+DS)

Storage sensor leads shorted or collector sensor leads broken (find with ohmmeter)

Correct situation. Replace sensor if needed

(PS+DS)

Pump(s) running at intermittent times

Corroded or loose sensor wire connections

Clean wire connections of corrosion and re-connect with watertight connectors or solder connections. Never use wire nuts on sensor wiring.

(PS+DS)

Sensor leads run near 110 VAC wiring

Move sensor wire at least 6" away from 110 VAC wiring or use coaxial cable

(PS+DS)

Sensors incorrectly placed, poorly secured or improperly insulated

Move sensors to correct location and properly insulate

(PS+DS)

Sensors improperly wired

Rewire following instructions supplied with the controller

(PS+DS)

Any of the above

Faulty controller

Check controller and replace as needed

(PS)

PV powered systems

Loose wiring connections

Rewire

(PS)

PV panel undersized

*Check wire size chart for proper wire size and replace wire as needed

*Replace PV panel with proper size

There are a host of good reference materials available, some of which are listed here.
 
Solar Domestic Hot Water Systems - Repair & Maintenance Manual, FSEC-GP-34-88
John Harrison, Bruce Holbaugh, & Tim Merrigan
Published by the Florida Solar Energy Center
 
Solar Hot Water Systems - Lessons Learned - 1977 to Today
Tom Lane
 
Solar Water Heating:  A Comprehensive Guide to Solar Water and Space Heating Systems
Bob Ramlow
 
And don't forget the manufacturers specification and installation manuals.