Troubleshooting Your Solar Water Heating System - Troubleshooting Heating Systems

Troubleshooting Your Solar Water Heating System
When hot water is used in a home, it is often difficult to know whether it was heated by the sun or by an auxiliary water heater.
Some solar water heating systems may have indicators which show when there is a problem, but many do not. This fact sheet is
designed to help the homeowner determine whether or not their solar water heating system is working properly and, if not, some
possible steps to remedy the problem. For those that are uncomfortable with small repairs, any reference to remedies requiring repair work should be referred to a repair contractor. Lists of repair contractors are available from the North Carolina Solar Center.
The first step in determining if a solar water heating system is operating properly is to turn off the auxiliary water heater. This is accomplished by turning off the circuit breaker to an electric unit or turning a gas unit to pilot or off. This test should not be attempted in winter months since the availability of solar energy is less and may cause a shortage of hot water even when the system is working properly. During periods of sunny weather and moderate hot water usage, most solar domestic water heating systems will be sufficient to handle the water heating needs of a typical home. If the auxiliary unit has been off for more than a day and bright sun is striking the collectors, the piping to and from the storage tank should be warm to the touch (or very hot--BE CAREFUL).
This means that the collectors are supplying heat. If no heat is felt or significant shortages in hot water are experienced, it is likely there is a problem with the system.
The following is a listing of components contained in most solar systems which may be responsible for poor system performance:

Component

Collectors

Possible Cause
1. Partially shaded
2. Improper orientation
3. Improper tilt
4. Insufficient area
5. Improperly plumbed
6. Dirty glazing

Remedy/Check

1. Reduce shading or move collectors.
2. Check direction; face south +/- 45 degrees.
3. Check tilt; set equal to latitude +/- 15 degrees.
4. Install more collectors.
5. Compare with system schematic.
6. Clean--only when cool.

Component

Differential Controller

1. Improper operation (cycling,
late turn-on)
2. Improper wiring or loose connections
3. Faulty sensor wiring

Remedy/Check
1. Check sensor placement. Adjust for good contact with
piping. Insulate from surrounding air.
2. Compare with system schematic. Check for proper
connections. Tighten loose connections.
3. Check wiring for breaks, metal contact, water exposure
and/or corrosion. Seal all splices.

Component

Piping

1. High heat losses
2. Nighttime thermosiphoning
3. Improperly plumbed
4. Isolation valves closed
5. Flow blockage
6. Low system pressure

Remedy/Check
1. Check insulation for splits, deterioration, absence.
2. Check if collector pipes are warm at night. Check for
pump running at night. Contact installer.
3. Compare with system schematic. Check flow direction.
4. Open valves.
5. Flush system. Check effluent for dirt/scale.
6. Check pressure gauge. Refer to ownerÂ’s manual for
correct pressure.

Component

Pump

1. No power
2. Faulty pump
3. Runs continuously
4. Improperly installed

Remedy/Check

1. Check breaker, pump cord, controller fuse--if any.
2. Listen for irregular noises in pump operation. Feel
pipes for temperature difference. Pipe returning from
collectors should be warmer than pipe going to
collectors.
3. Check control system for breaks and shorts.
4. Compare with system schematic.

Component

Tank

1. Insufficient size
2. High storage losses

Remedy/Check

1. Tank should have roughly 1.5 gallons of storage per
square foot of solar collector area
2. Check insulation and location of tank.