Controller displays HIGHP or HIGH PRESS and disables solar heating; filter pressure is significantly above normal.

Safety first: Turn off the pump and relieve pressure at the filter air relief before opening any filter or plumbing components.

• Clean or backwash filter: If using a sand or DE filter, backwash according to the manufacturer’s instructions. For cartridge filters, remove and hose off or replace cartridges.
• Check return valves: Ensure all return-side valves are fully open, including any dedicated solar return valves.
• Inspect solar return line: Look for kinks, crushed sections, or closed valves in the return line from the Heliocol array back to the pool.
• Examine filter internals: If pressure remains high after cleaning, inspect the filter for collapsed cartridges or damaged laterals that may restrict flow.
• Re-test system: Restart the pump and monitor pressure. Confirm the HIGHP indication clears and solar can operate normally.