iStore fault code E5
Compressor high pressure.
What E5 actually means
Compressor high pressure on an iStore heat pump. On an all-in-one this is usually the evaporator not getting the air it needs rather than anything wrong inside the refrigerant circuit.
What causes it
- Evaporator coil blocked with dust or lint, the most common by far
- The unit installed somewhere with not enough air movement around it
- Fan failing or slowing
- Very high ambient plus a dirty coil together
Most likely first. That order is from what we actually find on site, not from the manual.
Safe to check yourself
No tools, no covers off, nothing to do with gas, refrigerant or wiring.
- Turn it off at the isolator
- Look at the coil, if you can see it, and check whether it is furred up with dust
- Make sure nothing is stacked against the unit
What we check on site
So you know what you’re paying for.
- Coil clean and airflow check
- Refrigerant pressures against spec
- Fan motor test
- Confirm clearances match iStore's install requirements
Can you keep using it?
Turn it off. You will still have whatever hot water is in the tank, and on most iStore units the electric boost will keep you going while you wait, which is worth knowing if you have a house full of people.
What the fix usually involves
Usually a coil clean and better clearance around the unit. iStore carry a 6-year tank and 3-year compressor warranty, so a genuine refrigerant-side fault inside that period is a warranty job.
Is it worth fixing?
That depends almost entirely on how old the unit is. Past about ten years on hot water and gas heating, and twelve on aircon, a significant repair usually costs more per remaining year than a replacement does — and it’s the same point at which the VEU rebate is worth the most, because old inefficient appliances are exactly what the scheme pays to remove. If yours is young and the fault is a component, we’ll fix it and say so.
Repair or replace? The 10-year rule, and what the rebate is worth →