Itho Daalderop fault code E21
Fault code E21 on an Itho Daalderop boiler (including Comfort Classic) means: High-limit thermostat switches the appliance off and the temperature of the central heating temperature sensor was higher than 80°C. Reset the appliance once. If the code comes back, a part is usually faulty, often a temperature sensor. You can check the water pressure and settings yourself; leave work on gas-carrying parts to a certified gas engineer.
After a safety alert (gas, flue gas, combustion), reset no more than once and call in a certified gas engineer. If you smell gas, call your national gas emergency number or 112 immediately.
Cause
Fault code E21 on an Itho Daalderop boiler indicates: High-limit thermostat switches the appliance off and the temperature of the central heating temperature sensor was higher than 80°C.
Fixing fault code E21: step by step
- Let the appliance cool down.
- Check that the radiator valves and underfloor heating circuits are open, so the water can circulate.
- Read the water pressure on the display or gauge. With the system cold it should be between 1.5 and 2 bar.
- Reset the appliance once. If the code comes straight back, do not keep resetting it.
- If the code comes back, too little water is flowing (pump, sludge in the system) or the overheat thermostat is faulty.
Applies to
Itho Daalderop Comfort Classic, 24/50+, 24/80+, 30/50+, 32/80+, 38/80+, Base Cube, Duo.
Fault code E21 on other Itho Daalderop series
The same code does not mean the same thing on every series. Check the rating plate to see which series you have:
- E21 on Base Cube, 24/30 (13L) cw 4, 24/35 (16L) cw 5, 30/35 (16L) cw 5, After 2016, Tot 2016: High-limit thermostat switches the appliance off and the temperature of the central heating temperature sensor was higher than 105°C.
Matching parts
Itho Daalderop parts are available from Instalpunt; shipping to EU countries from €12.95 (€16.95 for more distant countries), usually 3–5 working days.
Based on the cause, these original Itho Daalderop parts fit (always check the type number of your appliance):
- Itho Daalderop cylinder temperature sensor € 59.80
- Itho Daalderop CH temperature sensor wet sensor € 61.16
- Itho Daalderop service set pressure sensor € 133.19
Further reading on this cause
Other Itho Daalderop codes with the same cause
- 0 1 — Open circuit flow sensor (S1)
- 0 2 — Open circuit return sensor (S2)
- 0 5 — Open circuit hot water sensor (S5)
- 0 F1 — Short circuit flow sensor (S1)
- 0 F2 — Short circuit return sensor (S2)
- 0 F5 — short circuit hot water sensor (S5)
Fix it yourself or call an engineer?
Always consult the manual for your appliance and work safely. If in doubt or if the fault comes back, call in a qualified professional. A question about a part? Write to us at info@instalpunt.nl.
Frequently asked questions
What does Itho Daalderop boiler fault code E21 mean?
High-limit thermostat switches the appliance off and the temperature of the central heating temperature sensor was higher than 80°C.
How do I fix fault code E21 on an Itho Daalderop boiler?
First check the cause described above. Then restart the appliance using the reset button. If the message comes back, a part usually needs replacing or the fault needs to be repaired by a qualified professional.
Which parts do I need for Itho Daalderop fault code E21?
That depends on the exact cause. In the Itho Daalderop parts overview at Instalpunt you will find the current price and stock for each part.
Can I fix fault code E21 myself?
You can reset the appliance and check things like the water pressure or settings yourself. Work on gas-carrying parts must be left to a certified gas engineer.
All Itho Daalderop boiler faults and codes at a glance →