Troubleshooting and Fixing a E321 Fault " Hot water negative thermistor coefficient (NTC) error"
on Your Main Eco Compact Boiler
What is a Hot water negative thermistor (NTC) and what does it do?
So a hot water thermistor is used in boiler systems to measure the temperature of the hot water running to your taps. It plays the role of providing the boiler with the correct temperature of what the hot water is reading at. The hot water thermistor also contributes to system protection, it helps prevent the boiler from overheating.
E321 Red Flags!
Here are some red flags down below:
- Lukewarm water: If your water is lukewarm and not as hot as it should be, normally it will come up with this error code or it will be the hot water thermistor which is broken.
- Boiler overheating: If your boiler is overheating it could be because of this error code and that the hot water thermistor isn’t doing its job properly.
While the provided information can be attempted by homeowners, fixing the ” Hot water negative thermistor coefficient (NTC) error” error often requires a qualified gas engineer, specialised knowledge, and tools. Gas-related issues can be potentially dangerous, so it is crucial to prioritise safety. If you are QUALIFIED and confident in your skills and have experience working with heating systems, you can try the troubleshooting steps cautiously. However, if you are unsure or uncomfortable with handling gas-related repairs, it is best to leave it to the professionals to ensure a safe and accurate resolution.
Check out what your allowed to do:
Homeowners – What you can do as a homeowner?
Qualified Gas Engineers – Troubleshooting Tips, And What to Do as a Qualified Gas Engineer?
E321 Troubleshooting Tips:
- Try resetting the boiler
- Make sure all the levers underneath the boiler are open
- Make sure your gas is going to the boiler.
- Call an engineer.
- Check all cables on the thermistor.
- Check for damage
- Clean the thermistor
- Replace the thermistor
What can you do as a Homeowner?
So as a homeowner, before you call out an engineer, here are some things you can do:
- Reset the boiler: Sometimes this one can do the trick, give the good old reset button a press for around 1-3 secs and see if the error code disappears. If the error code is still flashing, we will have to look further into this.
- Check the levers: If you look underneath your boiler, you will find some levers, make sure they’re with the pipe and not across the pipe. (Don’t touch the combi-filling loop lever, they are normally blue)
- Check gas supply: As a homeowner we can make sure there is gas going into the property by checking the lever is up at the mains, if this handle is up, go to a gas appliance within your property such as a gas hob and just double check that gas is coming through.
- Call a qualified engineer.
What to do as a Qualified Gas Engineer?
Before taking the casing off the boiler
As an engineer, what we can do before taking the casing off is double-check what the homeowner has checked just to be 100%.
- Reset the boiler
- Check the levers
- Check the gas supply
After taking the casing is off the boiler.
Once you have checked those things, we can dive right into the boiler:
- Check the cables and connections: We will want to make sure that all the wires to and from the thermistor are connected properly and there is no damage to the wire.
- Check for damage: Make sure the actual thermistor sensor isn’t physically damaged. If it is damaged, it will need replacing.
- Clean the thermistor: This is one people don’t do often, make sure we clean the thermistor because overtime it may collect dust. If the thermistor is full with dust, this will prevent it from doing its job properly and won’t read the correct temperature.
- Multimeter test: Once we have done all that we can do a resistance test on the thermistor using a multimeter to see if it is getting the correct resistance it should be getting. All the correct readings will be in the manual
- Replace the thermistor: If you have come to the conclusion that the Hot water thermistor is faulty, then this will need replacing. If you want to know how to replace this then you can check out our video or check the boiler manual.
FAQ's
Unlike some error codes, you will have to get professional help to fix this error code as it requires some knowledge and testing that a gas engineer has.
The hot water thermistors are made to give off pretty accurate readings. The level of accuracy can vary depending on how old the thermistor is and on the quality of it.
The purpose of a hot water thermistor is so that the boiler can give out the temperature of the hot water you want, so then it isn’t giving out water that is too hot or too cool.
Need help finding an engineer?
Book with us today for reliable and efficient service. If you need help getting an engineer for your heating or plumbing needs, Click the link below to schedule an appointment. Our experienced professionals are here to assist you.
Experience exceptional service that exceeds your expectations.
Need a boiler quote
Get a free quote, done today!
If you would like some further help. Please don’t hesitate to contact one of our dedicated staff members, they will give you the best advice they possibly can to help.
