
Do you need help with your faulty Worcester boiler?
The boiler manufacturer Worcester became known as ‘Worcester Bosch’ back in 1992, although it was actually closer to 1995 when its boilers became branded as Worcester Bosch.
So, chances are, if you own an older Worcester boiler, it’s probably at least 20 years old by now. Older boilers are more prone to faults, and over the years I’ve received quite a few calls about old, faulty Worcester boilers.
It’s no fun having a faulty boiler, especially if you don’t know how extensive the work is or how much it’ll cost to fix.
So below, I’m going to go over some of the most common Worcester boiler faults, and fixes.
NOTE: This blog does NOT cover newer Worcester Bosch or Greenstar models (introduced in 2004).
Common fault 1: Boiler fails to ignite
The Cause: If your boiler boiler goes through its usual sequence, where you hear the fan start and spin, yet the boiler fails to ignite, it’s usually a sign of a faulty air pressure switch – or the tubes going to the switch have degenerated.
The Fix: The air pressure switch and tubes need to be replaced.
Common fault 2: Boiler lockout
The Cause: If your boiler lockout light is flashing, it can be a bit of a tricky one, especially with some of the old junior boilers which can sometimes be reset over a few days. As they get older, they become partial to PCB (printed circuit board) failure which is a potential cause.
The Fix: The PCB needs to be replaced.
Common fault 3: Boiler lockout after trying to ignite
The Cause: This one’s quite specific. If you experience boiler lockout after trying to ignite the boiler three times, this is usually down to the ignition leads or probes becoming worn or dirty.
The Fix: The leads and probes should be replaced.
Common Fault 4: Boiler unresponsive
The Cause: In this instance, the boiler won’t even attempt to start up, despite there being power to the boiler. This is particularly common with the old Highflows and some RSF models, as they were built with overheat thermostats.
The Fix: Check the manufacturer’s instructions and try resetting the boiler by pushing in the red overheat thermostat.
Common Fault 5: Water isn’t getting hot
The Cause: If your boiler is coming up to temperature, but your water isn’t getting hot, it’s probably down to a faulty heat exchanger.
The Fix: The heat exchanger should be replaced.
Always call a Gas Safe registered engineer
A lot of the older Worcester boiler models were very popular, so most qualified Gas Safe registered engineers will probably be experienced in dealing with some of these faults.
Always ask for a fixed price quote, and NEVER try to fix the problem yourself. Always call in the experts, especially with older boilers as there can be numerous parts failing at the same time.
It may be cheaper to replace
Remember, your old Worcester boiler will be a non-condensing boiler, and is likely to be only around 70% – 75% efficient. Parts may still be available, but may be in short supply. Your guarantee will also have expired and you’ll find it difficult to get a service contract.
In situations like the one above, I usually agree to make some small repairs, but explain to the owner that the boiler is on its last legs and that it may be more economical in the long-run to simply replace the boiler.
I find most customers who have experienced around 18 – 23 years of fantastic service from their old Worcester boiler usually decide to choose a Worcester Bosch Greenstar model as a replacement.
A great bonus is that they come with up to 10 years’ no quibble guarantee when you fit the brand’s controls and central heating filter.
Conclusion
If you’re having difficulties with your old, faulty Worcester boiler, it can be stressful – especially when you don’t know the extent of the repairs. To help you out, I’ve listed five of the most common boiler faults, and their fixes, so hopefully this should help you get a better idea.
Remember to always call a Gas Safe registered engineer and ask for a fixed price quote. NEVER attempt to fix it yourself. By following the guide above, you should be able to inform your chosen engineer what’s wrong before he/she arrives.
Good luck!

My boiler goes up to 60 on the heat that cuts out drops right down to 38 before kicking in again, nothing wrong with the thermostat is there anything else it cud be, when I have it on max it usually hits 88
Hello, I hope you can help, I have a worcester 28i junior boiler and for 3 months now it just keeps cutting off and the red light starts flashing. I have to push it back in for up to 2 mins at a time in the hope it restarts. I called a plumber and he said it’s the pcb board, I paid him £300 to fit a new one and 2 days later the same problem happens again. I call back and now I m told it’s a low pressure switch n wants another £160. I can’t afford it and have a 1 year old baby. Can anyone suggest what it may be and what I could do.
My Worcester HC350 has a blank display.
There is power to the boiler the PCB fuses are intact. There does not appear to be any power going to the transformer and then to the display screen. However not sure that I am testing correctly.
Power comes in on the main board where 2No plugs next to incoming. One of the plugs goes to the transformer but has nothing on it – this is the second board I have tried so think that it must be me.
There is 240 at the bottom of the board which looks like it goes to 2No switched in the boiler presumably an air proofing switch and pressure switch.
I have Worcester Greenstar 24i 4 years old and the boiler shuts off if you increase the thermostat setting on the boiler slightly over 1/4 turn.so the heating is low and so is the hot water.
Engineer changed the PCB , Fan & 3 sensors.
Any suggestions ?
Thanks
Thank I guys y helpfully info
This is probably the most informed and helpful advice I have ever seen on the Internet. Thankyou
Worcester boiler, blinking led
Fan was replaced recently, however fan is not working
Plumber want to replace fan and charge 250£ (??)
Many thanks
I have a worcester 28si II boiler, working fine after having some replacements about 16 months back, I have noticed a small amount of water seeping out on the right hand side, we are talking small amounts when the boilers been running, water heating up fine and rads warming as they should,
I have noticed that the bar pressure indicator will drop from 2 to below 1 quite rapidly once i have topped the water up, is this normal?? I will get a engineer out after the easter break, but it would be good to give them an idea what the fault is.
Renting. Heat off, water set to come on and heat on frmand only. Status 0. When I am NOT using water ANY nevermind hot it starts up, blue light and water running thtough first pipe. Could it be connected to next door?