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.  


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!