Worcester Bosch Boiler Problems: Boiler Faults & Troubleshooting

Worcester Bosch Boiler Problems: Boiler Faults & Troubleshooting

Encountering a problem with your Worcester Bosch boiler can be a stressful and worrying experience, that’s why we aim to remove the complexity of 5 of the most common boiler faults.

Encountering a problem with your Worcester Bosch boiler can be a stressful and worrying experience, that’s why we aim to remove the complexity of 5 of the most common Worcester boiler faults and provide you with quick fixes and a troubleshooting guide so that you can rest easy.

What are the most common Worcester boiler problems?
1. Lack of hot water
2. A leaky boiler
3. Boiler losing pressure
4. Banging noises
5. Overheating

What are the common causes?
a. Faulty heating pumps
b. Degraded parts
c. Faulty diverter valves
d. Stuck Y/S-plan valve
e. Faulty PCB unit
f. Lack of power
g. Incorrect installation

1. Worcester Boiler No Hot Water

In order to make a diagnosis please consider which of the following applies to you:

  • No heating + no hot water
  • Heating works + no hot water
  • Cold water works + no hot water
  • No hot water ONLY in the shower

If you have no heating and no hot water there’s a good chance your boiler is suffering from a lack of power. If there are no lights on and the control panel looks blank, you may need to check the fuse for your boiler among other things to get the power back up and running. Once you’ve done this, reset your boiler and you should be back up and running as usual.

Other power fixes: Check the RCD (fuse box) hasn’t tripped, check electric metre (if you’re on one) has enough credit, fused spur may be at fault or PCB (Printed Circuit Board) Failure which will require an engineer’s assistance.

If the power is not the issue but you still have no heating or hot water, it may be a fault with your heating pump. To diagnose this simply check to see if the flow or return pipes are warm. If you can’t feel any heat, the pump may not be working. Alternatively, we recommend you check that the pilot light has not gone out.

If you have no hot water but the heat still works this is most often a sign of a faulty diverter valve. It can be expensive to get a new one fitted, so first of all check that it isn’t faulty S-plan, Y-plan or zone valves.

If you have no hot water only in the shower it could be one of two options: the mixing valve in the shower is broken or stuck or the anti-scalding device is set to the wrong position. It is reasonably cheap to get a mixing valve replaced and the anti-scalding device cannot change itself, so unless you’ve just moved into a new place or you’re staying somewhere new, we recommend it is probably just the mixing valve.
To change the anti-scalding setting you turn it up or down behind the shower’s temperature tap/knob.

2. A Leaky Boiler

Diagnosis: A Worcester boiler with a leak will usually result in a boiler with low pressure and a boiler that is locking out. The fault code is likely to be EA338.

Cause: the common cause for a leaking boiler is blown pump seals which can happen over time to any boiler.

Fix: Leaks can be, but are not always, serious. Check an engineer isn’t needed by asking these following questions:

  • Is the pump insecure? Are the seals degrading? If yes: new pump unit needed.
  • Could the pressure have exceeded 1.2-2.0 bar and blown the pressure relief valve? If yes: new pressure relief valve needed.
  • Is the pipework leaking? If it’s just soldering joints, the job is an easy fix. If the pipework is incorrect get a Gas Safe Engineer on the job.
  • Has it been raining a lot? If rainwater has caused your leak this means the flue has been fitted incorrectly and water is leaking down the flue into the boiler! Get an engineer for this urgently.

Top tip: replacing the entire pump unit is a lot quicker than just replacing seals and you will also find the price difference is not too much. Always remember to reset the pressure to 1.3 bar once you’ve fixed a leak or a pressure related fault.

3. Worcester Boiler Losing Pressure

Cause: If you have a low-pressure issue this will always be down to a leak – somewhere. You will need to check your entire central heating system, from radiators to valves or even joints and pipework.

Fix: Problems arise when a Worcester boiler gets below a certain pressure which causes it to “lockout.” The initial fix is to re-pressurise it using something called the external filling loop but there is only one long-term fix and that is to find the leak and fix it.

4. Banging Noises

Diagnosis: Does your Worcester Boiler fault make reference to loud banging noises?

Cause: Usually, there is either an airlock in the central heating pump or the heat exchanger is kettling. But noises can be caused when limescale or sludge builds up – particles hitting the sides of your boiler or bubbles popping may be the cause.

Fix: If it’s just a build-up, a quick power flush through with an inhibitor and cleaner should help. If you need to remove an airlock in a Worcester boiler pump, this can usually be an easy fix as long as the boiler was fitted with a bleed screw.

However, if your heat exchanger needs replacing this could be quite a costly issue of about £500. The tell-tale sign for a kittling heat exchanger is the noise that sounds like the whistling from an old-fashioned kettle.

This is caused by an extreme limescale build up and if the inhibitor did not help break it down, your heat exchanger could be liable to crack at any moment and will need replacing.

5. Worcester Boiler Overheating

Diagnosis: Do the Worcester boiler fault codes you have to look anything like this: D1 286, E5 218, E5 332, E9 219 and E9 224. If so, your issue could be to do with your boiler overheating.

Cause: Normally, an overheating boiler will be caused by faulty fans or pumps. If the pumps are too hot to touch there is a chance they are seized.

Another problem can be blockages. These blockages can be caused by limescale (which can cause kettling and result in some costly fixes) or by the central heating sludge (essentially just dirty water and debris that builds up over time!)

Another type of blockage can occur in the condensate pipes. If your boiler overheats in the morning or when it is particularly cold, it may just mean your pipe is frozen. If it happens more regularly, there may be some biomass from outside that has got into your pipes.

Alternatively, sometimes, if the thermistor has failed and is unable to tell the boiler that the required heating level has been met it can continue to provide the boiler with too much fuel and produce too much heat for the water that is present.

Fix: Obviously, there are several potential causes but there is never a bad time to clean your boiler’s system out. A hot flush through or the addition of an inhibitor will help remove any loose limescale or sludge whilst a tap can prevent seizures happening in the pumps. If not, a more thorough cleaning will be required. A scale reducer and/or a magnetic system filter can also help prevent these issues in the future.

Still Unsure?

If you are still struggling with your Worcester boiler errors and our troubleshooting hasn’t provided a clear answer or solution, we recommend you book a Gas Safe Engineer as soon as possible.

PHS engineers are only a phone call away – get in touch with us today!

Related articles

Emergency Boiler Repair in Hornchurch (RM11)

A call on our 24 hour boiler repair service from a family having no heating. Our engineer responded promptly & started fault finding the reason for no heating. Diagnosed that the boiler had a seized fan motor.

Learn More
Hot Water Cylinder Tank Replacement - Woodbridge, Suffolk (IP12)

Hot Water Cylinder Tank Replacement – Woodbridge, Suffolk (IP12)

This Hot Water Tank in Woodbridge Suffolk IP12 was extremely old & full of scale restricting hot water flow, leaving the bakery flat with no hot water. Due to the age & efficiency the gas heating engineer replaced the old tank altering required pipe work & testing that the immersions where both working on the [...]
Learn More
5 Signs It's Time for a New Boiler Installation - Do I Need a New Boiler?

5 Signs It’s Time for a New Boiler Installation – Do I Need a New Boiler?

Has your boiler been acting strange lately? Then maybe it’s time for a new boiler installation. Click here to discover 5 signs you need a new boiler.

Learn More