Worcester Combi 28i

[JimmyDean]

My boiler recently packed up a couple of days after I had repressurised and bled the rads due to the pressure having been very low without me realising. I now have no hot water and no central heating. A friend has a had a look at it and he tells me that something is causing the fuse to blow internally when the system is turned off, i.e. when the hot tap is turned off. He has changed the fuse a couple of times but the same thing happens. The system is about 3 years old and was regularly serviced until about 6 months ago. The pump is working and the pressue is between 1 and 2. However, leading up to this I did appear to be losing pressure gradually. I have no experience with boilers, I have no hand book and I would be grateful for any help. Many thanks.

 

[ollski]

check it isn't an internal leak dripping onto electrical components.

 

[JimmyDean]

Thank you. There does not appear to be any leaks. The only water present was that which came from the pump valve when I removed it to check the pump was working. It is now dry again but the fuse is still blowing. Any further suggestions will be gratefully received.

 

[ChrisR]

Just about anything CAN blow fuses. Chief suspects are (after anything damp) the pump, fan, motorised valve(s) and gas valve. Normal procedure would be to disconnect from these, change fuse and switch on - see if it blows, reconnect one at a time and so on.
On the last fuse-blower I went to it was the overheat thermostat, which is just a switch, but it was shorted internally to earth though it showed as an open circuit on a multimeter.
You can do this sort of investigation yourself if you're it doesn't involve taking the case off the boiler. Dont do any connecting live!

 

[JimmyDean]

Thanks again. I will try that this evening and let you know how I get on.

 

[ChrisR]

As you had an empty system, check that the autimatic air vent hasn't started to leak a bit. Note sure if yours is on the pump or top of the boiler.