Worcester bosch 400 overheat trip

[cambers]

My worcester bosch 400 keeps on tripping out on high temp after about 10 secs. A few weeks previous I noticed the fan was slightly noisy but It is still turning ok. Are these problems related, I have also noticed the domestic hot water is really hot.
Any ideas?

 

[Agile]

You dont say if this is on CH and HW on jusyt on HW only.

Obviously an engineer would do certain checks but the immediate suspect would be the system flow rate and the temperature sensors.

The engineer might check the setup of the gas valve first to ensure that is correct before looking for a fault.

Tony

 

[ChrisR]

Pump?

 

[cambers]

Pump is running ok , noticed the heatbank is cold, boiler trips on both CH and DHW. System has had no problems with flow rate etc for the last 5 years

 

[ollski]

Sludged up dhw heat exchanger, or possibly if you are very lucky the filter in the top plastic manifold block. After about 6 years these things drop like flies to sludged hx's.

 

[cambers]

Thanks for your help guys, I noticed between trips that no matter which speed selection I chose on the pump it was running at the same speed, very very slow. Pump removed, new one installed, wife now has hot water and I am the best husband in the world. (wonder if I will be allowed to watch the football).