Worcester Bosch Greenstar 37 CDi: Cycling and noisy radiators

[George_85]

Hi Forum,

We've moved into a house with a WB Greenstar 37 CDi boiler installed in the attic and we have a few issue with the heating system, that may be interrelated:

• When CH is on, the boiler appears to be 'cycling' continuously between hot and low temperatures. It heats up to 90°, then the temperature falls to 50°, then it heats up again etc. This can't be efficient, and our first gas bill was a quite bit higher than expected.
• The radiators/pipes/TRVs are very noisy. We have the TRVs set at 2, and at this setting you we hear very loud hissing and whistling. If we set it to 1 or 3 the noise is gone.

After some research, I think it may be one (or all?) of the following:

• Radiators not properly balanced, so flow is too hot when going back to the boiler
• Max output for CH set too high at the boiler
• Pump flow rate too high

When we moved in, after bleeding and repressurising, we had this "-¦¦-" 'condensing' error message twice, but we have not seen it for 4 weeks, so I am not sure if it is related.

What are your suggestions how to pursue this? What are first steps?

Thanks a lot!

 

[kris]

Hi George . Best get a pro in to diagnose fault and repair as necessary.

 

[diamondgas]

:iagree:

Fitted in an attic!! I hope there's good access and lighting otherwise you'll struggle to get anyone interested to be honest!

 

[bigads28]

The boiler shouldn't be getting to 90C! Is the pressure gauge needle in the green?

The -][- symbol don't worry about that. It comes on if the power is turned off. If there is a board fault it can occur each time the heating comes on. It lasts 20mins and then goes back to normal, the hot water works normally through this. It's called syphon fill mode.

Sounds like you need a decent engineer to look over it and run you through its operation. Worcester have their own engineers.