GB Boiler – Frost Damage Flow Chart

Morco have assessed a number of damaged hydroblocks and established that currently there are 4 main areas of frost damage. Please see the photos below. If an engineer is unsure as to which areas are broken and cannot identify them, the only way to guarantee a successful repair is to replace the entire hydroblock. Refurbishment can subsequently be carried out on the replaced hydroblock using the return group, flow group and heat exchanger kits. The hydroblock can then be used again.

Please note the below photo may not reflect yours exactly if you have a boiler with s/n beginning AFN or AGY

ICB132001 – Hydroblock 24kw AAZ & ACH
ICB132002E – Hydroblock 24kw ADP, ADH & ADM
ICB132003 – Hydroblock 24kw AFN & AGY
ICB132300 – Hydroblock 30kw AAZ & ACH
ICB132302E – Hydroblock 30kw ADP, ADH & ADM
ICB132303 – Hydroblock 30kw AFN & AGY

If the base plate is damaged as shown above, then it may be impossible to straighten out and Morco do not supply it as a spare part. A new hydroblock is the only solution in this case.

If there is any distortion in the areas labelled above then it can be safely assumed that there is internal damage. This will result in the internal waterways for the primary circuit being narrowed or blocked and will give problems with the safe and efficient operation of the boiler. It is entirely possible that, even without external distortion, that there is internal damage. Morco do not supply the specialised lip washers separately.

This shows the damage caused to the flow regulator/cold water filter.

If an engineer is absolutely sure they know which components are damaged then the following sets are listed:


ICB119001 – Return Group Kit (GB24 and GB30) AAZ, ACH, ADP, ADH, ADM, AFN & AGY	ICB121002 – Heat Exchanger Kit (GB24 only) AAZ, ACH, ADP, ADH, ADM, AFN & AGY
	ICB121302 – Heat Exchanger Kit (GB30 only) AAZ, ACH, ADP, ADH, ADM, AFN & AGY