It is possible to get your boiler repaired, replaced, or upgraded under ECO4. For a broken boiler replacement to be eligible, immediately prior to the installation the premises must have an efficient boiler, which has broken down and cannot be economically repaired. However, the ECO4 scheme includes a cap on the replacement of all efficient broken heating systems. The following measures can be installed outside of the broken heating system cap:

First Time Central Heating (FTCH)
A heating system upgrade
A renewable heating system
A district heating connection
An innovation measure
The installation of heating controls
Heating system upgrades (which are not capped) can only occur when the existing boiler is inefficient (non-condensing), otherwise, the boiler is instead eligible for a replacement subject to the cap. See Chapter 5 of the ECO4 Guidance: Delivery document for more information on eligible boiler measures.