Hello Mahmoud,
The CED describes the energy resources necessary to fulfill the functional unit of the study you are looking at. If you have a cradle to gate LCA, it will describe the energy needed to produce the boiler. If you have a cradle to grave LCA, it will describe the energy needed to produce, use, and dispose of the boiler.
CED does not directly translate to embodied emissions. To give an example, there is a large difference between 25 MJ of wind energy and 25 MJ of coal energy.
If you assume an energy source or energy mix, you can estimate the embodied emissions, but this is not a very scientific method. I would look for embodied emission data elsewhere.
Best of luck
