Boot menu gone after installing Windows 7 from recovery partition


So after a quite convoluted Windows 7 install (via DHCP/TFTP) on a machine that has no DVD or USB I've decided to install EasyBCD and make a recovery partition, so that I can reinstall from the machine itself if it's needed.

This is the partition layout:

No letter - System - 100 mb (the partition created for the System by the Windows 7 installer), Primary
C - Windows 7 - 30 GB, Primary
No letter - Windows 7 install - 10 GB, Primary (not mounted to avoid changes to it)
D - Workspace - 120 GB, Logical (work files)

So, to test this recovery partition, I've booted from it and re-installed Windows 7 again on C. Everything went fine, except that, after the install, the boot menu is gone and it boots to the new Windows 7 installation without prompt. I could recover the menu by installing EasyBCD and adding the entry again.

Now the question is... why is this needed? Could it be because during the Windows 7 installation I deleted both the System partition and the Windows 7 one? Should I leave the System partition alone and only format the Windows 7 (C) one if I need to reinstall in the future?
When you install Windows, it will create a single entry BCD (no boot menu) on an empty system.
An "empty" system is one where the setup program cannot see an "active" partition already existing.
By this means, you can (as I have done), install XP, Vista, W7 and W8 on separate partitions without any auto-dual-booting, where each partition contains its own boot files and no reference to any of the other systems, by the simple expedient of setting the new partition "active" as you start each installation.
In your case, you deleted the active partition containing your customized BCD and created a vanilla new one with the install.
You could try backing up the BCD into your data partition then restoring it after the install (provided the position of the partition is identical)
Thanks for the input.

> You could try backing up the BCD into your data partition then restoring it after the install

I've did that, the partition layout will be identical across any re-installation anyway.