Walk through the completed scope
Compare the finished installation with the accepted order. Note the model, finish, window layout and accessories supplied. If something differs, ask for the reason and have the final configuration recorded rather than relying on a memory of the conversation.
Learn normal operation
Ask the installer to demonstrate the controls and explain the relevant safety information for the selected equipment. Make sure authorized household members know where the manuals are kept. Questions are easier to resolve while the installation details are still fresh.
Keep the documents easy to find
Save the invoice, product documents and written service terms in one place. Add photographs of accessible labels if helpful. These records support future parts identification and maintenance discussions without requiring anyone to dismantle the equipment to work out what was installed.
Your questions
What if the warranty document is missing?
Request the applicable written terms from the provider. A general verbal assurance does not identify the product coverage or installation terms.
Do I need to retain information about the old door?
Keep relevant prior records until the project is resolved, especially if some existing components remain in use or a billing question is still open.