Dear :

I am very grateful that you sent [name] to install the for us. You are indeed fortunate to have such a highly qualified and dedicated engineer. He accomplished a difficult job with rare expertise and took great pains to ensure that everything would work in perfect order.

I have told [name] how much I appreciate his professional service, but I wanted to tell you as well. I would be delighted if you could include this letter in his personnel file.

Sincerely yours,

[name]

[title]