We have a 40 year old house with hot water heating (baseboard). We asked Lambert (who had installed the system originally) to come and evaluate it, since it seemed noisy to us, and to install digital temperature controls.
The service man came, and gave us a very informed and honest opinion, that our system, while old, was working well. He said that the noise was coming from the pipes, and not the heating system, and that the pumps we had were probably of better quality than what we could buy today.
He then educated us on how to most efficiently use our type of home heating, and told us that we probably wouldn't get any benefit from installing the digital temperature controls.
So in the end, we learned a lot from him, and spent a lot less money than we had feared.