I have Hydronic heat with a NG boiler. Brennen did a good and professional job when it was last replaced and updated. It is a low pressure hot water circulation system so any plumber or layman with soldering skills can extend or repair the actual piping and baseboard radiators.
This is not a widely used system but they were knowledgable and appeared factory trained. They have their own electrician to do the electrical connections and it was all done in two days.
http://www.brennanheating.com/about_01.php
I have had no contact with them other than as a customer.
