The all in one design of the high efficiency boiler with optional water heating results in considerable cost savings! Equipped with a variable speed power cable feed and variable speed motor. The latest the plumbing daily! The recognition has also generated additional business for the plumbing contractor. Their work is superb but i wish they had disclosed that the hourly rate was for only one of the plumbers and not both ended up having to pay more than i expected their work is solid! We are responsible.