A diagram of a boiler water feeder is available on the Bright Hub Engineering website. Diagrams of several McDonnell Miller water feeders can be found on the BoilerSupplies.com website.
The Bright Hub Engineering website explains both open and closed water feed systems. To access the McDonnell Miller diagrams, go to the main BoilerSupplies.com website. Scroll down to the manufacturer index, and select the McDonnell Miller link. Choose the water feeder section to view the selection of McDonnell Miller water feeders. Select the Cut Sheet tab for the selected model. Cut sheets download in PDF format and contain water feeder diagrams.