How to properly install a backflow check valve on a hotwater heating system

Hi Tazman...

What kind of backflow check do you have? Is this regarding a 1/2" copper WATTS 9D backflow preventer (see image)? If so, this needs to be connected into the water supply just before the pressure reducing valve.

Most likely, there will be a shutoff just before the existing pressure reducing valve. You may need to drain the boiler system to install the new backflow preventer.

When installing the new backflow preventer you want to install 2 shutoffs so that you can isolate the pressure reducing valve and the backflow preventer and keep from needing to drain the boiler in the future should one of the valves fail... ;)

Let me know if you want to discuss more...

MARK