Example of how to pipe a Hydronic Radiator or Fan Convector with a Mono-Flo Tee. The Mono Flo tee will force water up into the applicance.
You will notice how the distance between the Mono Flow Tee and regular tee is about 12 inches or more - this is important. Also the Mono Flow Tee is on the return. In some cases you will need two mono flow tees for installs that are a long way from the pump - see more info on this on the mono flo buy pages.