This relay mounts inside the HE440 control panel. There are 4 of these relays inside the control panel. The relay is a SPDT switch and the coil is energized with 24 vac.
To test this relay, connect 24 vac to the coil terminals. The coil connections are the smaller 3/16" quick connect terminals. Check continuity at terminals labeled; com, nc, no. Terminology is common, normally open, normally closed.
These 4 relays are referenced in the schematic as R1 thru R4. The schematic is on page 11 of the HE440 Product Data manual.