returning dvr’s

We can’t answer for sure. They will probably want the HR24. They’ll let you know when you cancel. 

The HR20 is definitely not wanted back by DIRECTV. That receiver is ancient and underpowered for today’s software.

The HR22 is also an older box. I doubt they want this back either. 

They may want the HR24 back as litzdog911 says. They have a low stock of HR24s so getting them back via returns is likely their way of restocking.

Do be aware that DIRECTV may just want you to drop all of them off at UPS for two to be recycled (by DIRECTV) and the HR24 to be sent back to the receiver distribution center.

The HR20 and HR22 have been non-returnable for years.

HR24 supposedly is non-returnable. Even though there isn't a newer model regular HDDVR, it can use the older multiswitch and is on the previous software. Pretty much DirecTV went hard into Genie-only setups after AT&T acquired them.

You can at least try returning the HR24 to a participating FedEx/The UPS Store after you cancel. Bring the other two boxes just in case. There have been reports they have accepted older models, so perhaps they are trying to do an in-house recycling program now.

You can, however, disconnect the HR20 from the satellite as well as Internet before cancelling so that the access card won’t receive the kill signal.

Do notice, however, that the HR20 requires a frequent update from the satellite. If it doesn’t get the update, the HR20 is rendered useless and nothing will work. This period when the HR20 gets cranky (wants an update from the sat) could be hours, days, weeks, months, or a year. For my DVRs I have had so many different scenarios.