HVAC bypass damper question

[James Kim]

Hi,

I'm not sure if this is the right section of the forum to post this question, but wanted to know if anyone has experienced this or have knowledge that they could share with me.

My rental unit is a 2 floor house with separate thermostat on each floor with one HVAC unit. I recently had it serviced (annual) even though the house is a new build (2022). The technician told me that i needed a 'bypass damper' that connects from the return plenum to the supply plenum. I understand that this helps with controlling temperature and air pressure in zoned spaces and the technician also told me this helps prolong the life of the HVAC.  It also appears that a bypass damper is not something that might be 'required', though i may be wrong, and I'm asking the builder if this is something they could come back to install. I'm wondering if a damper like this is really needed? or if it's just something 'nice to have' but otherwise it won't kill my HVAC early. I'm also wondering if it's required from whoever installed the HVAC system to include it as part of an HVAC system that's installed for a multi zoned (i.e. more than one thermostat) system?

Thanks in advance!

James