The best way I can describe it is when you have an oven on clean mode, that you start smelling that metallic kind of smell.
The watchmen came and put new filters on the HVAC unit, but I still get a wiff of it for the first 20-30 seconds of the unit starting up, and then it doesn’t smell anymore. I’m wondering if whatever that smell is, is unhealthy, and what it could be?
Would getting a higher MERV filter help or is it likely something wrong with the unit?
There are so many factors that may be at play here.
How old is the unit?
Is it like the smell when a furnace turns on for the first time for the season?
Does it smell like a hot metal smell?
Do you have soot around the supply vents?
When was the last time you had your ducts cleaned?
Does the unit smell different at startup and change after running?(Not referring to the smell you are mentioning, I mean right at the unit.)
Does the unit run on electric heat, natural gas, propane, wood ect.?
Does it happen during heating or cooling?