Is there any room within the slimduct unit for a heater? The unit looks exceedingly small. If Fujitsu doesn't offer a heating strip for the unit, I doubt that one can be added safely. Heating strips need proper airflow so localized areas of the strip do not overheat and fail or start a fire; I doubt there is sufficient room within the slimduct unit to straighten out the airflow for a heater to be added.

The rep from fujitsu said they have a connector kit that plugs in and can be wired to an auxilary heater and he said they do sell heaters but cannot recommend one as a homeowner. But I don't even see any fujistu auxiliary heaters anywhere online but when I bought the units I was told I won't need them but it was an option?

UTD-ECS5A that's part number for connector kit for auxiliary heat and other functions for use with slim

Additions/options may only be available from a Fujitsu contractor, some companies do that.

Which is fine I just wanted a catalog to get an idea..I just want as factory fit and safe as possible. If I can't get that I won't do something that's not meant to fit or be a risk. I will contact the supply house where I got this system from and see my options if

It sounds like as would be expected when contacted by a home owner (and not an HVAC pro), Fujitsu is being politely evasive. They don't want to encourage amateurs to buy and install their equipment. I'm not sure why some of these companies even sell to the online equipment sellers who bypass licensed and trained HVAC contractors - in many such cases, the equipment is NOT covered by a warranty so maybe that's a way of saying to DIYers - "you're on your own".

I'm not surprised by your experience. Hire a pro to (hopefully) have the job done right but if not, to have the work covered by a warranty.

Amateur here:

1. There is not heat strip for the ARU12RLF. Specs, Technical Manual.
2. The UTD-ECS5A wiring kit can be used for a variety of purposes as described on the web page.
3. The Installation Instructions (page 4) indicate that it can be used to control an auxiliary heater when that heater shares duct work with the "indoor unit" which I presume to be the ARU12RLF.
4. My presumption is that the ARU12RLF doesn't have duct work based on the pictures in the Technical Manual of how it is typically installed in a house.
5. You could just buy a couple of electric space heaters for use when the Fujitsu system was insufficient.

With a 1 year old thats not as ideal. And it was installed by a licensed nj HVAC-R master tech.