From what I understand the legs are removable and a person I talked to on craigslist had his directly on the ground. Which I would think you would want some air gap between there but I guess it worked for him. I plan on fabbin some 3" legs and it will work out great height wise.
This might be ok if this was going into a masonry fireplace directly on the fireplace floor. But that's not the case. You have a ZC fireplace which means that you don't have 6 ft of foundation brick sitting under this thing. You have a hearth sitting on a wood floor. That's a combustible hearth.
Check the manual. It only allows no legs in a masonry fireplace. As far as I can tell it does not allow connection to a ZC fireplace even with the regular legs, though I might be comfortable with that if the hearth requirements were not compromised.
Fireplace Installations
You may install your Dutchwest Convection Heater in
an existing fireplace as a fireplace insert with no legs,*
or with the standard legs attached.
To install the heater without legs as a fireplace insert,
the floor must be completely noncombustible, such as
an unpainted concrete floor over earth.
Many fireplaces do not satisfy the “completely noncombustible”
requirement because the brick or concrete
hearth in front of the fireplace opening usually is
supported by heavy wooden framing as in Figure 13.
Because heat passes readily through brick or concrete,
it can easily pass through to the wood. As a result, such
fireplace hearths are considered a combustible floor.
You may not install a heater on a combustible
hearth without legs. Standard leg installations must
include the bottom heat shield. The floor protector
must also meet standard requirements for freestanding
installations.
Important: Failure to follow these installation instructions
may result in a dangerous situation, including a
chimney or house fire. Follow all instructions exactly,
and
do not allow makeshift compromises to endanger
property and personal safety.