Used Dectron unit for indoor pool

Hi all (not to worry, NOT a DIY question!) - we have a 1970-built home with an indoor pool off our living room.
It did not have a proper HVAC set-up, and started to develop some mould issues, so we shut her down until we can afford to fix it up right.
While a brand new Dectron unit is still currently out of our price-point, I have found a used unit from a house that is being completely renovated.

So, my question is has anyone here ever tried-bothered installing a used Dectron unit in another pool?

The unit is a DSH-030 5 years old - their room and pool size was a bit bigger than mine, it also has an external A/C unit with it.
My plan is to have an HVAC engineer inspect the unit, I have the contact of the engineer how "decomissioned" it (was removed Oct 2012), and then get an engineer to ensure my pools current venting design is adequate (which I'm pretty sure it is was we had an engineer in a few years ago and all windows have vents, etc).

I am a "little" hesitant about considering this route; however, he has the unit in his garage and really wants to sell it - limited market, and I'd be paying less than 1/10 of the cost of a new unit...

Thoughts? Run, I'm crazy, give it a go?

TIA for any input / advice...

That outside A/C unit is probably the remote condenser, without it the Dectron won't work. Does it also have a duct reheat unit.

At 5 years old, probably not a bad investment.

Thank you, yes, it's a remote condenser and has a reheating unit too. It's an electric system though, would have preferred natural gas, but should still be more efficient than exhausting to outside, etc.