Navien 180 ASME GAS COMBO Boiler/Hotwater heater / Carriage house?

All,

i am renovating a lofted one bedroom space maybe 600 sq feet above 2nd floor of a carriage house. i want to purchase this unit but i am worried it may be "too big" for the space?

i would use it for baseboard heat and hot water... would there be any downside if it was too big? it says min output BTU of 17,000k... I dont have a lot of knowledge about this and need some help.

I need to use gas as a i dont have enough electric for baseboard heating, i like the idea of on demand because i dont know how often i will actually be using the space of it i may rent it or what.

thank you
Peter

Without a heat load analysis, you won't know what you actually need, but 17K is probably 2-3x more than you need except on the coldest day of the century (this is a guess). Keeping the unit hot 24/7 to provide hot water is also a waste. There probably isn't a boiler sold here small enough for maximum efficiency, but a mini-split system should be able to handle it fairly easily along with a gas WH.