Just finished installing propane heater in my shop, thankfully I installed ceiling fans to help move the air around. Went from dead quiet shop, to a raging loud heater. Could'nt be more disappointed, should have roled the dice and went with mini split, splits? Just felt like to many na-sayers about ceiling height. Positive note, once up to temp the heater turns off.
The "heater turns off" benefit isn't a real benefit. you're paying for delivered BTU per hour, so if you burn hard and stop, or burn low and slow, the total fuel burned is the same.
That certainly is worth mentioning. The silent heating/cooling offered by a mini-split is definitely a big upside.
Just to show i'm not in the pocket of big minisplit, you CAN get a quiet NG heater. assuming the space isn't heated all the time, an insulated cabinet 80% furnace can be hung from the ceiling. throw a duct silencer on the output with a transition and a proper filter box on the inlet and you'll eat the majority of the noise it makes, vs a bare unit heater.
Mini-splits take longer than a NG heater to raise the temperature.
that depends entirely on the size of the unit. a 60k minisplit will raise the temp just as fast as a 60k NG unit. maybe faster, since the 60k NG unit is 60k NG INPUT, and the 60k minisplit is 60k output.
for example
60k input 80% NG =48kBTU output, and your average 60k heat pump is gonna be in the 55kBTU+ output. bigger number heats faster, barring being at a temperature extreme that limits capacity - and that affects NG units too to some extent - if you're pulling 70CFM of -10F air into the shop as combustion makeup air, those leaks subtract from your net heat output.
for example:
70CFM *1.08*(65F--10F) = 5700btu/hr additional heat loss. more than an entire plug-in space heater. (note, i've got no idea how many CFM of combustion air you'd need for a 60k furnace, 70cfm is a total guess)
so that takes a "60k BTU" NG heater from a theoretical 48k down to 42kBTU delivered. only 70% of the fuel burned is functionally heating your space!
