There are too many drunks answering, I thought I was bad !
24 volts is normally used simply where you expect better safety. in case the bare sections of the wires come in contact with the elements, and with your skin while working with it.
the power consumptions ( watts ) to energize a device is irrelevant of the voltage, with higher voltage you use less current, therefore a smaller diameter wire, and vice versa, ever wonder why your 12 volts starter cable is so huge on your lawnmower, compare to the electric start wires on a snow blower ?
So a good analogy to a part of your question is the following : " I have a snow blower with the option of installing an electric starter, should I use 110 volts one, or a 12 volt one ? "
Higher voltage is better for a farther distance . "That's why power is carried across country on high voltage wires "
The rest becomes availability, and what's practical, device cost is mostly based on production runs.
coaledsweat wrote:The 24 volt allows for it to run more devices.
Does that mean I can not turn on all my 110 Volts lights at home at the same time ?
Freddy wrote:I vote for: Unless you NEED 120V, use 24V. They are cheaper, use less electricity, and if you have a short circuit, they throw less sparks.
For the same amount of power output ( P=V*I ) 24 volts does not use less electricity, in fact it may use a tiny bit more !
steamup wrote:Also, 115 volt thermostats are poor control devices. Plus/Minus 1 deg F at best, sometimes it takes 2 deg. F. to actuate them.
24 volt thermostats are more available and more precise devices. Even the old style thermostats had heat anticipators in them that would help with more acurate control.
24 volt is my choice unless I am controlling a 110 volt fan directly such as for a garage unit heater where comfort is not a concern.
I guess you haven't been keeping up with what out there, there are plenty hi precision 110 volts digital thermostats , the Win 100 by LUX is one and it retails for under 50 Dollars