Any Electricians?

[SideShow Bob]

Your link is not working for me, if the heater is rated for 30 amps or less at maximum load, you can run it on the existing circuit. But you will have to eliminate the plug or put a male cord end on the heater. This will prevent you from inadvertently runnining both a welder and the heater at the same time and having the breaker trip and or over current on the wires to the plug.

That will be $25, please......

Edit:
I don’t have access to my NEC manual, you will need to find out if a garage heater is considered a “continuous use devise”. If it is, you will have to up the load rating 125%.
Then see if the existing wiring size is rated for that load.

That will I’ll be another $25 please.

Edit 2:
Article 424, the section that deals with electrical heaters, considers a fixed electrical heater is a continuous use appliance. [424.3(B)]. So you will have to use the load calculation factor to determine the proper conductor size and over current protection.
Also, you cannot by code you will not be able to install a male cord end and use the existing plug.

That will be another $50.......... I had to actually use my brain, and a finger to turn pages....