i mean technically, you could use it but it sounds gross to do without a filtration of some sort before it goes to whatever storage you’re referring to.

another thing to note is that most baseboard heaters are OK to use on 12 AWG. If you’re tight on space in your panel, you’ll likely free up 2 spaces in your box eliminating the heater but still will need to run whatever gauge wire is suggested in the installation manual. (if i’m understanding your intention of removing the resistance heater)