Propane tank question

[raddksn]

I will be changing my propane supplier after this season, so I don’t want a 200 gallon minimum delivery. I currently have a 500 gallon tank that is at 10%, unfortunately it looks like I need to run my heat for longer than the 10% will last.
My question is, can I hook up a 100LB tank when I exhaust the 10% to get me through?
There is a regulator on the tank and another one on the house. This confused me, why two regulators? My background is electrical not gas!
As always, thanks in advance for any advice or guidance!

 

[The Cobbler]

you should be able to run it off a 100lb tank as long as you're not drawing too fast & freezing the tank .
the 2 regulators are primary & secondary, the first one brings the PSi to about 10 psi , then the second brings it to about 9" WC ( water column) . it allows for smaller piping to be used between the regs