Hello, can anyone tell me how many gals of antifreeze I must add for two 500 ft wells with 1 1/2 pipe.  My contractor is getting two diffenent answers.   One says 55 gals the other says 120 gals.  Turns out my well guy didn't put the antifreeze in.

the way I have always added to a system is to measure in water . get that gal. divide by 2 and pump out the water as you pump in the required anti-freeze . Re purge and allow the pump to run for a while to mix the solution. test for freeze protection

But Im sure somebody here knows a math formula to tell you without my additional steps

If you have 2000' of 1.5" pipe, the total volume is 192 gallons. 20% methanol will give you freeze protection to 15°. That would be 38 gallons of methanol.

Thanks for the replys, I agree we decided on 40 gals.  I will have to live on strip heat until next Wednesday when they can come and purge the system.