Before we moved to Arizona for our winters, I used to use the water pump to push RV antifreeze through all the piping in the coach. Blowing out the water with compressed air will result in less antifreeze needed because the antifreeze won't get diluted as it mixes with fresh water during the procedure. I remove the IN pipe from the water pump and attach a few feet of clear tubing to the water pump using a proper size fitting. After putting several gallons of antifreeze into a bucket with the other end of the clear tubing in the bottom of the bucket, turn on the water pump, go inside the coach, and turn on each faucet until the RV antifreeze comes out and runs the same color as the antifreeze in the gallon jugs. Do both the hot and cold sides of each faucet, shower, and clothes washer, probably best to do the hot first to be sure the water heater (AquaHot, Hurricane, etc.) gets completely filled. Don't forget to flush the toilet until antifreeze goes into the bowl. It's an easier job with two people, one person in the coach turning faucets on and off, and another person adding antifreeze to the bucket.
