...the FW tank has its own drain.
Many of the new units are plumbed so the low point cold also drains the FW tank.
I only know this because mine is a 2018 and noticed that the cold line was plumbed this way.
Many other new units are plumbed the same way. It empties a lot faster, larger hose.
To the OP,
I opened one of the low point drains a little and water came out with possibly some antifreeze in it.
Some water came out because the dealer probably did not use compressed air to blow out the lines before they added the antifreeze. They probably skipped that step and just started adding antifreeze thru the system, allowing it to mix with water which dilutes the antifreeze. That might only be an issue if it gets really cold.
Using compressed air blown thru the system gets rid of most all residual water left in the lines after the low points gravity drain the system. This compressed air step allows the antifreeze to be the most pure undiluted protection.
You actually could drain the antifreeze back out at this point because the system is now protected and will remain so because you evacuated it of all its water, there would nothing to freeze in an empty line.
Be sure to pour some antifreeze or windshield washer fluid down each sink and shower drains. That antifreeze will sit and collect in the J-traps to protect those drains .
The winterizing idea is to protect the toilet valve, plastic faucet valves, water pump and the lines themselves, especially the elbows in those lines where residual water tends to pool (that's where the compressed air helps before adding antifreeze).
Think of your water heater as a 6 gal thermos bottle that has a drain plug on the bottom. When most of its water is gravity drained out, its protected. The small amt of remaining water in the bottom can freeze without it hurting anything. There is now so much room in that empty tank to allow for expansion, for that water to freeze and not break anything inside.
Do you know that both holding tanks for gray and black were actually dumped and cleaned ?? If not, they will freeze and maybe crack the dump valves.
As long as you are physically able and have the time (20-30 mins.)winterizing is really a very simple process and you can view many youtubes that show you how to do it. As said, out of $130, keep $124 in your pocket and you know its done right.
Photomike is closer to the real time it takes at 15 minutes. When I said 20-30 minutes I was including a coffee break .
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