That was standard practice on our old Pace Arrow that had an open access water fill port, at least for sterilizing and then sodafying things. For winterizing we just opened faucets, toilet valve, and the main drain to clear lines, then blew them out with compressed air.
But on Monty Rae it’s more important to protect the hydronic unit and perhaps an icemaker valve, and washing machine via a cup of antifreeze in the washer drum and one rinse cycle to protect the pump. Blowing the lines is easy enough, but unreliable when it comes to certain components like the icemaker valve and especially the hydronic unit, where a tiny bit of trapped water can cost thousands in repairs. Simply disconnecting the icemaker valve line or depending on its heat tape has proved unreliable also, so when winterizing I also cycle the icemaker until antifreeze shows at least on the output side of the valve if not the ice tray.
Getting back to your question, I don’t see why you can’t add antifreeze to the tank. However, our large tanks would seem to me to require a lot more of the pink stuff just to reach the tank pickup, much less then fill the lines. Later, when dewinterizing, it’d be trickier to save fluid for future use, via the tank drain (yeah, some of us do that, albeit via the faucets back into original containers). You’ll also have to take time to thoroughly rinse the tank.
It would seem easier overall to just use the existing diverter system, and it would use less antifreeze. 6 gallons likely will not be enough in the tank to allow for the amount needed before the pickup can get enough fluid to fill the hydronic unit and all spigots. And you would have to waste any dumped from the tank next spring if you didn’t go to the effort to catch drain effluent.
Joel
