I use a self-built device, but you can attach a hose to your water bay inlet, run water into the hose for a couple seconds, then detach from the faucet and use a funnel to pour a cup of bleach in the end of the hose. (The water in the hose dilutes the bleach so it’s less likely to burn and damage the interior of the hose; the first time I used that method sans pre-water, an odd taste was in the tank water for weeks, likely from reacted hose material. But most people use this method of getting fluid into the tank without trouble.)
Quickly, so bleach doesn’t stand in the hose, hook up to the faucet again and turn it on to fill your tank. Run all your coach water devices until you smell bleach coming from each. Run the hot water side too; it won’t harm the hydronic unit. Let things stand for several hours or a day, then drain the tank and refill it using the same method but using a cup of dissolved baking soda in the hose instead. If possible drive the coach to help distribute the mix, and run all water devices again. Fill and dump fresh water to rinse the tank, and refill.
Make sure you include the toilet, outside shower, and any clothes washer in this whole process. You can run it through any ice maker you have, but you’d have to run several ice cycles or know how to advance the timer to flush it and any filter good. Some here will likely advise slightly different bleach and soda amounts perhaps, but for a hundred gallon water tank my suggestions have worked for me since 1985. If you feel ambitious you can make a contraption like I did to avoid bleach in the hose. I think some hose materials are just more susceptible to chemicals than others, and I find the hose method a bit clumsy.
Joel