Hooking up directly to hot water tank

Well...........

With trailer that gutted/open I would get rid of that gray Polybutylene pipe and start new with 1/2" PEX and run cold water lines to all fixtures and then hot water lines to fixtures.
Sharkbite fittings can be used or FlairIT (by SeaTech)


Water heater plumbing (this one uses check valve in Hot out---I would NOT use check valve. I would have a shutoff valve in hot out (cold in and bypass---3 valve system)

Hot is out at the top connection and cold comes in the bottom. Easy way to remember it "heat rises". Like westend say's, add the by pass so Old Man Winter won't be leaving you extra projects for the spring time.

I can't make anything out from those pictures of pipes other than your water heater is disconnected. You should be able to reconnect the pipes to the water heater by matching the existing pipes to the cutoff pieces in the water heater (you have one short and one long stub on the heater-the corresponding long-short should be the opposite with the inlet piping).

If they don't correspond, the heater has an inlet usually with a "tee" from the cold water. The outlet will be a single pipe to the hot water side of your plumbing fixtures.

Note: this would be a good time to install a "bypass kit for winterization", basically three valves and two tees. Search the internet or CW for the kit to see how this fits into the plumbing system.

Tools: If you buy Sharkbite fittings, you won't need any tools besides a pipe cutter. If you use the flair type fittings, you'll need a pipe cutter, a wrench or a channel lock pliers to tighten the fittings.

Good luck with the plumbing.