How to get hot water to the sink

Question edited to add MAKER and add (what it is).
Question moved to correct category.

Sounds like a water pump issue? Can you hear it?

https://www.google.com/search?q=2022+Forest+River+Georgetown+34M5+RV+water+pump

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The first thing to do is to drain the fresh water tank. Drain the hot water heater. Install the RV antifreeze by allowing the water pump to be pumped into the water lines by opening the valve for this process. Open each water valve on all the sinks and the toilet valve as the RV antifreeze is being sucked into the water system and run until the color changes to the color of the antifreeze. Allow each trap to have antifreeze in it also, sinks, shower drain etc. Remove the inline water filter if one is installed and install the bypass plug in its place.

I actually am not able to get rid of the antifreeze taste from the water system so I blow air into the hot water tank drain at a low pressure until all the valve at each place water is controlled. Do not forget the outside sprayer and the shower hose and the shower head.

I allow the pressure to build up to 20 psi or so and then go into the unit and open each faucet until all the water is pushed out of the lines. Then I dump antifreeze into each P trap. Do not use the antifreeze used in the engine cooling system but the non toxic type made especially for RV water systems.

The galley holding tank holds the grey water from the galley.

You'll probably have to crawl under and trace where they go. You could possibly put some dye in one of the grey water tanks (ie: the kitchen sink drain or bathroom sink or shower drain) to figure out where it comes from. The black tank is your toilet drain. It always has the larger diameter pipe going to the valve (usually 2 or 3 inch diameter) The grey water tubing is usually 1 1/2 inch tubing.

Check by-pass valve(s) position on back of tank.

If it is a big valve it is your sewer tank drain valve. There is two valves. One is the Black water drain and the other is the gray water drain. the black water drain comes from the toilet holding tank, and the gray water valve drains the shower and sink holding tank.

need to check connections going to shower. turn on water and see if runs down lines. also try to reach up to the sink connections a do the same. they tend to come loose. should be able to hand tighten. also check behind toilet at connection.

Most class a mtorhomes have water valves in your water fill bay that have controls for all faucets. There is separate one for hot and cold.
the hot would be turned off for storage to allow you to drain the hot water heater for storage.
there may be hot water valve for all faucets or one valvefor each faucet.

Comes off the top of the water heater and is routed to the bathroom sink, the kitchen sink, the shower/tub, outside shower and washing machine (if equipped).

Make sure you have enough water in the tank or city water hooked up. A pump will run and suck air if the level is low. it could force water to the sink, etc, but not the shower.

Are your valves for the water pump set correctly? Remote possibility someone installed a shut-off valve between the pump and shower.

Could be the pump is getting weak/leaking internally and can't build enough pressure.

Make sure the shower head is not clogged. Remove it from the hose and try again.