What does the waterheater check valve's purpose?

[JPTEXAS]

2019 North Point 377. What exactly does the water heater check valve purpose? I came home from a trip that I was gone a month. Turned the water on. Flipped WH switch on. Had hot water. Next day no hotwater at any faucets. No hot water flow just cold side flowing. 20 mins later waterflow is back. Next day hot water flow is randomly on and off. Read about issues with check valve at WH. Upper hose barely warm. Tapped on valve it started to work some. I decide to remove valve and get a new one. I couldn't get the plastic valve out of the WH without fear of breaking it. So i decided to reach inside valve and gut it. Pulled oring and plast valve out. Now i have hot water. Will it hurt to leave it that way? When leave for work, OTR driver, I'm gone anywhere from 2-6 weeks. I turn off WH and turn water off. Turn propane off, just to be safe. If It doesn't hurt to leave it like this, I will.
Thank you

[JFlightRisk]

The check valve keeps the proper flow of hot water in a single direction, that is to keep hot water from backflowing. As the water heats up, it expands, and hot water is pushed back into the cold-water lines or water heater. Depending on your plumbing configuration it may or may not seem to make a difference. It does have a purpose in the system.

[craigav]

While I agree there is a purpose, the RV's I have owned ~ 2005 and earlier never used them (I am not sure what year they became common). From my information there is one on the cold water intake and another with the outlet to prevent issues when winterizing by keeping antifreeze from backfilling into the water heater. The one on the cold side keeps the hot water from backing out through the cold line when there is more pressure on the hot side. Why would there be more pressure on the hot side to back out? The answer is the expansion of the cold water when turning hot. There is reason to believe and something I commented on a while back in the forums here how the new setups with check valves allow for and can cause a much higher pressure than the lines and valves are designed for on the hot water side because the expanded water has no where to go. Without a check valve, the excess pressure is relieved any time cold or hot water is used. In the case of excess pressure on the hot side, hopefully the relief valve opens before any lines or faucets get damaged as a 150 psi relief valve is a lot of pressure... not to mention that this excess pressure due to expansion imo is the #1 cause of the relief valves leaking over time.

I would just leave it as is and see how that works for you. I would reconsider though when winterizing and especially if the antifreeze fills the water heater. I use air to blow out the lines when winterizing so the missing check valve wouldn't be an issue for myself, however it would be if I was using antifreeze... you likely could simply install a small valve there and close it when pumping antifreeze in the lines. ~CA