Water check valve locations

[NYSUPstater]

This will have to be done next spring, but I may have water check valve(s) bad between the bypass/diverter valve and hot water tank because antifreeze was going into HW tank. Learning something new after 15 years at this so where would they be located? This assuming the diverter valve is okay in the 1st place and the check valve(s) (if any) are bad.

I do have to mention that IF the check valve(s) are bad, I may have caused this by blowing out the water lines w/ air 1st. This is what I did:
1. Drained water tank
2. Put drain plug back in after I heard air going into tank thinking it needed to be pressurized to force any water in hot water lines out
3. Attached air adapter and air line, set to 35psi
4. Opened all water lines after numbers 2 & 3
5. Attached siphon hose for AF, flipped bypass lever, turned Anderson valve to "Winterize"
6. Turned on water pump and this is where I discovered AF going into water tank cuz pump ran for a long time sucking up AF when it shouldn't have
7. Figured it was a fluke, switched to another jug of AF only to find out AF still going into tank. Talk about a DA I am!
8. Drain AF out of tank only to repeat it after DA me put it right back into water tank!
9. So after all this and thinking diverter valve is bad and having to get rig winterized by today, I ended up disconnecting the cold/hot water lines at water heater, attaching a hose to the ends, bypass valve engaged and proceeded to add AF to which all worked.

So I found a new diver valve online should that be bad, but if a check valve is the culprit, due to my being dumb, just need to know where they are and how many.

 

[danemayer]

I had a similar experience where after bypassing the water heater, antifreeze went into the water heater tank. I also assumed it was the bypass valve failing. At the national rally, as one of my repairs, I asked the factory team to replace the bypass valve. Guess what, that winter, I still got antifreeze in the tank. Turned out it was a stuck/broken check valve at the water heater hot outlet.

 

[NYSUPstater]

Well a year later, 1 valve replaced this past spring (albeit a plastic one) on HW tank, followed directions on label at docking station...........and WHOLLA NO probs winterizing it this year and NO anti-freeze going into HW tank !!!!! Still have orig A-valve. Didn't blow things out, but made sure plenty of AF went into the lines. Happy Camper!!!!!!