"Stuck" Bypass valves in 1995 PW ....

[mamello]

Before winterizing, I attempted to close the 2 bypass valves(see photo below...one at the cold and one at the hot..grey, metal "half wing" handles) in our (new to us) 1995 PW and discovered they would not turn. I unscrewed the handles, took them off, used different lubricants but to no avail. Since the previous 2 owners always kept this PW in heated garages, I suspect they had no need to winterize or use the bypass valves. My guess is that they have corroded over the years and are now "corroded/stuck" in the open position.
My question:
Is there anyway to make these work again short of taking the assembly all apart?
Logically I am wondering why there are 2 bypass valves. Would one bypass valve not do the job of keeping the antifreeze from going into the hot water tank?
If I left the original bypass valves as they are, in the open position.... and put in a new bypass valve in the center of the white hose (that goes between the 2)..........is this a good ? Is it doable?
Thoughts? Advice?

[LesM]

I have the same model/year PW, and I just winterized it last week. My water heater bypass arrangement is identical to yours and I have similar problem with the valves. They did turn; they were just incredibly stiff and the "handle" length doesn't give much leverage. I could not turn them by reaching through the front access door panel; I had to lift the seat and reach down from above - allowed me a little more leverage. I was going to use a pair of vice grips on them, but with a lot of effort (tough on the thumbs) they turned.
The previous owner of the van (I bought it a year ago, so this is the 2nd time I've winterized it) did use a short separate bypass. It's a length of tubing (about the same length as the installed bypass line) with an elbow and female fitting at each end. He just disconnected the in/out lines (grey tubing) from the bypass valves and connected them to this temporary bypass, leaving the heater (together with the problematic valves and the white bypass line) totally isolated from the water system. I don't think a single valve in the white bypass line would actually accomplish anything, but the above method works very well. I think I may have even seen such bypasses for sale at RV dealers.
As an after comment, he (previous owner) was also concerned about mice getting in the van, and he would wrap something over the inlet and outlet of the heater to prevent any possibility of a mouse finding its way into he heater (although I find it ard to imagine a mouse squeezing throughn one of those valves).
Hope that helps. I may use his system next year, particularly if I have same problem with valves in the spring...

Les

[mamello]

Thanks Les. That was very helpful. I will try again with some vice grips (my thumbs are too sore from trying!)to see if they will turn. If not the short separate bypass you describe could do the trick I am sure.
Cheers,
Mamello