2013 RZ2 Cross Vent/Drain

[Tulsah]

I am considering upgrading to the MLA custom RZ2 sacs in my 2013 RZ2. While in there, it would be a great time to do the cross vent/drain mod as well. That said, what is the current consensus on the addition of check valves into these lines at the same time? I've read a number of threads from the past where it was about 50/50 as to whether they provided appropriate benefit. If it provides some help, I'm not opposed to it. My boat already has factory check valves in the fill lines. Thanks in advance.

-Tulsah

[Stingreye]

My vote is for check valves on at least the vents.

It helped drain my bags more fully and raison up more even though I use aerator pumps. If your vents and drains share a thru hull, the check valve on the vent keeps the drain from recycling back through the vent.

Mike (MLA) helped me out with my setup and it works great.

Regarding drain check valve, its not necessary on my setup but I curious about other opinions on check valves on the drains.

One question, can he use the check valve as the hose extender (instead of a barb) or does the check valve need to be in a specific orientation/position?

[mnpracing]

I am considering upgrading to the MLA custom RZ2 sacs in my 2013 RZ2. While in there, it would be a great time to do the cross vent/drain mod as well. That said, what is the current consensus on the addition of check valves into these lines at the same time? I've read a number of threads from the past where it was about 50/50 as to whether they provided appropriate benefit. If it provides some help, I'm not opposed to it. My boat already has factory check valves in the fill lines. Thanks in advance.

-Tulsah

I would not use a check valve on the vent for the tank, as the tank needs a way for air to replace the water as the tank is being drained. I put check valves on my drain lines, probably could have done without.

[Tulsah]

One question, can he use the check valve as the hose extender (instead of a barb) or does the check valve need to be in a specific orientation/position?

If I go with checks on vents and/or drains, I would use them in place of a barbed coupling to make the splice to the extended hose.

[Ewok]

As always on these threads, the correct answer is, it depends. It depends on how the upgrade is accomplished, just swapping out bags or adding additional pumps for the bigger sac? If keeping the factory plumbing, and just swapping out the bags, then I would put a check valve on the vent line for the sac. There should be an additional vent line for the hard tank in the factory configuration. Anything else, then it's all dependent on how the plumbing is run and if any tanks/bags share a vent.

Either way, I don't think a 1 way check is necessary or helpful for the drain line of either the hard tank or the sac.

[Tulsah]

As always on these threads, the correct answer is, it depends. It depends on how the upgrade is accomplished, just swapping out bags or adding additional pumps for the bigger sac? If keeping the factory plumbing, and just swapping out the bags, then I would put a check valve on the vent line for the sac. There should be an additional vent line for the hard tank in the factory configuration. Anything else, then it's all dependent on how the plumbing is run and if any tanks/bags share a vent.

Either way, I don't think a 1 way check is necessary or helpful for the drain line of either the hard tank or the sac.

Thanks Ewok. I'm still working at tracing out all of the lines in the system. It's presently equipped with the factory pro system. My intention is to simply replace the factory rear sacs with the larger ones from MLA, then cross vent and drain. I believe that the factory tank and sac share a common vent, common fill and common drain. The order/arrangement of the fill and drain are still under investigation ...

-Tulsah

[chpthril]

As mentioned above, if a c/v is used in the vent line, it absolutely has to be between the sac and the T fitting where the hard tank's vent line comes in. The tank has to vent freely. A c/v in theory, could be placed in the drain line, but it would reduce the drain flow. In my experience, crossing the drain line is better then a c/v. We also see most of the passive draining through the drain line. Passive draining through the fill line, seems to be hit and miss from model to model and even boat to boat with in the same model. I think this is due to being hand built. A slight difference in how that fill line is routed, can make that difference.

[Tulsah]

Ok, so I had a chance to dig around and trace out all of the lines. It turns out, I only have factory check valves on the bow sacs fill lines - I assume the factory only installed these to counteract potential gravity draining due to typical bowrise? The rear sac/tank arrangement has no factory check valves of any sort. The fill pump wye's off to fill both the sac and tank simultaneously, but the sac will pass water through to the tank through two lines until the tank is full. Both the sac and tank vent are wye'd together to share a common thru hull. The drain pump appears to drain from the tank only as the sac gravity drains to the tank.

With this known, I guess the best would be to add check valves after the rear pumps (before wye) and then simply cross vent and drain the new larger sacs.

I measured the OD of my hoses to be approximately 1.37". Would I be correct in assuming that this would be 1.125" ID hose?