Fill thru hull/empty above water with rev. pump?

I have been searching on here and cant seem to get a clear answer. Looking redesign the ballast system on my 2001 SAN. Question is if i got with a pair of jabsco reversible pumps, how can i fill using a thru hull and empty above the water line? Similar to how MC does. (http://www.wakeworld.com/MB/Discus/messages/65921/217365.html) What type of check valve system can i use to mimic that?

(Message edited by liquiddiet on August 04, 2009)

Two of them, one on the fill line from below water line, flow direction to pump, then one on the empty line, flow direction to the thru hull. Put them both to a "t" then a single line to the pump barb. When in fill mode the fill check will open and the empty will stay closed from the suction, then in empty mode the fill check will close forcing water to the empty side. Hope that helps, I like the whale or guzzler check valves because they are servicable if something makes it's way in, you can take them apart and clear it.

well what about when you are trying to empty while on way? Wont the pressure from thru hull open lower check valve?

Are you using a scoop style thru hull? If so than yes.

yes using factory scoop type. I'm thinking it might be a better idea to design with 2 aerator pumps per bag

Yes it will open the check valve, but it wont push through the pump, so it does not matter. I made this diagram a few years ago, it is of the old MB Ballast system.

so valves like these would work? http://www.wakemakers.com/check-valve-fitting-1-inch.html

Those look fancy, expensive, and serviceable. I would make sure that they are super air tight, especially when you are talking about "below the waterline" fixtures and fixtures that are relying on a vacuum to work.

These look cool, might not be once the algae starts building up.

http://www.clearpvcpipe.com/index.asp?PageAction=VIEWPROD&ProdID=183

Those whale valves are exactly what I have, only mine are 3/4". I've had no problem with them, used in saltwater 100% for three years now.

Use a mushroom thru-hull and the sacs wont be force-fed while under way, system works great.

Ryan-

If you use a scoop type fitting and aerator pumps you will have problems with the bags filling when the boat is running. There's really no way to prevent that unless you use a solenoid valve, which is either incredibly expensive, or will severely limit flow.

If you want to use aerators, use a non-scoop style intake; if you want to use a scoop intake, use reversible pumps.

Check out the post I just put up on the basics of designing a system using a reversible ballast pump for more information.

We've selected the Whale check valves after looking at everything else for a number of reasons:

1) They work in any position (most swing type check valves also function that way, but not all).
2) They check against water AND air, which makes them popular in reversible systems for people that want to completely empty their bags.
3) They require no maintenance and contain no parts that can become clogged or blocked due to debris.
4) They don't block any flow when open (most swing check valves do) so you get maximum fill rates.

No don't use mushroom thru-hull, you won't be able to fill while on plane. Again, with the system above, it will not "force feed" the sacks or tanks.

I have a similar setup where I fill from the trhu hull and empty above the waterline and use a reversible pump. You need to use check valves to direct the water depending on which direction the pump is running. When filling, a check valve prevents the water from going out the drain fitting. While emptying, a second check valve prevents water from going out the thru hull used for filling. That way, I know when the sacs are empty and can shut down the Jabsco pumps.

Thx Bill what kind of check valves do you use? any pics of install?

A mushroom should allow you to fill while planing, my fishing boat has one for the livewell, 800gph pump, only sucks air occasionally. I guess it depends on how close you will be able to place it to the keel, but I know at 40-42 mph I'm still getting enough water to not lose prime and keep my bait alive.

I have pulled some seagrass into my whale checkvalve that made it stop functioning, but it was easy to clean since the two halves unscrew from each other. On a lake with not much aquatic vegetation, I would think this will not be a problem.

A flush thru-hull will absolutely allow you to fill while on plane, with either aerator or impeller pumps. If you're using impeller (reversible pumps) it doesn't matter which type of intake you're using. If you use aerator pumps you have to use a non-scoop style intake to prevent the bags from filling when at speed (with the pumps turned off).

I would be nervous about a mushroom through hull for high speed filling because I think it could create suction and contribute to burning out a pump early. My center console fishing boat uses mushroom through hulls to empty live wells and it sucks them dry if I pull the plug and take off.

There's also a little gravity coming into effect there. If you use a reversible pump then it would not matter what thru hull is used.

Ryan,

The check valves I used are from flexpvc.com They are the swing type and I used 1" valves and hose throughout the install. I do have some pics here...

http://www.wakeworld.com/MB/Discus/messages/65921/688346.html?1240197893

I changed from a manifold setup to 2 1" mushroom thru hulls, one for each pump. One pump fills/empties the front sacs and the other does the rears. Since both pumps are in the rear with the rear sacs, I just T'ed the line so that each pump empties out thru the vents for each rear sac.

Here is my plumbing diagram. I did add a check valve to each green drain line as well so the pumps wont suck any air from the vents while filling. System works perfectly.