AC drain idea

I bought this little venturi pump to try to hook up to my Ac drain. It currently drains into the center bilge area and the bilge pump can't get it all out. Stays wet all the time.

My plan was to put this pump inline on my AC raw water cooling line and hook the drain to the auction side. However, I noticed the restriction in the AC raw water line is pretty severe (see tiny hole in pump pic). Think that will cause too much back pressure on AC raw water line?

There is really no room to run the drain overboard due to the center location of the bilge area.

Dude!
I've bought one of these too to deal with that issue and had the same concerns... As I haven't installed it yet I don't know if that will be an issue. There are $200 units (Mermaid) out there that do the same thing and everyone seems happy with them. I'll update my experiences but it won't be until Spring.. Affordable $6 experiment if it doesn't work!

cardude01 said:

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Think that will cause too much back pressure on AC raw water line?

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Yes. It will never flow enought water with that small a restriction in the line.

Plus the hole look so small that it will clog up very easily.

Dammit! Maybe I could divert some flow to this venturi with a Y valve of some sort

cardude01 said:

Dammit! Maybe I could divert some flow to this venturi with a Y valve of some sort

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That's a thought worth pursuing...Let me know if you come up with a solution before i do!

Why don't you just open the hole up?

Capt.Bill11 said:

Why don't you just open the hole up?

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Thought about that but figured it was engineered to work with that small hole, and enlarging it might screw it up.

Opening up the hole would lose the venturi effect, but you don't really need the venturi effect on the suction side on the r/w pump.

I'm just wondering if this arrangement may cause you to lose raw water circulation due to sucking air in from the a/c drain line.

cardude01 said:

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I bought this little venturi pump to try to hook up to my Ac drain. It currently drains into the center bilge area and the bilge pump can't get it all out. Stays wet all the time............

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Well that's a really crappy design but you already know that. If you can get a similar device from an AC supply shop (particularly a marine one, it might work and not restrict the flow. Restricting the flow is not good)

Have you considered running the drain into a shower sump and then out through the hull? A shower sump has its own float switch and pump and is pretty well sealed so odor shouldn't be a problem.

You could even tie the output of the shower sump into a sink drain if you can't install a dedicated thru hull.

AusCan said:

Opening up the hole would lose the venturi effect, but you don't really need the venturi effect on the suction side on the r/w pump.

I'm just wondering if this arrangement may cause you to lose raw water circulation due to sucking air in from the a/c drain line.

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The device would be installed on the outlet side of the AC unit, not the inlet. If it sucks air (the pan is dry), it doesn't make a difference.

Right. The outlet side was my idea.

I still think the diverter valve idea might work, so I can control the water flow to this thing and let the excess pressure bypass to the thru hull exit.

AusCan said:

Opening up the hole would lose the venturi effect, but you don't really need the venturi effect on the suction side on the r/w pump.

I'm just wondering if this arrangement may cause you to lose raw water circulation due to sucking air in from the a/c drain line.

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I wonder how small the hole is in the Mermaid unit? Can't be that small or the A/C wouldn't work due to lack of water flow.

Got a shower drain sump? Both my AC's piddle into the shower sump. Works fine.

Why not put a condensate tank and pump near the A/C? It has a float valve and pump that runs only when it needs to and will pump it out wherever you want it. Many handle 10+ foot heads. The run from $50-80 each.

Stu

I can't run a hose from this centrally located bilge to anywhere. It's damn near impossible as far as I can tell. That's why I was trying to make this work and use an existing hose.

Sailboaters are making the venturi pump work.

http://forums.sailboatowners.com/index.php?threads/any-info-on-mermaid-condensator.119660/

They appear to be using a water bed drain kit. That fitting looks like it just tappers down a bit to create the venturi effect. As apposed to using a large restriction like that small hole.

If true, that would work just fine I would think. As far as maintaining proper cooling water flow goes.

WesK said:

The device would be installed on the outlet side of the AC unit, not the inlet. If it sucks air (the pan is dry), it doesn't make a difference.

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I probably didn't explain this very well.
Its the engine sucking air that I would be concerned about.

An off the shelf diaphram pump will do almost as well as a shop vac.

But unless there is a pit to drain YOU will have to operate the of/on switch .

As these pumps can run dry , I would use a timer , and just let it run for 10-15min.

Most wet switches don't do well with 1/4 inch of water.

Capt.Bill11 said:

They appear to be using a water bed drain kit. That fitting looks like it just tappers down a bit to create the venturi effect. As apposed to using a large restriction like that small hole.



If true, that would work just fine I would think. As far as maintaining proper cooling water flow goes.

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The venturi I have has a one way valve that won't let the pressurized water inadvertently flow back into the suction side. I don't think the water bed fill has that. Or maybe that's not a concern?

But I agree, if the hole on my unit is too small it could restrict water flow so much that it will cause other problems. Also, if any gunk from the AC pan gets into this little valve it's gonna clog it up. Hmmmmm.

Waterbed drain cutaway (I think). This is not the actual plastic waterbed drain but I think this is how it works.


This actually looks like a better solution IMO.
I think I will order one of the $6 waterbed drains also and compare.

I do worry if either one of these plastic venturi based pumps will hold up to the pressure of the AC raw water pump. Does anyone know what the PSI is on these systems?

cardude01 said:

There is really no room to run the drain overboard due to the center location of the bilge area.

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FWIW, one of our AC condensate drains is plumbed to the shower sump...

-Chris

ranger42c said:

FWIW, one of our AC condensate drains is plumbed to the shower sump...

-Chris

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I can't find a way to run a hose from the AC unit (or the central bilge) location to the shower sump.

If the drain can be installed above the water line it should be fine.

Capt.Bill11 said:

If the drain can be installed above the water line it should be fine.

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Yeah where I would mount it would definitely be above the waterline.

And when the AC pump is off I think it shuts off possible water flow from the thru hull, but I could be wrong on that.

If shower sump is below ac unit elevation-wise, a hose can be run. Just want a gradual downward slope the whole run or it will get a loop trap and won't drain.

cardude01 said:

I can't find a way to run a hose from the AC unit (or the central bilge) location to the shower sump.

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I was thinking of an additional, dedicated shower sump for the AC condensate. And of course if the condensate pan is above the waterline, just install another thu hull and let gravity do it's thing. That's how mine is set up.

cardude01 said:

I can't find a way to run a hose from the AC unit (or the central bilge) location to the shower sump.

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And not everyone has an automatic sump drain. Mine is switched on manually...

I'm thinking the "Y" valve mentioned earlier is a good solution. Divert enough through the venturi to drain the condensate without significantly reducing overall flow through the system. Simple to do also..Just run in parallel to your existing cooling line.

Heron said:

And not everyone has an automatic sump drain. Mine is switched on manually...

I'm thinking the "Y" valve mentioned earlier is a good solution. Divert enough through the venturi to drain the condensate without significantly reducing overall flow through the system. Simple to do also..Just run in parallel to your existing cooling line.

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I cant imagine why all sumps arent auto. My boat has (amateur built) sumps from 20 years ago and they have level switches in them. The breaker in the distribution panel supplies the power and the level switch controls the sump.

what_barnacles said:

I cant imagine why all sumps arent auto. My boat has (amateur built) sumps from 20 years ago and they have level switches in them. The breaker in the distribution panel supplies the power and the level switch controls the sump.

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My boat has no actual shower sump. It has a pump that's capable of running dry so you just step into the shower and turn it on and off as necessary. Hair and soap scum can cause automatic pumps to jam.

And while we're on the subject of AC condensate, a slip neighbor of mine complained that whenever he ran his AC, he got water in the cabin.

Long story short, the AC condensate line ran half the distance of the boat into a sump with an automatic pump but for some reason the sump itself had a built in restriction in the inlet and rust and dirt had clogged the hose where it entered the pump. Simply pulling the hose off the sump cleared the hose and it started working again.

My boat does the same thing with the water draining into the bilge where it collects in the keel. The keel has a forward and aft pump mounted, they are small Rule manual pumps that fit the narrow width of the keel. I've considered all of these fixes but all have drawbacks, the plumbing to a centrally place shower drain box seems to be the problem with this, there is not much drop from the forward unit to the bilge. The Venturi method requires regular maintenance to keep it Fromm plugging up. IMHO the most trouble free method is the remote mounted diaphram pump using a suction foot that'll leave only a 1/16" or less water in the keel. I have bought bought a Mermaid Venturi type and a shower pump box with a float switch and Rule pump and after more thought decided against going each route. When the current manual stripper pumps fail I will replace them with Whale diaphram pumps which I've also bought, I have yet to buy the proper foot for the suction hose but will find or fabricate something that will keep the bilge drier than it is currently.


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