Sharing thru-hull between watermaker and air conditioners.

[EvilRabbit]

Builder has setup a single thru-hull for both my watermaker and air conditioning inlets. Looking over the installation manuals, both manufacturers specify dedicated thru-hulls that must not be shared. This requires a haul-out onto the hard. Any industry vets around that can verify y-valves or stopcocks are an adequate solve?

[ErBrown]

When we install our water maker, the plan is to share the thru hull with the AC. Since we'd never be running them at the same time, I don't see that as an issue.

Then again, since I have zero experience with actually doing it yet, it will be nice to hear from folks that do.

[Emerald Sea]

It should not be an issue providing one system is not starving the other where both systems are operating. Its a matter of having adequate flow to the pumps and thats a function of the inside diameter and any flow restrictions of your thru-hull and piping respectfully. If not sure, run them separately. One less thru-hull is always better.

[Dulcesuenos]

Check valves may be needed. What type of watermakers?

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[Cheechako]

a Y valve should be no problem. No different than each having it's own if you only run the one the valve is turned to.
Possible no Y required also. It depends on if one pulls too much leaving the other without full flow if both are in operation.... or if one pulls air into the system

[deblen]

Originally Posted by Cheechako

a Y valve should be no problem. No different than each having it's own if you only run the one the valve is turned to.
Possible no Y required also. It depends on if one pulls too much leaving the other without full flow if both are in operation.... or if one pulls air into the system

Suction by the operating system may apply some suction to the non-operating system & this may be a problem-not sure. Could use check valves,but they are a potential source of trouble also. / Len

[a64pilot]

Y valve that will only allow one to be connected, issue is with the watermaker, I believe air will significantly shorten the life of the membrane, with the AC off you could pull air through the line as air is less dense and of course a pump will pull whatever is easiest.
Why would you not run your AC and your watermaker at the same time?
I do not want yet another thru hull, but don't see any way around it. IP of course connected the heads to the engine strainer, I assume that works only because the heads have one way valves in them?


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[Tellie]

Shared thru hulls are not my favorite set up but can be done in some instances while not advised in others. A64pilot is correct, a watermaker can pull back feed water through the non running AC cooling system sucking air from the AC's discharge thru hull located above the water line. Once air is introduced expensive damage can be caused to most watermakers. If a thru hull must be shared, a three way valve, not a simple "T" is the best solution and each system run individually of the other. Size matters. A larger watermaker system is obviously going to demand more water and running both the AC and the watermaker at the same time will be trouble on the same thru hull. As boats keep getting larger every year more cruisers are demanding more comfort and AC is high on the list so it is not unusual these days to have boats running their AC and watermaker at the same time. But haul outs just to install a dedicated thru hull are expensive. New thru hulls can be done while the boat is still in the water a lot less expensive.

Halden Marine Services – Marine Watermakers, Solar Panels, Wind Generators

[EvilRabbit]

Originally Posted by Tellie

Shared thru hulls are not my favorite set up but can be done in some instances while not advised in others. A64pilot is correct, a watermaker can pull back feed water through the non running AC cooling system sucking air from the AC's discharge thru hull located above the water line. Once air is introduced expensive damage can be caused to most watermakers. If a thru hull must be shared, a three way valve, not a simple "T" is the best solution and each system run individually of the other. Size matters. A larger watermaker system is obviously going to demand more water and running both the AC and the watermaker at the same time will be trouble on the same thru hull. As boats keep getting larger every year more cruisers are demanding more comfort and AC is high on the list so it is not unusual these days to have boats running their AC and watermaker at the same time. But haul outs just to install a dedicated thru hull are expensive. New thru hulls can be done while the boat is still in the water a lot less expensive.

Halden Marine Services – Marine Watermakers, Solar Panels, Wind Generators

New thru hull can be done while still in the water? Might just be an option.

[EvilRabbit]

Originally Posted by Dulcesuenos

Check valves may be needed. What type of watermakers?

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It's s SeaRovery Aquamatic 900 watermaker.

[accomplice]

We have a sea recovery aquamatic 900 too! Ours shares it's through hull with 4 a/c units and perhaps a few other things. It is a big (2"? 1.75"?) thoughhull and seacock fitted to a large strainer/sea chest that feeds multiple raw water users. It generally works well, but if we've been in especially bouncy seas we need to bleed the sea chest before using the water maker or a/c units.

[SV THIRD DAY]

So far I have seen one over-heated generator, two burned out water cooled refrigeration systems, and one Hp water maker pump rebuild needed because of either a T or check valve placed in the water maker inlet pluming line.

Can you share a through hull...ya....but....you need to know the risks and do it right.

https://www.youtube.com/watch?v=XURN_awplww

[Hobie_ind]

There's enough variables here:
- size of thru-hull
- depth below waterline of thru-hulls and equipment
- head requirements of equipment
- flows
- line sizes, distances and pressure drops (filters, strainers, fittings) etc.
- ++++
that I doubt you're going to get a definitive answer without a more detailed analysis. Those variables are why almost every manufacturer will specify a separate thru-hull for their item....it reduces potential problems if somebody doesn't do enough engineering putting everything together.

Are you having problems with either system? If so, what? Have you asked the builder about it?

A number of builders do this. Our Amel has the engine, generator, 2 A/C's and the watermaker all of of one thru-hull via a manifold. Later models had the engine, generator, 3 A/C's, a much larger watermaker and both heads all supplied from the same manifold. No issues at all, but it was engineered well to start with. I looked a number of steel boats when we were shopping around that also did this with no apparent issues.

[ErBrown]

Originally Posted by a64pilot

Why would you not run your AC and your watermaker at the same time?
I do not want yet another thru hull, but don't see any way around it.
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Since we don't currently have plans for a generator, at least not one large enough to run our AC, we'd only be running it when on shore power. Water maker would only be run when well away from the funk of a marina. If we had a diesel genset that would probably change my perspective a bit.

I'd prefer to not add another thru hull but definitely don't want to be pulling air through our (eventual) spectra. I guess we could just go with a manual shutoff valve for either side of the Y valve? If making water, shut the AC side and vica versa?

As you can tell, haven't gotten to planning the water maker install yet. Hell, I still have no idea where I'll install the Cape Horn we'd like to buy. We'll get there eventually, but might be "out there" by the time we get to it.

[accomplice]

Do I understand you intend to have a watermaker but no genset to power it? Are you planning on a very large inverter?

If you're only planning on using the watermaker when on shore power, have you considered getting water from shore as well ?

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