Sharing thru-hull between watermaker and air conditioners.

[Tellie]

Originally Posted by sailjumanji

So Tellie (JT), if air is bad for the watermaker, am I causing damage when I clean out the strainer and restart the system with air in there. Ditto for after cleaning the 10 micron filter, as you can't get the air out of that canister either. I do notice it takes a while for the air to work thru and the stroke pressures to get up to normal. The manual doesn't cover this. Anyway, is there something special that needs to be done when restarting after strainer and filter clean, and introducing air into the system.

As Rich stated, consistent air ingress is the problem, bad O-rings, loose fittings, cracked hose etc.. Changing out filters and cleaning the raw water strainer will introduce air into the system but it is quickly purged before the system sees any pressure upon start up. If your system is an automated system it will send fresh water from your tank for 30 seconds upon start up purging the majority of air. If it is a manual system the feed pump/s won't make enough pressure on initial start up with air in the system to create any problems. It is normal for a Spectra to take a moment to reach pressure for this very reason and no, there is no concern for damage. You could always, on a manual system, open the pressure relief valve for about 20 seconds on initial start up and this will purge any air in short order as well. A little air pocket in the top of a pre-filter is also a normal occurrence and nothing to worry about. If your system has a real air ingress problem it will be evident in the brine discharge hose as a stream of air. No air present in the brine discharge hose, no air coming into the system.

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

[EvilRabbit]

Originally Posted by ErBrown

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.

Something to consider is do you really want to be crawling into tight spaces to be switching Y-Valves for the foreseeable future? Why limit the usage of your gear; why not run aircon and watermaker together? Or genset and aircon etc. Just seen that my Northern lights genset specifies that the inlet must not be from a forward facing scoop as this will damage the motor. As my aircon requires a forward facing scoop and genset shares that thru-hull on the opposite hull, we will be creating another dedicated line for that side too. Way less expensive than damaged gear.

[SV THIRD DAY]

Originally Posted by EvilRabbit

Something to consider is do you really want to be crawling into tight spaces to be switching Y-Valves for the foreseeable future?

Bingo...but here's how I've seen bad things happen.

You are making water in the anchorage, ever one is happy, drinks flowing and live is wounderfull when all of a sudden all hell breaks loose. The boat infront of you starts dragging and is heading right for you. In the panic you don't turn the water maker off and switch a Y-valve, you just start the engine and alert the crew to make ready to bouy the anchor and get the hell out of the way before your vessel takes a hit.

In the chaos you don't realize that for the last 20 minutes you have been running your main engine with no cooling water because you put a Y-valve on your main engine...it's over headed and in the chaos of yelling and screaming you failed to notice.

Ok...sound far fetched?
Well the exact thing happened to me TWICE while anchored in La Paz, except I didn't share a through hull and would NEVER share a through hull with my main engine or generator. Not because I don't want the head ache...but because I don't trust myself or others to remember to turn the Y-valve back to the device that will burn up without water cooling.

Sharing a wash down or head inlet with a Y-valve..sure...what can you really damage by having a faulty memory...but never would I recommend a water cooling device that can be damaged.

Because I've seen and have been part of these disasters...I preach against setting up the situation for one to happen.

[ErBrown]

Yeah I get it, a manual process before you can run either is definitely more error prone. I would never consider it for anything mission critical like the engine, fridge, etc. But remember this is AC and water maker. For us, it's very very unlikely we'll spend the $$$ to have enough generator to run our AC at anchor. So once we're cruising, the primary usage for the through hull would be the water maker. Once we're in a marina or somewhere with shore power, it's hard for me to imagine a scenario where we'd be running the water maker, so lifting a settee cushion and flipping a valve doesn't seem too tough.

Still, y'all make some good points and we will be hauling the boat for a bottom job before we head out, so adding a through hull is an option. Just not sure I like the idea of adding yet another hole in the boat for it.

Great examples here and thanks for sharing.

-EB

[jackonanthem]

We use one thru-hull for AC cooling, water maker and galley sink foot pump. No check valves or Y-valves. No dual use. Would however check that no air is pulled in on a new installation. 3 1/2 years.

[Sailmonkey]

Originally Posted by jackonanthem

We use one thru-hull for AC cooling, water maker and galley sink foot pump. No check valves or Y-valves. No dual use. Would however check that no air is pulled in on a new installation. 3 1/2 years.

Funny, that's our exact same configuration. To boot it's also a through hull I installed in the side of the keel as deep as I could get without worry of sucking sand in shallow water.


Sent from my iPhone using Cruisers Sailing Forum

[EvilRabbit]

While testing watermaker yesterday we started getting brine flow errors and system would shut down. Turns out there was air in the system and had to bleed it out. So yeah, air is a reality and risk to gear. Rather just do it right.