Water System Problems

[Dockhead]

OK, thanks. I'm still a bit torn on which way to go with this, and it irritates me that I'm spending so much time on what should be a trivial problem when I have such a long list of other boat jobs.

The two approaches, summary:

1. Make a bet on a new Marco pump. Switching is electronic so should solve the pressure switch issue. Installation very clean, eliminating accumulator tank, no external switch, no significant plumbing work.

2. Self-engineer an external pressure switch using in industrial pressure switch. What is elegant about this is that an industrial pressure switch with a relay (I'd probably go solid state for reliability, cleanness of switching, at the cost of voltage drop) should be bomb-proof (i.e. massive overkill of the problem at hand). Set points and hysteresis adjustable. The switches are rated for either a million or 10 million cycles. And will work with any old standard marine pressure pump, including the ones I have on board. Plumbing work is not that daunting. Less risk than with the Marco pump, which I am only assuming is reliable. Fixing it, if it breaks, will not require any proprietary parts. Downside -- I'll spend more hours choosing one and ordering it plus relay etc., then more hours redoing the plumbing and wiring, vs. just popping in the new Marco pump.

Both seem to be quite good solutions. Die Qual der Wahl. Hmmm.

[nofacey]

Time is precious - get a new variable speed pump that operates in the pressure range you desire (they are not all the same), spare the pressure switch, and decide weither you want to keep existing as a rebuilt spare, or buy two of the new.
- having an accumulator is a good idea.

Yea, it’s an old classic approach - classic because it works. Go sailing!

[becrux]

I was looking for Jedi to chime in as I have recently seen something on this topic (on his FB page?) You are all familiar with his “never fail” approach.
I believe he has two pumps always online - one for each tank. Switching tanks is a matter of throwing breakers, which is very handy if you’re in the middle of a shower.

There is also a relatively simple crossover valve system. Yes, there is a little more plumbing involved to set it up but the versatility is excellent, especially when a switch or diaphragm fails. How complex you want to make it is up to you. But you will never be without water unless both tanks are dry.

For higher flow one can use both pumps to draw from both tanks simultaneously.

OK, I found his graphic. Thanks, Jedi. (Credits are on the graphic, so I don’t feel guilty about posting here)

[wrwakefield]

This ^^ is a good approach to help mitigate cruising interruptus.

Perhaps I should have elaborated further in my initial post (#10):

I have 2 variable speed [potable water pumps] plumbed in parallel [as hot back-up to each other - not simultaneous use; no pressure tank needed] and I switch between them every year [to wear them evenly since they last so long they will be (are now) obsolete when they start to fail…]

It only takes 2, 3-way valves [1 each water in/out] and one single pole 3-position switch [fed by existing water pump breaker] with center off position [near the pumps for convenience during infrequent maintenance.]

I do this because cruising [living] time gets priority…

FWIW

Cheers, Bill

[becrux]

I see. Eliminating the pressure tank by using variable speed pumps also gives you more room for the second pump.

[Dockhead]

Originally Posted by becrux

I was looking for Jedi to chime in as I have recently seen something on this topic (on his FB page?) You are all familiar with his “never fail” approach.
I believe he has two pumps always online - one for each tank. Switching tanks is a matter of throwing breakers, which is very handy if you’re in the middle of a shower.

There is also a relatively simple crossover valve system. Yes, there is a little more plumbing involved to set it up but the versatility is excellent, especially when a switch or diaphragm fails. How complex you want to make it is up to you. But you will never be without water unless both tanks are dry.

For higher flow one can use both pumps to draw from both tanks simultaneously.

OK, I found his graphic. Thanks, Jedi. (Credits are on the graphic, so I don’t feel guilty about posting here)

I see Nick is using the Marco pumps. I'll take that as a vote of confidence, one I give a lot of weight to.

Of course redundant pumps is a great way to mitigate the risk, but that's that much more complexity and weight in the boat. Well, I guess it's not more weight than carrying a spare.

I wish these were reliable enough that we didn't have to think this way.


I have two 500 liter water tanks, so could duplicate Nick's system. But it would be a lot of replumbing; I don't think it's worth it for my case. To do it right I'd need a second level gauge, too. I don't want to make such a big project out of this; I have a long enough list of other stuff to do.

[Dockhead]

Originally Posted by wrwakefield

This ^^ is a good approach to help mitigate cruising interruptus.

Perhaps I should have elaborated further in my initial post (#10):

It only takes 2, 3-way valves [1 each water in/out] and one single pole 3-position switch [fed by existing water pump breaker] with center off position [near the pumps for convenience during infrequent maintenance.]

I do this because cruising [living] time gets priority…

FWIW

Cheers, Bill

If it's reasonably reliable, though, it's almost as good having the spare on board, isn't it? I could swap mine in 10 minutes I think.

[Dockhead]

Originally Posted by nofacey

Time is precious - get a new variable speed pump that operates in the pressure range you desire (they are not all the same), spare the pressure switch, and decide weither you want to keep existing as a rebuilt spare, or buy two of the new.
- having an accumulator is a good idea.

Yea, it’s an old classic approach - classic because it works. Go sailing!

I'm still finding this decision hard to make.

The Marco pump seems like a good solution. I GUESS the pressure switch should be much, much more reliable since it doesn't switch high power. By the looks of it, it is some kind of industrial sensor and not some crap microswitch like the others use.

Buy two of them (€600) and job done. Throw the whole box of old pumps and switches into the trash. If I could be sure, rather than just guessing, that the Marco pump is as reliable and long-lived as my old original Shurflo was, I'd definitely go this way.

Could well be the right way to do it.

On the other hand -- installing a separate, industrial-quality switch plus solid state relay, improves the architecture of the system substantially. Separate switch problems from pump problems, and a really good industrial switch with advertised MTBF of millions of cycles, is probably completely bulletproof. Use any pump. Keep spares of everything.

Well, I need to decide soon. I want to order this kit and get it installed the next time I'm on board, put this problem to bed, so I can get started on my list for this year.

[Frank60]

I'm looking for a spare pump and had not heard of Marco until seeing this thread. Looking at the manual for the pumps, I came across the following. Seems like a hassle. It doesn't say why you should do this:

"If it is expected that the pump will not be used for a period of at least 30 days, especially in the case of usage with water, it is advisable to run fresh water through it and to then loosen the front plate screws. Upon re-use, run the pump briefly (a few seconds) and tighten the screws again. Check under conditions of maximum operating pressure that the motor current value is within the motor label specifications."

[Loredo]

Several years ago, I've tried the external pressure sensor route. With the pressure sensors I could get my hands on back then, the hysteresis wasn't ever right. Having a shower was a pain. Not enough flow or full bore, repeat, there was no "right" setting I could find. I messed with this for over a year and then went back to the "normal" on/off pump.



On the other hand, I've helped a buddy installing a Marco pump several years ago. Back then those variable speed pumps were a novelty. That pump is still in use and never had the even slightest glitch. Anyhow, even with those pumps you should still have a pressure tank. The reason is the water heater. When the water is being heated it expands and the volume needs some place to go... Today, when my pump will need repalcement, I have no doubt, I'll go with a Marco pump.

[Dockhead]

Originally Posted by Loredo

Several years ago, I've tried the external pressure sensor route. With the pressure sensors I could get my hands on back then, the hysteresis wasn't ever right. Having a shower was a pain. Not enough flow or full bore, repeat, there was no "right" setting I could find. I messed with this for over a year and then went back to the "normal" on/off pump.

On the other hand, I've helped a buddy installing a Marco pump several years ago. Back then those variable speed pumps were a novelty. That pump is still in use and never had the even slightest glitch. Anyhow, even with those pumps you should still have a pressure tank. The reason is the water heater. When the water is being heated it expands and the volume needs some place to go... Today, when my pump will need repalcement, I have no doubt, I'll go with a Marco pump.

Another testimony for Marco. Thanks.


Concerning hysteresis -- yeah, you absolutely need a switch with adjustable set points. Those are readily available. They are not cheap, especially if you add the cost of a solid state relay, but not as expensive as a Marco pump.

[Lindsaymcm]

Originally Posted by Dockhead

… Russian airspace is closed, getting to and from Northern Europe to SE Asia has become much harder, longer, and more expensive. Singapore used to be a reasonable nonstop flight from Helsinki or Copenhagen; now it's a rather grueling trip with a stop in Doha, Dubais, or Istanbul, and overnight in both directions ...

Can’t help with the water problem sorry, as I’m a complete and utter technical numpty. But I few Singapore to Copenhagen recently with Singapore Airlines. Direct flights, routed south of the Black Sea, virtually the same flight time as previously over Russia.

Curious to know why you didn’t fly with them.

[Dockhead]

Originally Posted by Lindsaymcm

Can’t help with the water problem sorry, as I’m a complete and utter technical numpty. But I few Singapore to Copenhagen recently with Singapore Airlines. Direct flights, routed south of the Black Sea, virtually the same flight time as previously over Russia.

Curious to know why you didn’t fly with them.

I saw that flight, but didn't take it because:

1. The cost was 4x for that particular day; and

2. Same number of hours in the air (almost 14 hours!!), same terrible overnight timing, but without a break.

The new Istanbul airport has showers and is a decent place to drink tea and gird yourself for the next leg.

14 hours in tourist class without a break is just too much for me at my age. And overnight to boot! Bleh! That's almost 3 hours longer than it was before the war.

I've agreed with my partners that after the very first funding round, the travel policy is revised!

[Bowdrie]

Originally Posted by Dockhead

yeah, you absolutely need a switch with adjustable set points. Those are readily available. They are not cheap, especially if you add the cost of a solid state relay, but not as expensive as a Marco pump.

They're actually quite inexpensive, even Ace Hardware is not far off from this price.
No, you don't need a relay, they directly control the pump.
My original Furnas switch lasted 25 years, and can be rebuilt as new with a $20 kit.
The Square D that's now in use should last 10>15, and replacement contact kit is only ~$15.
https://www.ebay.com/itm/38661750829...Bk9SR8CsgfavYw

[s/v Jedi]

Originally Posted by becrux

I was looking for Jedi to chime in as I have recently seen something on this topic (on his FB page?) You are all familiar with his “never fail” approach.
I believe he has two pumps always online - one for each tank. Switching tanks is a matter of throwing breakers, which is very handy if you’re in the middle of a shower.

There is also a relatively simple crossover valve system. Yes, there is a little more plumbing involved to set it up but the versatility is excellent, especially when a switch or diaphragm fails. How complex you want to make it is up to you. But you will never be without water unless both tanks are dry.

For higher flow one can use both pumps to draw from both tanks simultaneously.

OK, I found his graphic. Thanks, Jedi. (Credits are on the graphic, so I don’t feel guilty about posting here)

Good to see my new design finds its way here I have stopped posting my designs on the forum because of all the attacks etc. but have no problem at all with people posting them

I have since added a very small 0.75 liter accumulator tank to the design.

With two Marco pumps you can opt for pumps that are on the smaller side. If you ever need more capacity than the pump can deliver, you simply run both.

I am particularly happy with the filters and the rectangular bucket. Anyone maintaining filters understands why. For the carbon block filter I use the NSF rated one from Pentek as discussed on the forum many times.
The filter housings have a (red) bleeding knob on top and are also Pentek housings.

I am currently testing this setup with old pumps of which one doesn’t want to prime and the tank/pump manifold works as expected.