Water System Problems

[Dockhead]

Originally Posted by s/v Jedi

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.

Great you weighed in, Nick.


What's your opinion about the Marcos pumps? How long have you been using them?


I think the 15l/m one would be ok for me. I was using a 12l/m one and it was low flow when multiple outlets were being used but acceptable. The low flow was even an advantage for water consumption. I could, for example, take a shower while the washing machine was running with no problem, or two people showering at the same time. So 15l/m will be ok.


Why did you decide to add the accumulator tank?

[Dockhead]

Originally Posted by Bowdrie

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

Using a well pump switch like this is another approach to the problem.


Less precise and probably not nearly as long lived as an industrial pressure switch but cheap and heavily built and probably very reliable.


Cheap and compact enough that carrying a spare is no problem.


I like it.

[s/v Jedi]

Originally Posted by Dockhead

Great you weighed in, Nick.

What's your opinion about the Marcos pumps? How long have you been using them?

I think the 15l/m one would be ok for me. I was using a 12l/m one and it was low flow when multiple outlets were being used but acceptable. The low flow was even an advantage for water consumption. I could, for example, take a shower while the washing machine was running with no problem, or two people showering at the same time. So 15l/m will be ok.

Why did you decide to add the accumulator tank?

I have the UP3/E new in box, soon to be installed to replace a failed AquaJet pump. So no direct experience yet but think they are one of the better options.

The variable rpm pumps are different. A 15l/m pump can also be a 10l/m pump when that’s all the demand there is. Instead of cycling, it will reduce rpm by 1/3.

I add the small accumulator tank for a smoother water flow, smoother running of the system. I may remove it when I see no difference.

[Dockhead]

Originally Posted by s/v Jedi

I have the UP3/E new in box, soon to be installed to replace a failed AquaJet pump. So no direct experience yet but think they are one of the better options.

The variable rpm pumps are different. A 15l/m pump can also be a 10l/m pump when that’s all the demand there is. Instead of cycling, it will reduce rpm by 1/3.

I add the small accumulator tank for a smoother water flow, smoother running of the system. I may remove it when I see no difference.

Thanks!

[stormalong]

Originally Posted by Dockhead

I hadn't thought of a relay. That's a great idea.

A relay is the easiest solution to the micro switch problem. Micro switches just can't handle the starting current for a pump motor. Every time the pump starts that micro switch burns the contacts a little until is finally fails. By offloading that current spike to a relay the micro switch will last forever.

I use automotive headlight relays on all of my pumps. They are cheap and available at any auto parts store. Sockets are available too. So when they eventually fail they are easy to replace. By using the same relay in all pumps you do not need to carry as many unique spares. I think I have only needed to replace one or two in the last decade.

Save the cost of new pumps and a lot of re-work. Just fit relays.

[Dockhead]

Originally Posted by stormalong

A relay is the easiest solution to the micro switch problem. Micro switches just can't handle the starting current for a pump motor. Every time the pump starts that micro switch burns the contacts a little until is finally fails. By offloading that current spike to a relay the micro switch will last forever.

I use automotive headlight relays on all of my pumps. They are cheap and available at any auto parts store. Sockets are available too. So when they eventually fail they are easy to replace. By using the same relay in all pumps you do not need to carry as many unique spares. I think I have only needed to replace one or two in the last decade.

Save the cost of new pumps and a lot of re-work. Just fit relays.

Is a flyback diode needed with a mechanical relay, or just with a solid state one?


I'm thinking if I use a well pump pressure switch I won't need a relay, but if I go with an industrial pressure switch, I surely will.


I am not going to replace the standard tiny non-adjustable pressure switches. Once I'm this deep in it, I might as well make it separate, which is better architecture and better kit.

[stormalong]

Originally Posted by Dockhead

Is a flyback diode needed with a mechanical relay, or just with a solid state one?

I'm thinking if I use a well pump pressure switch I won't need a relay, but if I go with an industrial pressure switch, I surely will.

I am not going to replace the standard tiny non-adjustable pressure switches. Once I'm this deep in it, I might as well make it separate, which is better architecture and better kit.

I have been using these automotive 40 amp relays without any flyback diode or de-spiking circuits for a long time. No problems.

The one exception is the windlass contactor - big relay driven by little relay where I am using de-spiking circuits. Actually three relays. The little relays on my cordless control did burn up driving the contactor directly so I added another level. No problems since - about fifteen years now.

[s/v Jedi]

I think many automotive relays already have a diode internally?

[stormalong]

Originally Posted by s/v Jedi

I think many automotive relays already have a diode internally?

I don't think so. If that were the case polarity would have to be indicated on the relay coil connections which they aren't.

[rslifkin]

Some relays have an internal diode and are polarity sensitive on the coil, some don't have a diode. You'd have to check for the specific relay you're planning to use.

[s/v Jedi]

Originally Posted by stormalong

I don't think so. If that were the case polarity would have to be indicated on the relay coil connections which they aren't.

Which is why they show the diode in the diagram printed on them.

[Dockhead]

In case anyone is interested in how I came out on this:

After some thought, I decided that with so many other jobs on board, it would not be right to make too big a deal out of this. To overthink it, to spend too much time and money on it, to over-engineer it.

I found the microswitch on Mouser, the one which failed on my Johnson pump, a Honeywell job which costs €6. I bought two of them.

I bought an entire new pressure switch for my Par Max 4 for €40.

So now I'll have two relatively new and perfectly good pumps.

I bought a solid state 40 amp relay plus a spare. I have a box of diodes on board to use as a flyback diode, and I have some nice junction boxes to mount the relay in.

Should be an hour job to replace the pressure switch and install a relay, maximum two, job done, then I can get on with the rest of my list. Cost -- less than €100 (if €1000 is a "boat buck", is €100 a "boat dime"?).

I recognize that the external pressure switch is better, but it would require some replumbing and moving the pump to mount it -- an easy job, but nevertheless, a couple extra hours of work plus need to find and buy fittings, so probably a trip or two to another town to the plumbing supply shop, a couple of hours round trip. I decided that since I have been perfectly happy with the non-adjustable pressure settings on the standard pressure switches that this will be a perfectly good solution with a relay to extend the life, plus spares on board.

This is my KISS approach to solving this problem.

[Dockhead]

Question for you EE geniuses on the forum:

Water pump is an inductive load, like all electric motors, right?

So does this circuit need a snubber circuit too (across the load terminals), besides a flyback diode (across the coil terminals)?

[s/v Jedi]

Originally Posted by Dockhead

Question for you EE geniuses on the forum:

Water pump is an inductive load, like all electric motors, right?

So does this circuit need a snubber circuit too (across the load terminals), besides a flyback diode (across the coil terminals)?

Attachment 286167

Hold on, hide that picture… we’re talking DC here…

[Dockhead]

Originally Posted by s/v Jedi

Hold on, hide that picture… we’re talking DC here…

Oops.