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Chotu · 12-10-2020, 17:03

I guess the issue is Tellie said this wouldn’t work well.

But it’s working for you, so maybe it’s just pushing the pumps near their limit.

You’re right here. Just try it. If it doesn’t work or breaks a feed pump prematurely, I’ll adjust it later.

Thanks

Quote:

Originally Posted by waterman46

Again, you don't need a lift pump. The feed pump is easily capable of priming. Why don't you simply try it before wasting time figuring out how to provide water using another pump? Having to use a second pump just will cut the efficiency terribly. And if you do that, you'd have to have a reservoir to receive the output of the additional pump, with an overflow tube near the top, not just a Y valve. At bottom of reservoir would be your outlet to the input of the feed pumps.

Yes, do dump the output of the feed water down low. In theory it will improve the flow rate. You'd probably want to dump it low anyway.

If you have feedpumps with higher volume capacity, those won't damage the Clark pump. Set the pressure switch on your feed pump max pressure, with feedpump output totally blocked, to 120 psi. That protects the Clark pump in case it gets stalled.

The Clark pump part that receives the feed pump flow is basically a couple of cylinders with valves controlling when the water flows into and out of them. The valves control the cycling of the piston that drives high pressure water into the membrane housing. Those valves will switch to the next cycle whenever the cylinder reaches end of travel. Higher feed pump water flow will just make that happen sooner.

I have been using my Spectra 380C since 1997. It works great, but the Clark pump has needed a rebuild twice due to cracks in the housing. I guess that's not to bad, 10 years between service. Replaced the feed pumps once also. In my installation they have to suck water 20 feet from the forward part of the boat, then up 3' to the feed pumps in the engine room. They prime very quickly, even after I have drained the 20' feed line to keep it free of marine growth during long storage.

Idylles15.5 · 12-10-2020, 17:34

Anyone have a Tecnortham watermaker? Just looking at 150 gal day for 3600 on ebay, but i dont know anything about them. Any good? Anyone on here have one?

john manning · 12-10-2020, 18:02

I assume you are talking of a temporary suction hose dropped into the water only when you are making water. If so, and you are worried about lift, put a bilge pump on the end of the hose.

My Spectra water maker is very sensitive to flow. ie Not enough flow across the filter then water comes out salty. The Spectra feed pump is the main control point for this. It needs both flow and pressure to do a good job.

Jon Hacking · 12-10-2020, 18:37

Quote:

Originally Posted by Chotu

It’s a completely custom, 50’ ultra light, high performance, cruising cat. It’s epoxy infused core cell/glass. It has plenty of design philosophies that are adhered to in order to solve marine problems in better ways and to simplify things.

No through hulls below the waterline is one of them.

Water would typically be made at anchor or in very calm conditions.

Chotu, how about this: Create an EXTERNAL water line coming up the side of the hull & entering wherever you think it's safe? This would keep the intake underwater at all speeds.

You really want to run your watermaker every few days, so long passages would be a problem if you could only run it at anchor. You could pickle it for long passages, but the Spectra pickling compounds cost about $10 (& you can't use sodium metabisulfide like everyone else).

If you want to be really slick, you could keep it flush on the outside & compensate on the inside.

Also, the heat-sink around the motor is just held on by its spring force, so it's easy to take off. Then you can peel the Spectra sticker off to see what pump they bought. It's usually a ShurFlo of some sort. Then you could look up the specs for that pump.

On a related note, one thing Spectra won't tell you is that those pumps wear out. We usually get about 700 hours (~2-3 years) out of a pump head, especially if you run both pumps together, which increases pressure & wear (& water quality). Instead of getting new ones from Spectra, Googling the ShurFlo number will usually result in an exploded parts diagram, with part numbers. Googling those part numbers will reveal a number of (non-marine) places to buy. You can buy the pump head complete, or just the diaphragm, which is the part that usually wears out. Last time we looked, the complete heads were about $150 & the diaphragms were about $40.