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Remote two way valve for flushing the water maker
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I found this two way valve to make it possible to flush the water maker without going down to the engine room. A bit expensive 450 €. anyone know a cheaper solution. Yrs I know open the hatch and go down the engine room is a cheaper solution but I'm looking for a remote controlled way to flush the water-maker
Paul SY Kerpa SM#259 Lagos 
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David Wallace
Paul, I bought two ss 12v solenoid water valves on eBay, one normally open, one normally closed. If I remember correctly they were about $50 each. Unpowered feeds saltwater to the RO, powered feeds freshwater from the tank. Ran wires to the companionway area
with a single switch. The switch is wired through the RO on/off power switch so the solenoids can’t be switched unless the system is running. It’s worked well for 9 years now.
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Dave Wallace
s/v Air Ops
Maramu #104
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Hi Paul,
I bought two 24V DC Solenoid valves on Ebay, one NO the other NC. The NO valve is in the saltwater feed line and the NC Valve replaces the manual flush valve and feeds fresh water through a TEE into the filter housing. The bottom of the 3 connectors on the TEE has the NO solenoid for saltwater supply connected to it. The solenoid valves are wired to a small 24VDC digital timer, also from Ebay which is ,mounted in the cupboard space above the sink. The timer has 3 functions OFF, MANUAL, AUTO. When away from the boat, we ensure the water tank is full and the timer is set to Auto to flush for two minutes at 1000 Mon, Wed, Friday. It only uses about 4-5 litres each flush. The whole set up probably cost less than $100. Cheers Alan Elyse SM437 |
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Oh and I should have said the 24VDC timer also sends 24VDC to a relay which switches power to the FW pump so you don;t need to leave the boat with FW pump switch on. The relay and a circuit breaker for the pump supply are mounted in the circuit breaker box for the watermaker etc on the engine room forward wall.
Cheers Alan Elyse SM437 |
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On Thu, Oct 24, 2019 at 07:03 PM, Alan Leslie wrote:
Dave and Alan thanks, great idea with the timer, as I often forget to flush my membranes. If I understand it right on the saltwater side you have a "remote" valve open when no current and on the fresh water side the valve is open when current is on so when the current is on it flush with freshwater, as the saltwater valve is closed, and when current off it is free passage of salt water if one want to operate the desalinator.Paul on SM#259 SY Kerpa |
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David Wallace
Paul, yes that’s how it works. With no power on the solenoids the open one let’s salt water in and the closed one keeps freshwater out. Throwing the switch provides power to both solenoids simultaneously which closes the saltwater solenoid and opens the fresh
water one. When done flushing I then turn off the RO master switch and power is simultaneously removed from both solenoids (since power to them is routed from the “downstream” side of the master power switch) so they return to their normal state: if I just
turned off the solenoid switch saltwater would be introduced again until the RO system was shut off. Then be sure to turn off the solenoid switch or else you'll be making water with your own freshwater when you next start up your system! I've just built a
relay switch to solve that problem but haven’t installed it yet.
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Good luck!
Dave Wallace
s/v Air Ops
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Yes Paul, that's how it works.
And when we start the watermaker we run it for a few minutes to allow the incoming saltwater to fully flush out the fresh before increasing the pressure slowly to start making water. Fresh water applied under pressure to the membranes will damage them. Cheers Alan Elyse SM437 |
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Hi Alan, I'm glad that you mentioned wiring in the fresh water pump. I have the flush solinoid, but have not controlled the fw pump that way. That has left me with the concern of leaving the pump on and FW system pressurized while away. Can you provide any more detail on how that is wired in relation to the normal FW pump breaker? And is there any risk of interference when the FW pump is operating normally. I still operate the T valve to switch between the sea water inlet and the FW loop manually. Thanks and regards, Daniel Carlson on sv BeBe, SM#387. On Thu, Oct 24, 2019, 8:05 PM Alan Leslie <s.v.elyse@... wrote: Oh and I should have said the 24VDC timer also sends 24VDC to a relay which switches power to the FW pump so you don;t need to leave the boat with FW pump switch on. The relay and a circuit breaker for the pump supply are mounted in the circuit breaker box for the watermaker etc on the engine room forward wall. |
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Hi Dan,
I took a 24V positive feed from the 24V supply that's on the forward wall of the engine room to a circuit breaker mounted in the same box as the watermaker cct breaker. From the cct breaker to a relay which is controlled by the timer. From the other side of the relay to the positive feed to the FW pump in parallele with the positive feed from the galley cct breaker for the FW pump. I switch off the galley cct breaker when leaving the boat and set the timer to Auto. No, there is no interference with the normal operation of the FW pump. Cheers Alan Elyse SM437 |
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