Noise issue with RODI reservoir float valve kit

[Tastee]

Hi all, I have just setup a new RODI reservoir and are having a noise issue, which I think is coming from the pressure sensitive solenoid. I was wondering if anyone has any experience with these devices and could suggest a solution. Details are below. I’ve also emailed Aquatic Life so will see what they suggest.

The RODI reservoir is in an outside housed cabinet using an 4 stage twist-in Aquatic Life RODI unit, plumbed to an 80 litre reservoir controlled by the Aquatic Life Float Valve kit. It is working well but I am having a noise issue as the reservoir fills up and the solenoid cuts the inlet water supply.

In the final stages of filling the reservoir there is a significant humming/thrumming noise that is generated. This lasts for 15 mins or more. In my setup as I have the reservoir connected to a Neptune APEX ATO kit to top up my aquarium inside the house, so there is a small water usage every couple of hours, and immediately after that I have the noise issue.

When this happens the water inlet line is vibrating substantially, as is the solenoid. The solenoid is pinned to the timber backing and I have already tried loosening the strap holding it in place and putting some padding behind it, which didn’t help. Securing the inlet line also doesn’t really achieve much, as it seems not to be the cause of the vibration, rather just one of the symptoms.

I have included two photos of my setup. The water inlet line is the one on the top left, and it goes outside the cabinet and straight down on the left to the tap using a Buddie fit connector.




The water inlet is coming from our mains supply. I checked with my plumber and the tap being used (dedicated for this) is a quarter-turn ceramic disk tap, so there is no chance this is causing any water hammer. This seems to only leave the solenoid as the culprit, and as it is pressure sensitive, I assume it is spring loaded inside.

Our water mains should be around 500 KPA or ~50 PSI. It is possible my supply is a little higher pressure, and I have not measured it at this point. This seems well within the 40-80 PSI rating however.

One possibility is that this is an inlet water pressure issue and I need to fit a pressure limiting valve. In this case I’m not sure what inlet pressure I should shoot for - possibly the low end of their range ~40 PSI?
I don’t mind if this slows down water production as my usage is fairly low.

Appreciate any suggestions, Brad.


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[fishyguy7]

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[mcgyvr]

Whats inlet pressure?
Try turning the ASOV valve so the 2 tubes on each side are vertical and not horizontal..
The diaphragm is fluttering as the float starts to close off..

While annoying its really not causing a problem besides that..

[Tastee]

Thanks mcgyvr,

I’m not sure what the inlet pressure is, but there is a good chance it is at least a little too high. I have noted the noise is worst overnight and water demand then would be lowest meaning my inlet pressure would be higher. That supports an inlet pressure issue. A pressure limiting valve certainly sounds like a good first step. I’m thinking of starting with around 50 PSI.

I didn’t think of changing the orientation of the solenoid, so will also try that after fitting the PLV (one change at a time). Which sided you think should be on top, inlet or outlet?
I would think inlet.

Thanks, Brad,


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[mcgyvr]

Kit is rated 40PSI min/80PSI max..
I have no idea about plumbing down under but in the US most have a pressure regulator valve on the homes supply line typically set for 35-60PSI or so.. (adjustable obviously)

As to orientation.. Last I remembered side with the screw heads is "bottom"
Embossed text side is "top"..

[Vinny Kreyling]

Tastee,
Intermittent running of the RO unit is NOT recommended.
This causes the membrane to clog because the unit does not run long enough to flush contaminates.
Better to shut the unit off & refill container when low.
Bit of a pain I know but better off.
The real problem is the float valve does not shut off quickly enough, causing pressure surges in the line.

[mcgyvr]

Originally Posted by Vinny Kreyling

Tastee,
Intermittent running of the RO unit is NOT recommended.

I'd use the words "short cycling" vs intermittent..
(sorry.. just me being picky)
But yes..I have ONLY used a mechanical float like that as a "oops..forgot to turn off the RO water" and not as an on/off switch as like you said short cycling is not recommended with RO/DI systems..

Some water filter companies though are happy to sell you a setup like that is all you do is buy filters faster

[Vinny Kreyling]

Being Correct is not IMHO being "picky".
Look @ the bottom line ----

[Tastee]

Originally Posted by Vinny Kreyling

Tastee,
Intermittent running of the RO unit is NOT recommended.
This causes the membrane to clog because the unit does not run long enough to flush contaminates.
Better to shut the unit off & refill container when low.
Bit of a pain I know but better off.
The real problem is the float valve does not shut off quickly enough, causing pressure surges in the line.

Thanks Vinny, Aquatic Life also gave me similar feedback. I am planning to change the ATK programming in the APEX to only draw water once a day at midday, which will reduce the TDS creep issue as the RODI top up should then only be activiated then, or if I draw water for a water change.

As you suggest I can always just manually turn the tap off during the week as well and just run it on weekends, as you are correct, the 80 Litres or so I store is sufficient to keep me going for quite a while. I probably only need to run it every 2nd or 3rd weekend unless I’m doing water changes. I can always change it back to automated daily mode if I’m going to be away for a period.

[Tastee]

Thanks all for your suggestions. I am going to fit a pressure limiting valve (hopefully adjustable) and see how that improves things, plus change my automation cycle to avoid running the RODI too frequently.

I’ll post an update in a week or so and let you know how it goes.

[bblumberg]

I had exactly the same problem with my RO/DI unit when I upgraded to a 2nd RO to reduce waste water. I tried changing the ASV, the float valve, etc and could not get the water to shut off or the line to stop vibrating. The solution was to add a check valve to the 2nd RO as well as the first one. Since you appear to have a check valve, I'd change it and see if this helps.

[Tastee]

Originally Posted by bblumberg

I had exactly the same problem with my RO/DI unit when I upgraded to a 2nd RO to reduce waste water. I tried changing the ASV, the float valve, etc and could not get the water to shut off or the line to stop vibrating. The solution was to add a check valve to the 2nd RO as well as the first one. Since you appear to have a check valve, I'd change it and see if this helps.

Thanks for the suggestion. In my case I am not having issues getting the RODI to shut off, it is just the vibration whilst it does so. I have already changed the timing of my system so it can only automatically draw water between 12:00 - 13:00 so that will limit any noise to an acceptable part of the day. The next change will be fitting a pressure limiting valve, so I’ll advise how much that helps when it is fitted.

The vibration is only coming from the inlet side, and as the shut off is operating correctly I don’t think I have a check valve issue. I’ll certainly keep it in mind however.

Thanks, Brad.


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[willembad]

Funny how one guy's problem is another's solution. Mine does the exact same thing and I'm grateful it does since it reminds me that the ATO reservoir is full and I should shut off the supply. I only store 5 gallons and my ATO is gravity fed, so I don't want the supply to keep running. If the float switch in my sump fails I need to know I have more headroom available than what the reservoir can hold.

[Tastee]

Originally Posted by willembad

Funny how one guy's problem is another's solution. Mine does the exact same thing and I'm grateful it does since it reminds me that the ATO reservoir is full and I should shut off the supply. I only store 5 gallons and my ATO is gravity fed, so I don't want the supply to keep running. If the float switch in my sump fails I need to know I have more headroom available than what the reservoir can hold.

I effectively used mine the same way last weekend - turned it on Sat morning after a week being off, and then tapped 27L water for a change inside. Later that afternoon I heard it shutting off so popped outside to turn off the inlet tap.

My ATO is Apex controlled so the volume of stored water isn’t an issue for me, and I do want to be able to run this fully automated when needed, so I’ll continue to try and minimise the noise. Changing the timing of the ATO fill has addressed 90% of the issue however as it will now only occur in early afternoon.


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[Tastee]

Just an update to close out this thread.

I checked my water pressure yesterday and it is 60 PSI, which is right in the middle of the recommended range, so that seems ok. I have now sheathed the inlet line from the tap with hollow core foam insulation (the type used for hot water outlet pipes) to minimise any vibration there, and put some filter foam behind the solenoid to muffle any vibration there.

I tested the system twice today and there was no noticeable noise during shutoff. It may also be that the solenoid has ‘settled in’ a little since initial use.

In normal operation I will manually turn the tap off and only run this once every 2 weeks or so, to replace what I lose due to top ups and water changes. This should give me optimum life from the filters. My ATK has been programmed to only run once a day at 12:00 so that even when I leave the tap on in fully automated mode the RODI will only be producing water once a day.

So the initial problem is now solved, and I have my setup working just the way I need.


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