Help with diagnosing RODI pressure issue.

[dfarr67]

First post- this site seems to have more than it's fair share of rodi expertise- I need some of that.
Have a newer Aquamaxx Puratek Deluxe RODI unit that up until now has performed very well.

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Added a second membrane to it. I have it connected via faucet as I am uncomfortable hard plumbing this in with the pushlock fittings, a mistake was made and HOT water was passed through ot for about 20 minutes. The particulate casing deformed and blew off with granular filter pieces found in various locations inside the unit. The unit operated at 90psi with the single and dual membrane, it is now operating at 70psi which may be sufficient but just wondering what I am missing. Booster pump was pulled apart and looked ok cleaned a bit of filter debris- pump on 70psi, pump disconnected 602psi, on/off solenoid was replaced- had some debris in it- I think the old one is still serviceable, flush solenoid was pulled apart- looks good and bypassed- no difference in psi, all filters and membranes replaced- with close but not exact replacements, plastic filter casing replaced, pump deadheaded and showed 150psi, new gauge installed- similar reading. The booster pump is not adjustable- I have not looked at it in detail- I suspect the pump is slightly compromised- what else is there- fairly simple when digging but I have little experiance. The 400 waste water orifice seems to be simple enough. Without checking I believe the original membrane was 100gpd, the replacements may be 90gpd.

 

[JumboShrimp]

Welcome... let’s try to get you an answer!

{BUMP}

 

[Reef.]

Could be loads of different issues with so many repairs being carried out

You say 70psi maybe enough, have you not tried yet? Are you getting zero TDS?

couple of suggestions,

membrane damaged, flow regulator incorrect size for membrane or damaged, pressure not enough for two membranes.

Hard to help as I'm not sure exactly what the issue is as it's not clear to me from what you have wrote.

Is the unit not producing water, is it too slow, are the TDS not zero?

 

[dfarr67]

Thanks for the replies. After the incident- zero ro water production, zero psi, I can't recall waste being produced. Unit is producing water now fine with zero TDS- pressure was 60psi with new membranes, I reinstalled old membranes pressure increased to 70psi, zero TDS.

 

[JumboShrimp]

Sounds like you made a nice recovery; good job!!

 

[dfarr67]

Still wondering where the 20psi went? And why so little difference (8psi) with booster pump not running vs running.

 

[Hallowhead]

I don't know if it was mentioned, but maybe debris were clogged in the RO tubing? The membrane could have deformed from the hotter water causing less water to pass through?

 

[Snoopy 67]

Flow restrictors are membrane specific as to GPH.
Difference can cause problems but that's only my guess.
Try Russ @ Buckeye Hydro for a better answer.
Hot water in an ro unit is a NO - NO as you have found out.

 

[dfarr67]

I don't know if it was mentioned, but maybe debris were clogged in the RO tubing? The membrane could have deformed from the hotter water causing less water to pass through?

Not sure which way that would go- when the unit was new it ran 90psi, even with new membranes it was running 60 psi- model number on new membranes include 100 which I assume is 100gpd.

 

[dfarr67]

Flow restrictors are membrane specific as to GPH.
Difference can cause problems but that's only my guess.
Try Russ @ Buckeye Hydro for a better answer.
Hot water in an ro unit is a NO - NO as you have found out.

Not just hot- is was HOT. Really ticked me off- attention drawn by something else. Not a cheap unit either. Anyway- is was an acciddent, but I prefer learning from other peoples mistakes

 

[Buckeye Hydro]

Yeow. There's a lot of info here... some seems contradictory, and I'm not sure I can follow it as written. What specific parts have you replaced?

Russ

 

[Buckeye Hydro]

FYI - the "90 gpd" membranes sold into this hobby are relabeled 75 gpd membranes.

 

[dfarr67]

Wrote it last night+ heat wave here= not coherent
Some parts supplied by vender:
- new solenoid valve, main on/off valve (runs VERY warm- but I guess it is always energized when unit is running. Old valve had some debris inside pintle will keep it as spare.
- new high pressure switch, installed just because they sent it out- I don't use a float valve option, I just fill 5 gallon jugs as needed.
- new pressure gauge- to see if the old one was off- very similar readings- waiting on a fitting to use old gauge on water supply side.
- new plastic filter housings two of the three (one blew up second was slightly deformed but usable), new DI, carbon, sed filters, new 100gpd membranes (switched back to old ones (they were 3 months old) just to 'see'- just a bump in psi which I see as a positive.
- If the 'problem' stems from a different than oem membrane- I'm fine with that explanation, just educating myself on new gear and if there is an issue I haven't looked at. the restrictor is so simple I thought it may be missing parts- seems to be an orifice in a tube- that's it. I thought about simplifying a little bit with the combo restrictor/flush valve in one unit.

 

[Reef.]

Still wondering where the 20psi went? And why so little difference (8psi) with booster pump not running vs running.

booster pumps are limited, they don't boost an already high pressure system, sounds as if your pressure is good without the booster, so the booster will only increase that slightly.

Think you said you reduced the membrane size, did you replace the flow restritor to match it, the previous one could have been damaged and they also really need replacing with a new membrane, that could account for a drop in pressure.

Were do you have your booster pump? It should be just before the membrane not at the start of the system.

 

[dfarr67]

Spec claims it comes with this membrane: Pentair 100 GPD membrane. I'll pull it and check it- I reordered decent quality 100gpd replacements. The piggyback kit I added might have come with a 90gpd membrane. The system is prebuilt modular design- the pump is where Aquamaxx designed it. Everything was working fine before the hot water was run through it.

 

[Buckeye Hydro]

The most popular booster pump on the market, the Aquatec 8800, will handle up to 120 gpd membrane. You can make it work with 150 gpd (or two 75 gpd's) if you configure the system correctly. Looks to be a non-aquatec pump on that unit... so no telling what it can handle.

Some other things I noticed at a quick glance:
Uses pentair 100 gpd membrane at 1.5:1 ratio. The pentair membrane is spec'ed at 65 psi, rather than the Filmtec 50 psi. This membrane has no magic powers to be run with that little bit of concentrate flow. In fact, it is factory spec'ed to run at about a 5.6:1. You can take any RO system and choke off the waste water... but in most instances there is a price to be paid for doing that.

The product description describes a "BACK flush" function. You should never ever "back" flush a membrane - you will irreversibly damage the membrane if you run water backwards through a membrane.

Although the membrane manufacturer spec's the membrane at 98% rejection, the RO system description claims 99% rejection.... Hmm. More of that magic I guess.

Not that it affects the system, but the description mentions "canisters." If you ever hear anyone call a filter housing a "canister," take that as an indication you are unlikely to be dealing with a water treatment professional. They also use the term "Main rejection." There is no such thing. I assume they are referring to the membrane rejection rate.

The feedwater solenoid is not a latching solenoid. Less than ideal.

The RO membrane housing is configured to have the permeate and concentrate ports at the bottom position. The concentrate line will cause the RO membrane housing to drain. You may have heard that once you wet a membrane you need to keep it wet. Again, hmm.

These sorts of things cross my mind every time I hear people saying "RODI systems are all alike..." No, I can assure you, they are not.

Russ

 

[dfarr67]

Well I am open to suggestions to make it work better.....the 'flush solenoid' just bypasses the flow restrictor- don't know what that effectively does.

 

[Reef.]

Well I am open to suggestions to make it work better.....the 'flush solenoid' just bypasses the flow restrictor- don't know what that effectively does.

if you mean the flush on the membrane, it flushes the built up TDS particles on the outside of the membrane as it's used, so instead of them going into the resin they are flushed out bypassing the resin so prolong ping it's life.

 

[KStatefan]

Call Russ @Buckeye Hydro

The flush valve that bypass the flow restrictor is designed to keep the concentration of hard water to reach the insolubility point and form scale on the membrane. I doubt there are many if any home systems that it does anything. It does not remove TDS creep.

 

[dfarr67]

The most popular booster pump on the market, the Aquatec 8800, will handle up to 120 gpd membrane. You can make it work with 150 gpd (or two 75 gpd's) if you configure the system correctly. Looks to be a non-aquatec pump on that unit... so no telling what it can handle.

Some other things I noticed at a quick glance:
Uses pentair 100 gpd membrane at 1.5:1 ratio. The pentair membrane is spec'ed at 65 psi, rather than the Filmtec 50 psi. This membrane has no magic powers to be run with that little bit of concentrate flow. In fact, it is factory spec'ed to run at about a 5.6:1. You can take any RO system and choke off the waste water... but in most instances there is a price to be paid for doing that.

The product description describes a "BACK flush" function. You should never ever "back" flush a membrane - you will irreversibly damage the membrane if you run water backwards through a membrane.

Although the membrane manufacturer spec's the membrane at 98% rejection, the RO system description claims 99% rejection.... Hmm. More of that magic I guess.

Not that it affects the system, but the description mentions "canisters." If you ever hear anyone call a filter housing a "canister," take that as an indication you are unlikely to be dealing with a water treatment professional. They also use the term "Main rejection." There is no such thing. I assume they are referring to the membrane rejection rate.

The feedwater solenoid is not a latching solenoid. Less than ideal.

The RO membrane housing is configured to have the permeate and concentrate ports at the bottom position. The concentrate line will cause the RO membrane housing to drain. You may have heard that once you wet a membrane you need to keep it wet. Again, hmm.

These sorts of things cross my mind every time I hear people saying "RODI systems are all alike..." No, I can assure you, they are not.

Russ

Yes, most communication with the manufacturer and the vender has been met with disappointment- the only bright spot was Marine Depot who is somehow in the mix. Some pics attached.