Thread: CSV1Z to adjust pressure for GE Merlin R/O

My GE Merlin reverse osmosis system works well at 40 psi and above.

The problem is I have about a 6 to 10 psi drop through my acid neutralizer and ion exchanger, so I need to set pump cut-in at 50 psi to get a minimum of 40 psi to the Merlin (depending on fixture usage and flow). I don't really like the 50-70 psi range this produces for the house (all 3/4 and 1/2 CPVC). The 70 psi static pressure after cut-out just makes me nervous.

Now I could buy a booster pump for the Merlin but they are ++$$ more than a CSV. Another option; boosting pressure and isolating the Merlin by installing PRVs to the rest of the house is not practical.

So my plan is to set cut-in at 50 psi (for the Merlin)and cut-out at 60-ish psi (for my peace-of-mind), then set the CSV1Z at 55 psi.

As I see it, the showers will get nice steady pressure, the Merlin will never see less than 40 psi, and the pipes will only see 60 psi after the pump cuts out (static pressure).

I am planning to use a 22 gal Flex-Lite FL-7 so the drawdown at that pressure should be around 4.5 gal for quick pump/CSV activation. Then when the pressure tank fills, the CSV should run full throttle to 55 psi and then throttle to 1 gpm for another 90 seconds or so, cooling the pump. (Its an 8 gpm Aermoter, but it's 20 years old and probably closer to 6 gpm.)

So does using the CSV to set a narrow pressure range seem like a sound idea?

You and I haven't agreed on much to this point. I don't like RO's for several reasons and don't really know why anybody would want one unless they have salt water running from their taps.

Seventy pounds is not too much pressure for any type of household plumbing unless it's 50 + years old. Then I might be a bit suspicious. Most leaks in homes occur from pipes rotting or dissolving. Like galvanized that is just so old that the galvanizing gave out and the pipes started rusting through. Or the coppper pipe was eaten by the chlorine from the city water or by the low PH that some water has. Pressure by itself won't hurt the plumbing.

Another problem with your idea is that unless you want to spend a lot of money on a special pressure switch, 17 lbs is about the smallest spread your going to be able to get with most of them out there.

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I agree 50/70 won't hurt anything, that is what I have at my house. I also agree that 17 PSI, sometimes 15 PSI is about the minimum differential you can get with a Square D switch. Also if you can get to 10 PSI differential, that would cut the draw down of the tank in half but, still not a problem with the CSV.

Cycle Stop Valve Website

quote:Originally posted by speedbump

You and I haven't agreed on much to this point. I don't like RO's for several reasons and don't really know why anybody would want one unless they have salt water running from their taps.

I use internet forums to exchange helpful info. If I wanted disagreement I'd just go to my Mother-in-Law's

So I don't prefer to explain or defend the RO unit. Maybe my feed pipe is stuck into the Atlantic ocean!

I am looking to buy a CSV1Z though, so you might want to consider how your assumptive response may motivate a potential customer. [:u]

At any rate I do appreciate both of your responses regarding the safety of 70 psi and Square D switch range.

I'll experiment with the switch range and then use the adjustability of the CSV1Z to trim everything out for adequate drawdown and pump run time.

I'm looking forward to the project and will post the results.

Thanks again for the forum.

quote: If I wanted disagreement I'd just go to my Mother-in-Law's

That's one of the things I like about owning a Forum. I have the right to say what I want. When someone comes in here acting like they know more than I do, then ask for my advice it rubs me the wrong way. I have never been one to mince words or take much lip from anyone. So as you can see, you slightly ruffled my feathers.

The other side of the coin is that you have the right to your opinion as do I, so just because you came here doesn't give you the right to tell me or anyone else how they should act or respond to your request. The promise of a possible sale is no way to win friends or influence people either.

We can agree to disagree if you like about RO's and other things. Like I said, everyone is entitled to their opinion and they are perfectly within their right to post it here as long as they don't get too combative.

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quote:

..... and they are perfectly within their right to post it here as long as they don't get too combative.

Boy, that's good advice.

The concept of the Merlin is a fine one...on paper. We, too, have had unfortunate experience with them. Pretreatment is essential and maintaining high influent water pressure is a must. The membranes are large enough to have a flow rate of nearly 1/2 gpm with about 60psi (recommended). But they are expensive to replace (about 65% of the new price).

ROs are a wonderful way to improve drinking water and I recommend on either city or well water applications.

Andy Christensen, CWS-II

Well, I was trying to show that I had done my research, arrived at some possible conclusions and was asking if they were valid. No ruffling whatsoever was intended. If I thought I knew more than you I wouldn't be seeking opinions here. So I apologize for the customer comment.

But I try not to make the kind of posts (we've all seen) that start with something like: "HELP, there's water EVERYWHERE!!!" Research is our friend.

On other forums I assist people with auto repair. It matters not to me if they drive a Hummer or a Prius. That's not my call to make. So I did not mean to make the Merlin a point of debate. I've had the thing for 10 years and am familiar with its pros and cons.

I'm not pushing ROs, just trying to fit a CSV into my application.

quote:But I try not to make the kind of posts (we've all seen) that start with something like: "HELP, there's water EVERYWHERE!!!" Research is our friend.

I do appreciate that, and it's what we would like people to do. As a friend of mine says quite often to others "Google is your friend". What he meant by that comment was: "Quit asking me all these stupid questions and do a little research on your own". We both have one aquaintance that does this all the time and it drives him nuts.

Getting back to your pressure dilemma. You could simply raise the settings on the pressure switch to get the higher pressure you desire. The CSV is a device I recommend for any pump system that can make more pressure than is needed for normal water usage. This keeps the pump from cycling, gives you the constant pressure you desire and does it quite cheaply.

The reason I don't like RO's is that a lot of people forget that they require maintenance. They have them installed, use them for years, allow bacteria and all kinds of other nasties to accumulate in the filters, then start actually getting worse water than they would have without the RO in the first place. This is human nature. Install it and forget it. The other reason is that the RO and a Water Softener/Iron Filter take out minerals that are actually not just good for you but required for good health. So if you don't take supplements to make up for the removed minerals, you body suffers. Thank God those minerals can also be found in Beer.

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What I have against ROs is the fact that the vast majority of people that have one, don't need it.

And yet you have salesmen pushing them as if everyone needs one. Like our resident Kinetico salesmen Andy. He suggests their latest and greatest K5 for $1000-$1500.

Gary
Quality Water Associates
www.qualitywaterassociates.com
Softener Forum

Wow, and I can buy a 30 gpd unit for somewhere aroung $125.00 last time I priced one. There is nothing magic about them. They just remove all the good things from your water.

I just never could understand the hype about bottled water, but everyone in the nation drinks that crap (except me) and the RO's carry the same stigma. Your tap water is polluted so buy this. It is tap water for cripe sakes.

The only people in my area that need an RO are on two streets in a little neighborhood not too far from a river. For some reason they have salt water. So they have whole house RO's. I installed one for a customer of mine years ago. I sold another large one for a Fish Farmer customer who needed pure water for some kind of fish he was raising. Otherwise, I don't see the need.

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