Filter system for my Alex Duetto II - Page 2

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godshot

#11: Post by godshot »

I beg pardon for barging in on this thread to ask a similar question about a filtration setup. I hope I'm not being rude.

I'm building a filter system under my sink too, and I'd like to know if the arrangement I'm planning seems reasonable.

Full house pressure input to:
- ball valve shutoff to isolate entire downstream filter system
- inline check valve at entrance to first filter to prevent back flow
- 10 inch sediment filter (10 micron)
- 10 inch carbon-block filter (1 micron)
- Tee to two outputs
- output 1 to drinking water faucet (terminus)
- output 2 to ball valve to isolate remainder of system
- pressure regulator to reduce pressure to 35 psi
- water softener
- espresso machine (terminus)

The reason for having a separate sediment filter is to protect the carbon-block filter. Several times a year we get heavy sediment flows, especially after local water system repairs. The filter housings both have pressure relief buttons, so I don't need a valve between them to dump pressure.

The path to the drinking water faucet is full line pressure all the way. Shutting off the ball valve on output 2 will allow me to flush my carbon-block filter through the drinking water faucet (thanks for that idea Dan).

I presume that the pressure regulator could go on either side of the water softener. Putting it before the water softener will reduce the number of non-NPT fittings I have to deal with. 35 PSI is 2.4 bar, which is greater than the 1 bar minimum pressure required by the water softener.

The water softener has its own built-in flush valve.

Does this sound reasonable?

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HB
Admin

#12: Post by HB »

Sounds reasonable to me. The addition of a check valve is a good idea, but keep in mind a pressure regulator also acts as one.
Dan Kehn

godshot

#13: Post by godshot »

Thanks, then perhaps I'll eliminate the check valve.

How can I accomplish descaling with this setup? Would it be sufficient to disconnect the water line at the output of the water softener and just put the end of the line in a bucket of citric acid solution? It wouldn't be under pressure, but the pump would already be primed with water.

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Marshall

#14: Post by Marshall »

godshot wrote:I'm building a filter system under my sink too, and I'd like to know if the arrangement I'm planning seems reasonable.
Since you are designing your own system, I would add a bypass in the final stage with an adjustable valve to mix softened and unsoftened water, so you can customize the hardness of your brewing water. Commercial systems often have this feature built in.
Marshall
Los Angeles

godshot

#15: Post by godshot »

So would this be a tee between the pressure reducer and the input side of the water softener, and a valve at the mixing point on the other side of the softener? Would you use a gate or ball valve and just test the mixed water for hardness periodically, or is there another type of valve that would help measure the mix? I guess I'd need a way to sample the water at the mix point too.

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Marshall

#16: Post by Marshall » replying to godshot »

If I knew what any of those things were, I would give you expert advice. Mine (Claris) has it built in.
Marshall
Los Angeles

genovese

#17: Post by genovese »

Thanks guys. Dan, the purge-via-faucet is an elegant solution. I was initially ambivalent about even having a faucet, since the selection at the DIY chains was either junk or way overpriced. Then I realized that I could order online a complete kit with decent bundled faucet at a very fair price. I settled on a Watts 2-stage that got a mediocre review in Consumer Reports, only because flow was slow. If that becomes an issue, I figure I can buy generic 10" cartridges to tailor it to my liking. I have only 5-6 grains of hardness, so I'm more targeting chlorine, lead, organics and the never-ending rain of rubber washer crumbs from the many ancient and neglected stop valves in my basement.

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genovese

#18: Post by genovese »

godshot wrote:So would this be a tee between the pressure reducer and the input side of the water softener, and a valve at the mixing point on the other side of the softener? Would you use a gate or ball valve and just test the mixed water for hardness periodically, or is there another type of valve that would help measure the mix? I guess I'd need a way to sample the water at the mix point too.
Ball and gate valves are best used as shutoffs. Their flow response is non-linear, at lot at small openings, much less otherwise. Wear and noise can occur at small openings also. Globe valves are better for adjusting flow. Going strictly off-the-shelf, you could cobble two valves and a tee into a mixer I guess, but commercial RO systems use bypass valves which might also function as differential mixers, whether by design or user cleverness. 8)

godshot

#19: Post by godshot »

Thanks for that info genovese. I don't understand how a bypass valve works. But a globe valve, or maybe a needle valve would work. You'd have to test the water periodically and adjust the valve to control the mixture. Tedious.

I found that there are a number of inexpensive mixing valves, but they are thermostatic valves, which is not helpful in this application. There are also solenoid operated valves, like the ASCO 8256 NSF-certified potable water solenoid valves, but I believe they are just on or off, not proportional. Also not helpful.

For now I'll just leave a stub in the line that I can build out later if I find I need to. I'll have to search the forum to see how others have managed this.

genovese

#20: Post by genovese »

HB wrote:Sounds reasonable to me. The addition of a check valve is a good idea, but keep in mind a pressure regulator also acts as one.
A belated qualification just came to mind: for many (I can't quantify "many") PRVs this is true up to a point, i.e. the point when the low-side pressure exceeds the high-side pressure, which is when backflow is enabled. An example is the Watts N45B, whose literature says "the standard bypass feature permits the flow of water back through the valve into the main when pressures, due to thermal expansion on the outlet side of the valve, exceed the pressure in the main supply." They're talking about thermal expansion generated by a household water heater. As I accidentally found out, that can be a very big deal, big enough to deserve its own thread....