I am trying to figure how to replace a 3M Aqua-Pure AP431 / AP430SS Scale Inhibition Water Cartridge (on pipes feeding my tankless boiler) that had previously been replaced by my plumber. I'm confused b/c the directions say: “Shut off inlet (Stop and Waste) and outlet (Compression Gate) valves. Open drain on inlet valve, to relieve pressure in the AP430SS.” I’ve attached a photo below. I had just assumed I needed to turn off the green valve, which my plumbed installed last year, and the red valve to the right of the cartridge, but I was confused about how to open the drain on the inlet valve, so I contacted 3M/Solventum, and they told me “the plumber did not use the correct valve.” I don't know which valve 3M was referring to, but they circled instruction 3/figure 3 in the installation instructions (p. 4) here:
[multimedia.3m.com]

Can you please advise how I can replace the cartridge now and whether I should hire a plumber to install different valves? thanks!

Turn off the red valve on the inlet side, relieve pressure in your water pipes by leaving open a faucet, close the two valves on the outlet side and change the cartridge. No need to redo anything.



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thanks for your help, George! do I continue to run the water when I remove the old cartridge, or do I turn off the water before I remove the old cartridge?

also, after installing the new cartridge, the instructions say: "Turn on inlet valve and bleed air through gate valve drain until water appears. Then close drain, and open outlet valve."
so I turn on the red valve on the right [that's the inlet valve, right?], but can you please explain how I "bleed air through gate valve drain"?

thanks!

You don't need to run water after you have turned off the two valves on the outlet.
Yes, the inlet valve is the red one on the right.
The filter assembly will be bled of air once all three valves have been opened back up and water run thru the filter.
That is the way I see it. The 3M instructions are a bit odd, specifying a compression inlet valve and a gate valve as outlet. Someone else please chime in if I am missing something.

i haven"t used either type valve in years.

BTW.. i don"t like the location of the green relay. looks like a valve located right above it.

thanks for clarifying, George!

packy, my plumber installed the green valve b/c when he previously changed the cartridge, a lot of water leaked. The green valve is right below the cold water hose, and the right valve is also near a similar cold water hose, so I'm quite confused why everything is set up like this.

Packy was referring to the green relay box in the lower-right of the photo, which contains electrical components, being located below a valve which could leak water down into the electrical. Sloppy and potentially dangerous practice unless absolutely necessary, and even then could have been done more safely. The relay box appears to have openings on the top.