Refurbishing The GE Merlin Tank-less Reverse Osmosis Filter

Last week, I posted regarding my plans to refurbish my GE Merlin tank-less Reverse Osmosis filter. Just as a reminder, it puts out 1 gallon of purified water per minute on demand, so there’s no need to use a tank. It’s a hefty system, taking up a lot of real estate under the sink, more so if you add a DI filter (like I’m doing). On the other hand, I had great service from the filter when I lived in NC, so I brought it with me when I moved. My wife is ready for me to put it into service in order to enjoy the convenience and health benefits of having RO on tap in our home!

Last weekend, I ordered the components I needed, then removed the old membranes and pre-filter. I actually had a sediment pre-filter (instead of charcoal) because the municipal water supply in Leland, NC was rich with minerals. Hard water, in other words. Here in Boca, the water, by contrast, is rich in chloramides. This makes a charcoal pre-filter an absolute necessity, as chlorine will destroy an RO membrane in short order. Knowing your water is the first step in knowing how best to filter it. While Boca water also has an abundance of minerals, I plan to address that very soon with a whole house filter that pre-treats water before it enters my home’s supply. That’s where I plan to install the smart shut off valve for the home, so I need to do a little more research before I start that project.

First, I needed to clean the housing. I took everything apart and soaked it in 5 gallons of water mixed with 1 gallon of chlorine. After soaking for an hour, I brushed all the surfaces clean and rinsed the components with a high pressure nozzle (see below). If you don’t have a nozzle like that, you can go to the local car wash or use a pressure washer on its very weakest setting. Afterwards, I soaked the housing parts for another hour in water and repeated the heavy rinsing. Chlorine is great for cleaning, bad for membranes, so try to get rid of all you can. It will evaporate over time, but you don’t want to leave a film, either.

Here’s the cleaned and dry housing, ready for assembly. Please check out your O-rings. This filter works best at 60 psi or more, so PLEASE make sure that your o-rings aren’t stretched, there are no nicks, and there’s no discoloration that could indicate that they need to be replaced. These are still in excellent condition, so I’m re-using them. Also, please note the darker of the two “legs.” The large hole is actually a wrench for the three white canisters on the right (which screw into the light gray “leg” on the left).

The charcoal filter pictured here is not rinsed, yet (rinsed later) – you can rinse or skip rinsing, but remember that any charcoal you don’t rinse from the filter will end up in your membranes. Both sides of the filter are the same, with a rubber seal to help seat it. You can install this cartridge in either direction.

The RO membranes are vacuum packed because they’re shipped wet. Don’t worry, you’re going to flush the RO unit for at least 15 minutes when it is assembled, so any “stale” water from the membranes will be removed. There is a large o-ring built in as a color on the membrane, with two small o-rings on the neck. You can only install this cartridge in one direction as you’ll note when you see the picture of the housing interior. Once you’ve got each cartridge installed, tighten the housing before moving to the next, then put the “leg” on to support it.

All done!

I’ve got a box of quick connects and flexible PVC tubing for the plumbing side of this project. Also, when I did the tear down and cleanup, I found that some sort of goop had contaminated the deionization filter chambers. The cost of new resin and new cartridges would cost the same as buying a new pre-assembled DI unit with resin included, so I ordered one of those, which is the last part needed for the project. If things work out, you could see the next (and final) installment of this project next weekend! is the website for our Facebook community, The Smarter Home Club – which is an umbrella for all kinds of smart home technologies – home automation, security, custom electronics, weather stations, alternative energy, you name it. DIY focused.

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