[Samper]

I didn't come up with this but I thought that it was interesting. Here is what was posted.

About a month ago when the first big cold blast came through, I received a call from one of the NEA members in regards to his RO/DI system that was putting out substantially less product water, while also having a decreased incoming pressure reading... At the time, I wasn't thinking too clearly due to my current medical condition and daily handful of (at that time) narcotics, but over the past few days I've noticed my system has also dropped from the usual 90psi to 70psi, thus resulting in a trickle, rather than a stream of product water.

Being that I had a very rough night last night and ended up on the couch unable to sleep, then heard my damn AATOC tripping every couple of minutes, I realized I had to resolve this issue before it drove me insane!

*B A M*

70psi is now back to 90psi, and the water is once again flowing as it did before the cold blast arrived.

It's basic fluid dynamics, in that warm water flows better than cold water, so by blending in a bit of hot water (72-75 degrees overall temp) it penetrates the filters and membrane better, which allows for the increase in product water. The increased water pressure, boosts the line pressure, and a performance increase of 20-25% was achieved in minutes.

BTW: The rating on RO membranes, is a factory lab rating assuming an incoming water temp of 72 degrees, but what they don't tell you, is that you lose 1.3% of the spec rating for every degree below 72 degrees!

Being in the south, this is purely a seasonal situation, and in fact, I never saw the decrease in pressure last winter, nor do I recall it being this cold. This method is ghetto at best, but is a viable solution for the short-term use that we would need in this area... It's not a new idea either, because several years ago I invented the "RO Buddy", which is a more permanent, year-round solution that was pretty much essential for those of us that lived up north.

Just be sure to keep the COLD line wide open, and adjust the HOT line until the desired temp and pressure are reached. You'll need to allow at least 15 minutes for your RO membrane to come up to temp, then another 5-10 minutes in order to get a stabilized enough temp reading from the product water. Also, you'll notice from the pic below, that the COLD water gets a straight pass, while the HOT water is injected into the stream.

Temps in excess of 90 degrees can ruin your RO membrane, so caution must be used to not go above 80 degrees as a safety barrier.

[jsheffel]

Those are obviously your washing machine valves. Where did you find ones with a "secondary outlet" to hook your RO/DI feed lines to?

[jiggly75]

Originally Posted by jsheffel

Those are obviously your washing machine valves. Where did you find ones with a "secondary outlet" to hook your RO/DI feed lines to?

You can get them at lowes or home depot.

[Ixthys]

I don't understand how the RO buddy regulates the temperature. Could you please explain?

I often add in hot water to the input line of the ro/di, but I find it impossible to accurately control the temperature. Especially when the wife starts up the washing machine,etc.

[rjs5134]

Actually, it looks like standard washing machine valve with two standard hose bib splitters. The washing machine valve doesn't have a secondary outlet, just primary, but the splitter is pretty easy to find at just about any hardware store.

Great info Samper, my cold water supply is down to low 60's at best right now. Looks like another project for this weekend... When will it end???

[Ixthys]

click on the link he posted

[Samper]

I'm not sure how it works and I'm not advertising the reef buddy. I was more interested in the hot/cold combo for the quickest/best way to filter the water.

[jsheffel]

Originally Posted by rjs5134

Actually, it looks like standard washing machine valve with two standard hose bib splitters. The washing machine valve doesn't have a secondary outlet, just primary, but the splitter is pretty easy to find at just about any hardware store.

I see the splitter now (makes much more sense). Are the reducers to go from hose bib to 3/16" (or whatever size the small tube is) commonly available?

[Samper]

Those reducers fit 1/4" OD tubing.