Heating RO water - Orchid Board

dot · #1 09-17-2009, 11:29 AM

Here's the situation:

We are planning to build a "conservatory" (for orchid growing now, and later for anything whoever has this house after us). We've looked into using our well water -- too high in calcium and iron, bringing in water from our pond -- too expensive, and now we are thinking about an RO system. Likely this system would be in our basement with a hookup to the conservatory. In our basement, the water would be too cool to use directly.

So we need to heat it some way. But our heating/plumbing guy says he cannot find an appropriate heater because of the caustic nature of pure water.

How has anyone else solved this problem?

Ross · #2 09-17-2009, 11:46 AM

I heat RO water all the time with no issues. My situation is different than yours, though. RO water is not "caustic" per se. It is "pure" water. It should have zero effect on heaters since by nature it contains no additives or minerals. It would be similar to heater rain water. If it were me, I would simply heat the water as I would any other water - except, you will see NO build-up of minerals.

dot · #3 09-17-2009, 11:56 AM

Ross, you have a heater in your storage tank? May I ask, what kind is it?

Or does the RO water pass through a heater?

Ross · #4 09-17-2009, 05:12 PM

No I don't have a heater per se. I heat the water (when needed) on a stove. While your need is larger, the point is still the same: RO water is NOT caustic. Any water heater should work fine. Contact Ray at Firstrays.com as he has a large greenhouse and uses RO water. He should confirm the non-caustic opinion (I think).

Des · #5 09-17-2009, 05:25 PM

I use an aquarium heater works fine for me

dot · #6 09-17-2009, 09:37 PM

Quote:

Originally Posted by Des

I use an aquarium heater works fine for me

Des, are you using RO water in a storage tank with your aquarium heater?

Des · #7 09-17-2009, 10:23 PM

dot, I am heating rain water which is about 7 to 10 degrees C to 18 to 20 Degrees C any higher will be problematic as it will drive off the dissolved oxygen.
In the summer months I cool the water in my storage tanks to 20 C

dot · #8 09-19-2009, 11:24 AM

For Ross: please note #3: Reverse Osmosis Basics

Thanks, everyone.

quasi-starfish · #9 09-19-2009, 11:56 PM

I have an RO/DI unit for my planted aquaria. I run the RO water into a 44 gallon plastic (Rubbermaid) trash can. I heat it there using an aquarium heater. I also have a powerhead to drive off the CO2. Sometimes I also use an airstone. So, the water is stored in the trash can where it is aged and reaches the correct temperature.

Incidentally, I have a delivery pump also that pumps the water (city pressure about 45psi) through the RO device at the optimal pressure (for my unit, about 60psi).

Then, I have a hose that runs from the trash can through a demand pump that pushes the water through a DI unit and then through a hose that goes directly into an aquarium. So when I want to refill a tank, I simply plug in the demand pump.

Some parts of this unit could be made more automatic, in principle. For example, a float on the trash can could turn off the RO fill when the trash can is full.

nhman · #10 09-27-2009, 04:09 PM

I have my R.O. water running into a 50 gallon plastic barrel. The level is controlled with a float valve to shut off when volume is reached. This is then heated with a submerged aquarium heater to 70 degrees. A demand submerged pump then can pump out the water as needed for my orchid watering purposes.