Pre-heating water to an RO unit

[danoinalaska]

For the RO pros in the forums,,,
Living in Alaska means very cold water coming in from the main line in the winter. My question is this,,,Is it feasible to use an in-line heater prior to an RO unit in order to bring the temperature up to about 70 degrees? Thanks in advance for your reply.
Dan

[jeep]

Thats a good idea. Just don't raise the temp over 100f or you will ruin the membrane. Also, the higher the temp, the higher the TDS...

[Cosmo]

Pre-heating the water will increase the efficiency of the system, and improve the production. Problem is, living in a cold climate (such as Chicago in the winter) the source water is so cold most heaters can't keep up.

I've tried pre-heating with a warm water bath by using 50ft of RO tubing submerged in a 20 gal rubbermaid container w/ a heater and a powerhead before the source water gets to the booster pump. In the winter, the heater doesn't stand a chance of keeping the bath warm against all the cold emanating from the water... even a 300 watt submersible got completely overwhelmed :(

suspect you'll have the same problem with an inline heater

Jim

[RandalB]

He will.

Raise the pressure not the temperature... Pressure makes more difference in efficiency anyway.

RandalB

[danoinalaska]

I was worried that the flow of water through the system would be so slow that it would actually be more difficult to keep the temperature low enough to keep from damaging membrane, not that I wouldn't be able to get to 70 degrees. Does the water really move fast enough through an RO that a heater couldn't keep up?
Thanks,
Dan

[Doug A]

You could use a thermostatic mixing valve. This mixes water from the cold and hot water line. I have one hooked up to the line that I use to fill my storage tanks and feeds my R.O. unit. Water comes out at 82ºF. If you get one you have to make sure that it's a model that is low temp. If I can remember what model I have I'll post it for you, if your interested in going this route.
HTH,

[danoinalaska]

Thanks, Doug I would go that route if it were not for the fact that it would require a lot of plumbing in my particular case (I have only a cold water inlet in the near vacinity) and I may still need to if this inline heater idea won't work.
Thanks,
Dan

[RandalB]

Your RO unit will move almost a liter of water per minute. That comes out to about 15 Gallons per Hour (give or take...) I doubt an inline heater can keep up with it.

Add a booster pump to the system and forget the heating.

RandalB

[danoinalaska]

Thanks again,
But I will be heating, even with a booster the water temp is still the below the membranes optimum range. Thanks for everyones help. I will get this figured out. Best wishes,
Dan

[RandalB]

Good Luck....

RandalB