DIY RODI water heater

[RacinRevo0818]

So I have been noticing my rodi water production has really been affected by the colder winter weather. I had been reading up on how the rodi system will perform best when water temp is 77 degrees, I have well water so I can't even expect that in winter. So I was reading that warm water ran thru your water heater is a big no no, so I figured I would just live with having a rediculas amount of waste water. Then I ran across an article that had mentioned making a simple hot water heater. I beleive they credited Melevs reef for the idea but I couldn't find the article. So I figured I would take some shots of how I made mine. I also included a break down of cost and tools needed.
Drill 2- 1/4 inch holes in top side of bucket for 1/4 tubing fits tight
Drill 1- 1 1/4 hole in top of lid for heater
Feed tubing through the 2 holes and spread the 25 feet of tubing as best you can in the bucket
Install 90 degree elbows onto tubing
Drop the heater in the top hole
Cut water supply line to rodi and insert fittings.
Plug in heater and enjoy!!
Fill the bucket full of water and set temp to 77 degrees, worked perfectly.

5 Gallon bucket $3
Lid $ 1.50
25 feet of 1/4 inch tubing $2.50
2 90 degree 1/4 elbows $6
Eheim Jager 150 watt heater $22 if you dont have one lying around

Tools required
Drill
1/4 inch drill bit
1 1/4 inch drill bit
Razor blade

 

[RacinRevo0818]

Before and after pictures

Here is cold water out of tap 58.9 degree's

Here is the temp after 76.8 degree's

I have not had a chance to check the ratio of waste to good rodi yet but I can tell by the amount dripping into my container it has improved greatly. If you have any questions fill free to ask.

 

[jelly]

do you use a pump on your rodi.. cause with a pump it will move more water through the system so the water temp might not rise as high..

 

[RacinRevo0818]

No I do not have a pump the water pressure from well is about 60 psi.

 

[jelly]

i love the idea i just wounder it it will heat water fast enough for my rodi.. i run a pump to boost my pressure up to 70lbs and its making about 75g aday

 

[redfishbluefish]

I really like this. I’m in New Jersey and had to start mixing hot and cold water to minimize waste about two weeks ago. I’ve also heard about not using water from a heater, but I can’t figure out why it would be any different than tap water, short of a zinc anode in the heater releasing a smidge of zinc ions.

I now have a project for this week. You just need to plug the heater in an hour or so before you start making water.

Thanks for posting this DIY. Good stuff.

 

[RacinRevo0818]

i love the idea i just wounder it it will heat water fast enough for my rodi.. i run a pump to boost my pressure up to 70lbs and its making about 75g aday

I would say you can increase the temp of the water in the bucket until you reach the 77 degrees leaving your RODI unit. Shouldn't be a problem considering 150 watt heater and less then 5 gal of water. Post your results if you end up doing it!!

 

[AZDesertRat]

RO membranes DO NOT work better at 77 degrees, in fact they work better with COLDER water.
77 degrees is a benchmark or standard all the membrane manufacturers chose so membranes can be easily compared to each other.

Colder water is more dense so treats better than the more fluid warmer water which passes through the membrane better but also carries more contaminants with it. The colder denser water will give you a lower treated TDS so is a better choice. If GPD is really an issue, which it usually isn't with a 75 GPD membrane, then a booster pump is a much better choice as the additional pressure will overcome the effects of the cold water without sacrificing the lower TDS and longer DI resin life. I would much rather have cold water myself!

You will also find the cost of energy to run the heater is prohibitive and not the least bit efficient. Plastic tubing is a horrible conductor of heat and cold so the transfer or heat exchange is almost nil. This has been tried and dicounted hundreds of times, its the same as trying to make a chiller out of a coil of plastic tube and a dorm refrigerator, it just does not work well or for long. A 150 watt heater is designed to run intermittently and heat a constant amount of water, not water that is circulating through and carrying the heat away. Sorry.