RO/DI... heating inlet water?

[Jandree22]

Is anyone warming up their inlet water to their RO/DI? I saw the idea that Melev is credited for 'inventing' with taking the inlet tubing and coiling about 25-30 feet of it in a heated 5 gallon bucket of water to raise the temp by the time it enters the unit. Same principle, but I was actually going to coil it up in my 30g fuge which is at 79*F anyway. My water is coming in at 45-50*F right now, wondering if this method is really capable of getting well into the 70's in enough time? Just looking for any experiences with this...

Alternatively, does anyone just mix hot/cold water lines for the inlet water?

My house already has low pressure @ 36psi, so that mixed with the cold temp is giving me less than stellar production rates.

 

[smleee]

Re: RO/DI... heating inlet water?

<a href=showthread.php?s=&postid=14471188#post14471188 target=_blank>Originally posted</a> by Jandree22
but I was actually going to coil it up in my 30g fuge

Already being done; works just fine!

<a href=showthread.php?s=&postid=14471188#post14471188 target=_blank>Originally posted</a> by Jandree22
Alternatively, does anyone just mix hot/cold water lines for the inlet water?

I do; just be careful of the input temp on the hot; too high will melt your membrane. I connect mine to the faucet for more control. My advice if you do so is before connecting, run the "luke warm" water out of the hot line. Otherwise you will get "hot" water after 15-20 minutes (once the luke warm is out). Then adjust the faucet with the cold side and make it warm.

 

[RokleM]

Honestly don't bother wasting your time with heating the water via cold/hot mixture. Your bigger issue is not the temperature.

The water in a bucket idea is even more ridiculous. Think through these questions and you'll see why. How cold is the water? How many watts would you have to use to keep that bucket cold? How much PSI do you waste with all that extra tube? How quickly does the water go through that 25 foot? How long before the bucket is fully cold and your return is zero?

I tested it a while back. I even went a further step and did 50 foot in a salt bucket. I used 500w of heaters, and just so you know, within 30 minutes the bucket was ice cold. My results were almost dead on with the handy calc on BuckeyeFieldSupply's page.

75 GPD / 50 PSI / 50 degrees = 44 GPD
75 GPD / 80 PSI / 55 degrees = 49 GPD

I ran the numbers a few minutes after the water had been running, and the bucket was pretty hot. So a lousy 5 degrees was all it increased roughly. Most importantly, that was on a warm bucket. After 30 minuets and the bucket is cold, you're wasting 500w with ZERO return.

So let's go overboard and say you have a full 60 minutes of 4 extra GPD at 500w. That's not even worth wasting your time, and is a waste of electricity/money.

Here's something that actually makes sense, get your PSI boosted. At 36 PSI, yes, your RO/DI is struggling bigtime.

Your actual likely output (given the 50 degrees I mentioned earlier and assumption of 75 GPD membrane):
75 GPD / 50 PSI / 50 degrees = 30 GPD
$120 booster pump from BuckeyeFieldSupply:
75 GPD / 80 PSI / 50 degrees = 75 GPD

Yes over double. So waste a TON of watts for ~60 minutes increased production, or buy a pump with minimal draw and have it permanently and properly fixed. Your call


And just so you know (feel free to search/research as well, don't take my word as the spoken truth), I'm stating this becuase I went through the same thing... but mine was 40 PSI instead of 36.

 

[cashyboy]

Wow, nice experiment, I agree dont waste your time, my inlet temp is 50, and I never have a problem, I get roughly what my system is rated at, maybe a little under.

 

[Jandree22]

thanks guys. Eric thanks for all of that analysis from your experience. I will counter that I was going to utilize the fuge with strong circulation and 100g of water volume on it's side as far as absorbing all that cold, but I see your point.

Ultimately, yeah I'm being a cheap bastard... and I was fully expecting at least one person to call me on it For the role they serve, IMO booster pumps are very expensive and I was hoping to get around it (more like $150 after buying separate power suppy?). Using the calculator (thanks for the link), an increase of water temp (if I could get up to 70*F) boosts production by 50%, however yeah an increase in pressure yields a 100%+ increase.

I may still warm up the inlet water some how, but in the end I'll just have to get a booster pump. Just looking for experiences with the original idea... of which you guys helped me out with there. thanks again

 

[RokleM]

Nothing wrong with being cheap You have to question however if you're using that 100g, how much it takes to heat it (reef or otherwise). If it's a reef and it assists in cooling purposes, you're out of luck during the summer when it's really hot.

Yes, the pumps have a little cost to them, but the change in performance can't be ignored.

 

[Jandree22]

idiot question while we're talking booster pumps... do you just plug in the pump when you want to make water, and unplug when you're done?

 

[RokleM]

There are different methods (pressure sensing, etc), but yes that's the quickest/cheapest.