rodi sweating

joekidwell

joekidwell

New member
My rodi sweats like crazy, all the canisters and all the lines....After filling a 5 gallon bucket it looks like I spilled a gallon under my sink. Any way to solve this problem....was thinking about putting a fan under there. Anything else I could try?
 
fairly normal.. or its leaking :)
ventilation will help greatly. .
same reason windows fog up/sweat in the winter,etc... temperature difference/dew point..blah blah blah
 
I gotta wonder if you have a leak. But you say all the canisters and all the lines.

How cold is your water? In TN I can't image your wellhead temp is much less than 58deg. Very cold water sweat more.

I run a 75GPD with a temp of 48 but no sweating. You sure there is not a leak?
 
if its not leaking I would go to local hardware store and get some water line insulation. (might be called something else) but it is made out of a foam and has a slit in it...you just slide it over your tubing and it should help...that is what I did to mine
 
Must be comming from pretty deep under ground to be that cold in TN. I've never had that issue on my RO unit here (it's also in my basement so I may just never have seen it, LOL), but my copper supply lines sweat like crazy if I run a load of laundry.

If you have space somewhere (possibly remotely if it doesn't fit under the sink) get a 5 gallon bucket fill it with water and put a coil of 100' or so of tubing in the bucket full of water, this is usually enough. If this still sweats you could use a small aquarium heater to maintain the bucket at a little above room temp. This actually will improve the function of your RO/DI unit as well as they work better with room temp water.

I've seen people use flow thru aquarium heaters activated by a flow switch also but that's alot more work and cost, but would save on space.
 
look at the package, Probably too hot to put on PE tubing which has a max operating temp of 120 degrees.

If you have a power plug under there just use 25' or so of tubing wraped around the inside of a gallon jug full of water, preferably glass (like a large mason jar or whatever you find) and use a small 25 or 50 watt aquarium heater in the center. (just don't let the heater touch the PE tubing.) plastic container would work also just keep the heater in the center and not touching any plastic.

Adjust the heater temp upwards slowly until you reach a point where you no longer get sweating pipes when the RO runs.
 
zachts said:
Must be comming from pretty deep under ground to be that cold in TN. I've never had that issue on my RO unit here (it's also in my basement so I may just never have seen it, LOL), but my copper supply lines sweat like crazy if I run a load of laundry.

If you have space somewhere (possibly remotely if it doesn't fit under the sink) get a 5 gallon bucket fill it with water and put a coil of 100' or so of tubing in the bucket full of water, this is usually enough. If this still sweats you could use a small aquarium heater to maintain the bucket at a little above room temp. This actually will improve the function of your RO/DI unit as well as they work better with room temp water.

I've seen people use flow thru aquarium heaters activated by a flow switch also but that's alot more work and cost, but would save on space.
Click to expand...

Actually I think it might be shallow, we don't have to worry about freezing here too much. The past few weeks we have had usually cold weather.
 
joekidwell said:
Actually I think it might be shallow, we don't have to worry about freezing here too much. The past few weeks we have had usually cold weather.
Click to expand...

That's what I would have guessed, our lines here are less than 30" deep and get darn cold in the winter. But it only sweats here in the summer when humidity is over 90 percent. (in the heat of summer I can take a cold shower and it's quite comfortable LOL!) It's pretty dry here in the winter months, at least in my house with several dehumidifiers going to keep up with evap from my tanks so the windows don't sweat and puddle on the floor, :lolspin:
 
joekidwell said:
This seems interesting. http:// http://www.petmountain.com/product/reptile-heat-cables/11442-504969/zoo-med-zoo-med-repti-heat-cable.html?utm_source=googleproductads&utm_medium=cpc&utm_term={keyword}&gclid=CNPmpIqb17wCFYEDOgodZQsAAw
Click to expand...

Might work. Never seen it tried, and I'd be worried it would get too hot, unless you only plug it in when running the RO.

volume of water and coil of tubing is a much safer, and cheaper option. tubing is only like $6 for a 25' coil, and you probably have the heater already laying around somewhere.....might not even need the heater as a volume of water will hold a lot of residual heat and minimize the temp differential and sweating.

The heater you could leave plugged in and it would only run when the RO drops the water temp in the bucket, which is a tried and true method.
 
zachts said:
If you have a power plug under there just use 25' or so of tubing wraped around the inside of a gallon jug full of water, preferably glass (like a large mason jar or whatever you find) and use a small 25 or 50 watt aquarium heater in the center...
Click to expand...

Just looking at order of magnitude... assuming a 75 GPD unit with a 3:1 rejection ratio (call it 12.5 gpm demand), a 5-degree supply temperature rise would require 9,000 watts of power.

A 50 watt heater would raise the temperature of the 12.5 gpm supply flow by only 0.03 degrees, and that's assuming complete heat transfer from the heater to the incoming water.

Watts = (500 * gpm * delta-T) / 3.41
 
Clamagore said:
Just looking at order of magnitude... assuming a 75 GPD unit with a 3:1 rejection ratio (call it 12.5 gpm demand), a 5-degree supply temperature rise would require 9,000 watts of power.

A 50 watt heater would raise the temperature of the 12.5 gpm supply flow by only 0.03 degrees, and that's assuming complete heat transfer from the heater to the incoming water.

Watts = (500 * gpm * delta-T) / 3.41
Click to expand...

Uh, Your math seems a bit fishy, I think you misplaced some decimals, a 75 gallon per DAY unit with 3:1 rejection only draws about 0.2 gallons per MINUTE from the supply..........
and you forgot to account for the heat stored in the volume of water and transferred to the incoming water via a long coil of poly tubing in the water. The water being kept at a constant temperature, somewhere between ambient and lets say 90 degrees whatever ends up being needed.

My math says a 150 watt heater would be able to keep up not even counting for the bucket of water and coil of tubing being kept above room temp.

This method has been done before many times and does work.
 
Seems like a small fan would do the trick, and be the easiest. For that much sweating it must be pretty humid under the sink.
 
zachts said:
Uh, Your math seems a bit fishy, I think you misplaced some decimals, a 75 gallon per DAY unit with 3:1 rejection only draws about 0.2 gallons per MINUTE from the supply..........
Click to expand...

Good choice of "fishy." You're right. Apparently I had a brain fart because I didn't convert gallons per hour to gallons per minute. Talk about a mistake I should have caught. That means my results are off my a factor of 60!

Anyway... in the first case, a 5 degree rise would only require 150 watts of heat. And in the 50 watt example, the temperature rise would be 1.6 degrees. That's looks a lot better.... I can see that approach working depending on the dewpoint.
 
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