Can 100 degree water destroy RO membrane?

[number1gsxxr]

So my dad installed a recirculating pump off of our boiler without my knowledge to keep the hot water warm for our upstairs since it is a long run of pipe. I have a mixing valve installed before my RO/DI unit to keep the water about 77 going into the unit. The other day I went to make a couple gallons of water for top-off and I noticed that the clean water line was overflowing my 5-dal bucket and the waste line was just about to the top of my 5-gal waste bucket. I can usually prioduce a full 5-gals of waste water in 25mins. I thought that this was odd since the clean water bucket was full before the waste bucket. So I used a laser thermometer to see what the temp was since the water was very warm. The 1st stage of my unit was reading 99 degrees F! I think that the recirculating pump that my dad installed is causing too hot of water to reach the unit. My TDS coming out of the RO membrane was reading 15 and it has always read about 2 the last couple of weeks. I was also reading 2 TDS out of my DI chamber and that has always read 0. I think the hot water has ruined the membrane which in turn used up some of the DI resin. Your thoughts?

Cliff notes: Approximately 100 degree water was going into my RO unit. Do you think this has ruined my membranes (I have 2). Used to get 2 TDS out of the membranes now I'm getting 15. All of this literally changed overnight.

 

[Leroy]

At 77 degree your membrane and the filters were fine but at 100 degrees I'd suggest to change them out. They're not made to with stand that temperature. Change membrane and filters also the DI. All kinds of accidents can happen. Once your filters are all set everything will be good to go......cold water only.

 

[number1gsxxr]

Thanks. That's what I figured.

 

[T TOWN REEF]

Check it with a tds meter if the waters good don't bother changing it.

 

[T TOWN REEF]

Sorry scanned to quick i would change it.

 

[number1gsxxr]

Just tested the water after the RO membranes and after my DI chamber. It was reading 3 TDS after the RO membrane and 0 after the DI resin. Interesting. I wonder if the hot water somehow caused the flow restrictor to start acting up. It's strange how I'm back down to 3 TDS after it was reading 15. As long as I keep getting 0 after my DI resin I guess I'll keep using them.

 

[dcforester1]

I know you get better ratios with warmer water, but does anyone else do this(mixing valve)? Just curious I wanted to try to keep my system as efficent as possible.

 

[number1gsxxr]

Actually what I used is an anti-sweat valve typically used on toilets but does the same thing as a mixing valve. Anyways I decided to use it since my RO unit is in my garage which is quite cold typically. If I went off the cold water line alone the water would probably be 50 degrees or colder in the winter months.

Here's a link to the valve I'm using.
http://www.watts.com/pro/_productsFull.asp?catId=64&parCat=273&pid=720&ref=2

 

[dcforester1]

pretty cool, I had never seen one of those

 

[bill120mph]

I didnt realize people did this, I'll have to look into it, How much did the valve change your output?

 

[Jennifer]

That is a pretty cool valve.
I need to get me 2 of those, one for my RO and one for the toilet at my camp. That camp toilet sweets so bad during the summer, the well water comes from an underground mountain stream that is always cold.
i was going to make something myself with 2 valves but that is a much better solution. Thanks for posting it.

 

[jbishop]

I think you would be fine.

 

[Joel A]

where do you guys get your hot water? I know my hot water comes from a hot water tank... and is FULL of sediment and other crap.. measure the TDS of hot water in your house versus cold water... in my case hot water has a significantly higher TDS reading.. enough to make it so that i wouldn't want to run any sort of hot water through my RO unit because it would have to work harder to get it down to "0" and it would exhaust the filters quicker.

 

[Jennifer]

The older the hot water tank is the more sediment you will find in the hot water.
Hot water tanks are suppose to be flushed at least twice a year.



That what the spigot on the bottom of the tank is used for. Hook a garden hose to it and let it run for a while, turn the gas or electric off to it so it is not wasting energy while you do this. Also if your tank is really old and has never been drained or flushed this valve may not like being turned and may not seat properly when you go to shut it off. A simple cap for a garden hose with a oring will stop any drips from it. Do not forget to turn it back on when you are done.

That being said I have never actually measured the TDS of my hot water.

 

[rjdudek]

Membranes are designed to operate at 77. The higher the temp the more water produced BUT the quality will drop. Think of it like the little holes in the membrane expanding when it is warm. More water produced with less waste and more impurities getting through. The membranes should be fine once the temp drops back to normal. The material should not degrade until you go past 110. You had the high TDS from the membrane performance dropping at higher temps. All professional RO units have blend valves at the front end to keep water at 75 to 77. The inverse is also true, cold water will make better quality, but at a serious reduction of product and an increase in waste

 

[number1gsxxr]

Membranes are designed to operate at 77. The higher the temp the more water produced BUT the quality will drop. Think of it like the little holes in the membrane expanding when it is warm. More water produced with less waste and more impurities getting through. The membranes should be fine once the temp drops back to normal. The material should not degrade until you go past 110. You had the high TDS from the membrane performance dropping at higher temps. All professional RO units have blend valves at the front end to keep water at 75 to 77. The inverse is also true, cold water will make better quality, but at a serious reduction of product and an increase in waste

This makes sense and why my TDS is reading low again with the cooler water.

We don't have a hot water heater in our house. We have a boiler that heats water up as it passes through. I'm not sure if has some kind of internal storage tank where sediment can collect however. We do have a whole house sediment filter on the main water line into the house, then that water goes to the other side of the house and over to my RO unit. Luckily we get Hingham water instead of Cohasset water which, IMO, is a lot better. I forget what I was getting for TDS before the RO unit but as I recall it was pretty low to begin with.

 

[bill120mph]

I am going to set mine up soon, I also found an inline thermostat to keep am eye on the temp. Very cool set up!

 

[JPags]

I hook my RO/DI directly to the sink in my basement so I can mix the hot water and cold together when making water. One time when i started making water I was watching the output form my RO and noticed the TDS number was not going down to 1 or 2 which is what I am used to seeing.

When i checked the water was much hotter than normal, so I adjusted the water again and after a few minutes the tds went back to 1-2. I did not leave this running long but I have seen the same thing when running hotter water through the membrane.

I would run the system and check your tds, that will tell you if you need to replace the membrane.

You probably used up a lot more of your DI than you wanted but thats why I have a DI bypass valve and make sure the water is between 1-2 before I send it through the DI and into my bucket. Saves my DI resin.

John