New copper preheater cleaning

[Minnesota Tapper]

Finished making a parallel flow copper preheater. I admittedly used too much flux. I used Oatey h20 95 water soluble tinning flux. Hot water flushing got out alot of gunk initially but doesnt seem to be able to get it all out. I can still smell it. Is there something I can fill up the preheater with and let it soak for a day to lift the flux residue and then flush with water again? Been a couple days since it was soldered if that matters any .thanks for any insight.

[Minnesota Tapper]

Did some googling and found that this flux contains petrolatum. Basically petroleum jelly. Which Google says needs to be cleaned with isopropyl alcohol followed by peroxide. Is it safe to use alcohol? Petroleum jelly does make sense because the residue I get when I wipe my finger inside the inlet pipe I would describe as greasy. Vinegar probably wouldn't work to remove ?

[maple flats]

In that case use some rubbing alcohol to rinse then follow it with some hydrogen peroxide. After that flush it well using good potable water, and if you used medical grade peroxide use lots of water. Then drain it well and put it under your hood. You just made a good step to better boiling efficiency.

[Zucker Lager]

I second Maple Flats on the alcohol / peroxide. I installed lots of potable water lines, industrial locations. Alcohol will cut the flux base and remove it. Then you just need to clean that out with something that will give you safe potable water. Water will clean that alcohol out but not sterilize like the peroxide will. One of our fitters installed a potable water line in an area feeding water fountains................didn't flush the lines out and holy smokes when workers started using the fountains there was heck to pay. that flux smell / taste stayed in the water for weeks. Jay

[Minnesota Tapper]

I'll pick up some rubbing alcohol and peroxide. 2 questions....
1.Is it best to fill the pipes and let alcohol sit in there for a day or 2 before dumping or just a short soak?

2. Do I use straight alcohol or should it be reduced?

Its extremely frustrating not being able to see inside the pipes and get in there with a brush .

[maple flats]

I suggest you cut in 10 to 1, water to alcohol (it is already going to be 70%), fill the pipes and let it set for 20-30 minutes, then do a water rinse, followed by a peroxide wash (that will be 3% if medical grade, cut it 3 water to one H2O2) then put it in to fill the pipes. Let set and if not filled, move the heater around so all surfaces get washed. Let set for 15-20 minutes, dump and then flush it very well with potable water.
You need to realize, these are just my suggestions, not an official method. It is what I did when I made my preheater and it worked very well. If you get food grade 35% peroxide, cut it 100/1 and use the same method as above. In either case it will be about 1% peroxide.

[Minnesota Tapper]

Update. .. .Soaked in alcohol and flushed with alot of very hot water. The alcohol is working much better.when the pipes are cool I cant smell any flux residue. However after running 165° water through it a slight flux smell comes back. Im guessing some flux may of got burned inside. I'll keep soaking and rinsing. When its clean I assume I'll know as I should get zero flux smell hot or cold right?

[1ruralmailman]

one way you could try to rinse it with water flowing through it while in place with steam hitting it,just ru the rinse water coming out into the drain,or a bucket.see if this takes the rest of the crap out of it.

[Mike Van]

Dawn dish soap removes grease better than anything, just an opinion.

[Minnesota Tapper]

Thanks for all the ideas. I've been soaking , rinsing flushing over and over again with alcohol,vinegar,peroxide and it's better but the smell Is still there after the pipes dry out. Figured I'm just being overly cautious and worrying about nothing. Pipes probably have a smell after soldering. Cant say I've ever smelled a pipe after soldering until this project. Mike Van suggested dawn soap. Anything's worth a shot so I soaked it overnight in dawn and what do you know...its actually working. I REALLY have to try to get a whiff of that smell now. It's almost non existant now. One more night of soaking hopefully will do it. I'm a happy camper! For a final test I plan to boil a gallon of water and put it in the heater for a couple minutes then drain into a cup for my wife to smell/ taste. She has much better senses than me. Thanks everyone so much for all the ideas. They all worked to some extent.