Saltwater Pool Heat Exchangers

SpeyFitter

So we have had TERRIBLE Luck with AIC Titanium Pool heat exchangers. The "shell" (pool) tappings are made out of this plastic/resin type material and so they basically have plastic FIP connections we need to screw into (of which in most cases it's the Pool guy who does it, and in most cases they use a CPVC or PVC male adapter so it's plastic to plastic). They are notoriously finicky to work with and we've had warranty replacements on many installations and we are doing the best we can to try and work with them but the just of what I have learned in the duration I've been in this trade is anytime you have to use any threaded connections and you have plastic involved, the likelihood of issues & leaks increases significantly, especially where thermal expansion can take place.

So I did a little research and found a company that sells Cupro nickel heat shell & tube exchangers for Saltwater Pools and they maintain they will work and they have had good luck with them. I never knew you could use Cupro Nickel for saltwater, I thought it might be too corrossive but they have all metal tappings and they're also about 25-40% cheaper than the Titanium versions we've been buying for equivilent BTU loads.

Now having said that, on the flip side in chlorine pools when we use Stainless shell & tube heat exchangers and they've been excellent - again all metal tappings, and we've had no problems.

Any thoughts you have would be much appreciated...

Thanks,

Scott

eluv8

aic

Recently AIC has made several changes to their titanium pool heat exchanger. Which model are you using. This last year they increased the wall thickness of the composite and I have not seen to many problems with splitting since they did that. AIC does have specific instructions on what thread sealant to use and how. They have also gone to a one piece design eliminating that weak seal prone to failure in the shell.



If you haven't seen it yet, AIC also makes a flat plate titanium heat exchanger which may be more your style. I personally am not a big fan of letting any other contractor touch my stuff if I can get away with it. I would make the connection myself mark the fitting and give the pool guys a glue in fitting to deal with that I know was done right.



I have never seen a manufacture with Cupro Nickel in a salt based pool application, whats the warranty in writing say. However I have seen stainless get past the one year warranty in salt chlorinated pools, but not much further. I am interested to see what others have to say on this.

SpeyFitter

Just used the "latest"

The model I had blow on me this past week was as I understand it the most recent "update" to their titanium heat exchanger. It may or may not have had thicker plastic on the end caps, but this time they put a metal ring around the FIP, which in theory should alleviate the issue. They also specified that I use loctite 55 or whatever it's called (sort of like hemp, but bigger strand and not natural but I'm guessing man made), of which I received a roll in the box with the exchanger. They recommended doing 15-17 turns with this stuff on the threads (filling the thread gaps) and to use just this, no dope or teflon. I have no doubts that the loctite will help seal it but the exchanger was split in the plastic resin section.

I have asked via email the supplier what kind of warranty they offer on their cupro nickel heat exchanger for saltwater applications. It will be interesting to see what they say that way.

eluv8

15-17 turns

Wow, it has been a while since I read the instructions and do not have a current copy. However 15-17 turns seems awfully excessive. If you are filling in the threads then it would make sense to me that the plastic would be placed under extreme pressure. A metal housing can effectively scrape off the excess sealant as the fitting is screwed in place, and is more forgiving. However the plastic fitting is probably flexing and eventually fracturing under the stress of loaded threads.  I typically only use if I remember right no more than 3 - 5 turns depending on the fitting used, they seem to vary by manufacture and type. You should have just enough sealant on the thread to be able to turn the fitting a couple of times by hand before it snugs up. Then finalize the last turn or two with the wrench, without fully bottoming the thread. If it bottoms I would undo the joint and add the necessary extra wraps of sealant and try again. You do not have to muscle the fittings together, snug is good. I forgot to tighten one with the wrench and it held hand tight, that thread sealant is very good at doing its job.  I use the same method when installing PVC threaded connections.

SpeyFitter

Not per thread

I'm doing 15-17 turns and using that to fill up about 1/2 of the threads (about 5-6 "valleys"), so it's not that bad. It's Loctite, not teflon. When I use teflon it's 3 wraps.

Henry

Salt

We have had excellent experiences with the titanium heat exchangers. We use liquid teflon on the threads with no leakages or breaks. We use normaly the 400,000 BTU model. As for s/s plate exchangers, even a marine grade flateplate type failed after 2 years. It is very important that all metal parts in contact with the salt water be grounded. There is a serious problem with the high head loss of a flate plate type also. Depending how far the exchanger is from the pool pump, there may be too high a pressure drop (normaly it is around 10 PSI). This will then reduce the flow rate through the filter and pool.



I would NEVER use a Cu/Ni on salt or any pool. Cu/Ni is recommended as a better coil in gas fired pool heaters. The pool heater still must be isolated from the pool water if there are any shock chemical treatments.

SpeyFitter

What model?

Henry,

And you are using models with plastic FIP tappings for your Titaniums?

Are the ones you are using AIC's or a different manufacturer?



thanks,

Scott

Unknown

Heat Exchangers

I'm just a home owner but have had a lot of experience with marine heat exchangers. Do you use zinc sacrificial anodes in these heat exchangers? These are a "must" if using a heat exchange in sea water so I would think it would apply here also. They should be checked at regular intervals as the degree of electrolysis /galvanic corrosion can vary a lot  between each individual installation and they should be renewed annually. Without them you heat exchanger will deteriorate rapidly. Just a thought.

- Rod

Henry

Pool heat exchangers

We use the new AIC T400. They recommend the T series for salt water, salt/chlorine and high cholrine pools. S/S in 316L is for fresh water,standard chlorine, We are installing one right now and I have ordered another for another client.

BTW, the first one is installed in a geothermal system/Knight, radiant floor/indirect water heater system that has a total of 15 pumps! I will take some pictures Monday, before the insulation is applied.



Regards,

Henry