More than likely your heat exchanger is rotted out. Have you been maintaining your Ph? A new exchanger is almost the cost of a new heater..

Thanks for the reply, that's kind of what I was suspecting.

Your comment about my Ph levels is very appropriate, yet frustrating. I had some warranty work done on the heater a couple years ago and the repair guy asked me the same incriminating question. But I'm pretty religious about my chemical levels and spent a lot of time on certain web sites to get smarter about the systems. I've kept the Ph levels as close to 7.4 as I can reasonably get it, and I have to add acid to the water frequently due to the chlorine generator. Sigh. Thanks for the help!

Muddy waters (or others)...just out of curiosity...

I was digging around the web looking at heat exchangers and I came across several Pentair related sites that mentions they sell a "heavy duty" version of the heater that is suitable for salt water pools. That sort of implies to me that the non-HD units are NOT suitable for salt water pools? I do have a salt water pool. Is this a recent development with these heaters, or did I have the wrong one installed originally?

All of Pentairs heaters are good for salt water pools as long as you keep your salt below 5000ppm and your ph in balance. The heavy duty models are made with a Cupro nickel core and they do recommend those if you live in a area with a salty air environment. Also make sure your heater is bonded well, this sometimes will also lead to excessive corrosion with a salt pool.

Rusty

I'm a late-arrival to the Pentair Minimax NT Problem Party. Bought my unit from pool installer who probably sold me obsolete, problematic heater. Just acquired 2008. When did Pentair stop making Minimax NT's ? Unsure if it's a TSI, how would one tell ? In summary, my problem, now, late last season, neighbors can smell the gas smell when unit is firing up, 4 neighbors away. Neighbors have called gas company and 911 on me. Pentair Tech, not pool installer came out, Tech said "All appears to be working correctly. Surprised my unit has lasted so long. (It's only 4 yrs old ???) And, it's time for a new one ! (What ?!?!)" Forums opinion on different Pentair ? Switch to Raypack Rheem ? or Hayward Universal ?

Ahhhhh, my pool is salt not chlorine. Wonder if my ph was also a problem to the dysfunctional Minimax heater ?

I read Raypack's/Rheems are good for use in windy area conditions, also...

Have you smelled gas while the unit is firing? The only time I have ever smelled gas on a heater is when the igniter was bad and a problem with the gas line it's self ....4 yrs is not old for a heater and should not need to be replaced. Call Pentair back and ask for a second company if you do indeed smell gas.

I was told that my heater may have a rust issue and it turns my hot tub orange color and also my pool where the heat goes in??? Any one have this problem ???? Picture to follow