I had a tank heat exchanger pop over the weekend. The tank is only 3 years old, 2 months out of warranty. What a joke. BTH-300A. I sent the factory all the info and they are perplexed. I have another tank right next to it with corrosion in the flue vent elbow. It might be next. These things list at $$$$ and only last 3 years. Lame. Anybody have any issues with these tanks?