70 plate brazed water-to-water heat exchanger, 316 Stainless Steel. For use with outdoor wood boilers, hot water recirculation systems, snow melt, solar systems, and many other applications. Our large style 70 plate is 5" wide and 12" long! Don't be fooled by smaller units! These are heavy built quality units, NOT the cheaper 304 Stainless Steel! Maximum pressure 435. Minimum operating temperature -265° F, Maximum temperature 392° F. The feed and return is 1 ¼ " MPT. How to buy a brazed plate heat exchanger: 1. Length and Width. Sizing is not just about the amount of plates, but also the area for heat transfer! Ours are 12 inches long. 2. Port sizing. Most furnaces use 1" tubing, so make sure you are not buying 3/4" ports, as this will decrease water flow! Ours are 1 ¼ inch! They can be reduced down to fit your 1” tubing. 3. Proper sizing. If there is any question, ALWAYS buy the next size larger. It is always better to have more heat, than not enough! Here is a guide to help you: A. 10 plates are used for domestic hot water or small in-floor heating applications of less than 1100 sq ft. B. 20 Plates are used for smaller homes from 1100 - 2500 sq ft. C. 40 Plates are used for larger homes from 2500 - 4500 sq. ft. D. 70 Plates are used for areas 5000 - 7000 sq ft. The photo is not the exact unit, but shown at a different size so you can get the idea of what you are getting. If you have questions, please contact us and let our knowledgeable staff help you get your project done right. No need to shop around, buy here with confidence!