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Terry thanks for your question.  There certainly is a dfference between a solar expansion tank and a regular water expansion tank.  The main difference is in the material that the internal bladder is made from.  Because a solar hot water system can go into stagnation and get very hot the bladder needs to be made from a EPDM rubber membrane.  Our bladders can handle temperatures 130 C or 270 F. as well they are meant for Glycol mixures greater than 50%.   Another key feature of a solar expansion tank is that the tank itself can normally accomodate more volume of expansion compared to a regular water tank.  This is important when a solar system goes into stagnation as it will need to accomodate the expanded volume of steam that can occur.   Dan

Post By : Dan Jung Dated On : 06-25-2013

Thanks for that answer.  I know that a solar system can get very hot.  I also noticed that your solar expansion tanks have a replaceable bladders.  I have a solar heating system that we are installing that uses one of your SunRain 30 tube solar vacuum collectors.  What size of expansion tank would you recommend? T

Post By : Terry Simon Dated On : 06-25-2013

Terry I would recommend the SolarVarem 25 expansion tank (6.6 gallons).   This will be adaquate for one 30 tube solar collector. Dan

Post By : Dan Jung Dated On : 06-25-2013

Terry, We carry two difference brands of solar expanision tanks the size you would require is  25L or 6.6 gal   priced at $130.00 Thanks Alan

Post By : Alan Anderson Dated On : 06-25-2013