Good 2 Coil Indirect with Solar Input? Triangle Tube Smart SME?

LB

Hello-



Looking at a Triangle Tube Prestige High Efficiency boiler radiant floor system with indirect hot water.  I looked at the Smart - but have decided to do solar thermal - so the Triangle Tube Smart SME with another coil in the bottom seems like a good fit.  It's a new product so I'm a little bit wary.  It's a stainless domestic tank within a carbon steel outer tank holding boiler water.  at the bottom of the outer tank is a carbon steel coil to preheat the boiler water and domestic with solar geothermal heat.



<a href="http://www.triangletube.com/documents/23/SME_Literature.pdf">http://www.triangletube.com/documents/23/SME_Literature.pdf</a>



Are there other 2-exchanger indirect tanks that you guys recommend for quality, simplicity and longevity?



Heat Flo

Oventrop



Is it worth it to go stainless?



Any thoughts are appreciated.

hot_rod

in your area

find out which has a better lifespan. In some areas stainless works best, in others enamaled steel tanks works better and lasts longer.



Is double walled HX a requirement? I hope not as that limits the choices.



For solar a coil with a lot of surface area works best as supply temperatures are much lower than a boiler supplied coil.



Solar starts when the collector is @ 10 degrees warmer than the tank temperature and should run a tight delta t, under 10F across the collector.



Hard water? I like smooth coil tanks or tank in tank for hard water. Although softening the water will help HX surfaces regardless of the coil style.



If enamaled steel is the final answer look for a large diameter coil and a long coil length. There are a bunch of different brands on the market. Buderus, HTP, Bradford White, Bock, are a few off the top of my head. I'm partial to the Caleffi brand



hr