[Greenbuilding] Tankless HW and hard water

[Aaron Lamperti]

Hi All,

I apologize in advance if this question has received lots of time on  
the list in the past.  I tried to scan the archives and didn't find  
anything.

Does anyone have experience/opinion regarding use of tankless hot  
water heaters with hard water.  A quick scan of internet opinions  
turned up a range of concerns (doesn't it always!).

1.  Shouldn't use tankless because lime will block heat exchanger and  
reduce efficiency
2.  Lime won't form since there isn't a point heat source to boil water
3.  Back flush every (insert time range here) with vinegar to remove  
lime
4.  various filter/softener arrangements

Thoughts?

Thanks!

Aaron Lamperti
Norwich, VT