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Viessmann Vitola 200 w/ Riello Stack Temp @ 254

I was in a mechanical room the other day drooling over a boiler combo I've comtemplated for my home (If money wasn't a concern).  Viessmann Vitola 200 w/  a Riello F10 burner.  It was a mixed system with both radiant floor and baseboard.  The service folder was there so I started checking it out and noticed on the factory burner test sheet the gas anaylsis was as follows:

T. Air- 74F

T. Gas-254F

O2-  4.1%


I couldn't find any notations from the installer if he'd corrected this, but why would the factory test be set up like this?  In the brochure for the boiler it states a net stack temp of 329 degrees with a water temp of 167.   I know this boiler is supposed to be great at handling ultra-low return temps, but what about stack temps.  Could too low a stack temp harm a boiler with no low limit?

 Is the danger in low stack temp really about protecting the flue liner?


  • Robert O'BrienRobert O'Brien Posts: 3,113Member

    Vitola won't condense in the boiler but the flue is still a problem. Use a  liner or the chamber insert has spots to drill out to increase stack temp if necessary. If you are going for a Vitola.go Vitoflame!
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  • shoudabeenaplumbashoudabeenaplumba Posts: 74Member
    So the weak spot .

    Is the flue?   Depending on the cost to reline I would think it would be cheaper in the long run, just not for me  I only burn about 1000 gallons/yr so I'd be looking at 10+yrs payback to line my chimney instead of losing 3% on the efficiency.  I just can't stand the thought of having to LOSE efficiency. 
  • Robert O'BrienRobert O'Brien Posts: 3,113Member
    10 years too long?

    Tell me where you can get 10% tax free,risk free? A lot better than my .45% money market account!
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  • meplumbermeplumber Posts: 678Member
    Gotta line the chimney

    In some states, the chimeny must be lined on every boiler installation.  I have done a large number of Vitolas and they are the cat's meow.  I try to set my stack temps at around 325.  The boiler can handle return temps down in the 70 deg F range but the chimney can't.

    As mentioned before, there is a place to drill out holes in the back of the stainless steel chamber.

    Good luck.
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