Viessmann Vitola 200 w/ Riello Stack Temp @ 254

shoudabeenaplumba

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%

C02-12.5%

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'Brien

Vitola

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!

shoudabeenaplumba

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'Brien

10 years too long?

Tell me where you can get 10% tax free,risk free? A lot better than my .45% money market account!

meplumber

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.