Best Of

To be clear on your query, I can not find any specifications on a Viessmann model BK200E anywhere in the old or new equipment catalogs i have access to. I do know that many of the Viessman gas and LP boilers are condensing boilers and do not fall into the Category I venting design that allows for chimney venting.

here are the venting categories:

Category I is characterized by negative pressure and non-condensing appliances. These systems rely on gravity to vent flue gases, and if there is a leak, air from the space will flow into the flue pipe rather than flue gas leaking out. Category I venting systems can use single wall, double wall, B-vent flue pipe, or even a chimney.

Category II is also under negative pressure but may produce excessive condensate. These appliances are typically condensing and have a combustion efficiency greater than 83 percent under ANSI test conditions. However, Category II products are no longer manufactured.

Category III operates with positive pressure and non-condensing appliances. If there is a leak in the venting system, flue gas will flow from the flue pipe into the space, which poses a safety hazard. Therefore, Category III vent pipes must meet additional safety requirements, such as being gas-tight with gas tight venting systems.

Category IV is positive pressure and condensing, typically used for high-efficiency appliances with an annual fuel utilization efficiency (AFUE) of 90 percent or higher. These systems require sealed joints and are often made of materials like PVC or CPVC.

I believe the Viessman boiler you have would fit into Category IV, but I can not be absolutely sure since the model number you posted is either incorrect or is from a time before internet records are available. Absent more information my vote would be the vent according to the manufacturers venting instructions.

EDIT: it appears that Viessmann does make a steam boiler for commercial use. I do not have information on older models, so it is possible that if @heron98105's old Weil McLain is a commercial boiler in the 20 HP range and above,

Then there may be a Viessmann steamer to replace it.  I don't have access to older model numbers but the newer boilers may be one of these:

And this Viessmann may be able to be vented into a chimney after you follow @Jamie Hall's suggestion about inspection. The consensus is still "Follow the manufacturer's venting instructions."

Then the chimney vent is NO

You can use an abandoned chimney as a chase for the recommended vent material. but you can never use that chimney to vent a Cat. I vented appliance as long as the Cat. IV vent pipe is inside that chimney

EDIT:

In this instruction manual for venting Viessmann boilers, on page 83 there are instructions for using a chimney to vent a Cat. IV appliance. Viessmann venting instructions. I hope this answers your question.

Absolutely not...that is a 95% Condensing boiler (very low flue temperature). You can ONLY use the old chimney as a pipe chase, as the other guys stated. I'm using the exact same Viessman model on a project right now, but using PP (polypropylene) venting directly outside through basement wall. Mad Dog