Garn hydronic design

[Antman]

Can someone give me feedback about my Garn horizontal flue, please? I'm considering converting it to a vertical flue outside the Garn Barn using a tee but I need to know if I'd also have to use a fresh air intake damper to prevent a thermal draft associated with vertical flues. Or, does the presence of a horizontal flue before the vertical flue prevent a draft?

 

[TCaldwell]

Horizontal to a t clean out outside then vertical is a garn approved method. There is a suggested limit length to the horizontal section from the flue collar on the boiler to the t, should be in the manual. A motorized intake air damper that garn sells and is wired to the new style controller is recommended as the draft through the boiler will strip heat.

 

[TCaldwell]

8ft is the max horizontal per the manual

 

[Antman]

The way I wired mine was by getting an external aquastat that clamped onto the pipe where the water entered the heat exchanger. It was open if temps were above the set point and closed if they were below. On the wiring coming from the thermostat there should be seperate wires to turn on the air handler and the furnace. This aquastat was spliced into the furnace wire so that when the heat was commanded by the thermostat the furnace never recieved the message as long as the water temp was above the set point. It worked great.

Thank you for sharing that experience! I couldn't quite envision exactly what you were describing until after I called Taco tech support and the diagram that was provided suddenly seem to make sense. Is this similar to what you did?