[TRNSYS-users] Type 121b Furnace

Jeff Thornton thornton at tess-inc.com
Mon May 22 10:19:55 PDT 2006

> I am using Type 121b as a preheater for the outdoor air. I combined the heater with a controller (type2) that
> makes sure the air is heated whenever the outdoor air temperature is below 16°C. This controller gives a control function to type 121b. I've put the setpoint of the heater to 16°C.
> (I ignore heat losses), but every time the outdoor temperature is already 16°C before heating up, 
> the heater heats still heats up the air and the temperature becomes > 50 or 60°C. 
> Can someone help me with this?

Without seeing your input file it's impossible to tell you what's happening in your simulation, but you do not need a Type 2 controller if you're using the furnace.  Simply set the setpoint to 16 C, with a large capacity, and leave the control signal set to a constant value of 1.0. The internal controls will keep the outlet at 16 C if the inlet temperature is below 16 C.


Jeff W. Thornton
President - Thermal Energy System Specialists
2916 Marketplace Drive - Suite 104
Madison WI 53719
(608) 274-2577 

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