# [TRNSYS-users] Type 2b problem

Thu May 8 08:37:52 PDT 2014

```Karel,
If you are looking for a simple building thermostat that will take
both a heating and a cooling set point try using Type108 instead of
Type2. Type2 is a differential controller meaning that its control
decisions are based on the difference between two temperatures (like the
temperature of a water tank and the outlet temperature of a collector)
instead of the comparison of a monitored temperature to a setpoint. You
can of course use Type2 as a thermostat but I think Type108 will make
more sense.
Kind regards,
David

On 5/8/2014 08:29, Karel Fore wrote:
>
> Dear TRNSYS-users,
>
> I have a problem in my simulation with a Type 2b Solver0 (succesive substitution) control strategy:
>
> Upper input temperature = variable inside temperature of my building
> Lower input temperature = 0 (not variable)
> Monituring temperature = 60 (not variable)
> input control function = output control function
> Upper dead band dT = 22
> Lower dead band dT = 21
>
> So, when my buildingtemperature starts climbing over 22, the type 2b output =1
> When it falls down lower than 21, output = 0
>
> Problem= when buildingtemperature is dropping and reaches values e.g. 20.95; 20.89; 20.93; 20.99; 20.95
> the solver doesn't give me 1 or 0 but values like 0.93; 0.95;...
>
> Does anyone know how to solve this problem? ( when the building temperature is 20.99, I want the solver to give me the value 0)
>
> Thanks a lot in advance,
>
> Karel
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