We have a heating system that uses an ntc resistor to measure water temperature. I would like to replace that ntc resistor by a fixed one (low enough to disable heating) temporary on a 5 minute schedule, or any other.
It's to prevent the warm water using up all the heat and not leaving any for the central heating of the building. We got fooled by the contractor and a proper upgrade would now cost several thousands, so we just want to trick the system. ;p
The arduino is not supposed to measure anything, just to connect one of the two resistors to the heating system.
Is an arduino the right choice for that? If yes, which model? What extra elements would I need? Transistors? Relays? They shouldn't have too much own resistance to not influence the measuring of the heating system when the NTC is connected.
Just a simple connection of the extra resistor would work too because the resulting resistance would be lower and still indicate "water is hot enough" to the heating system.
Any help is welcome, even if it is not arduino based.