Thermostat replacement

mattmia2

in theory but how the algorithm is implemented in the thermostat is usually a bit of a mystery. just think of it as a lower number means longer and less frequent cycles and a higher number means shorter and more frequent cycles. just pick based on system type and see how it behaves over a few days or weeks, probably err on the low side when guessing because you will notice being cold, you won't notice it starting back up just after it ended a cycle as much.

the thermostat uses the cph setting to decide how much of a temp swing to allow between on and off and possibly adjusts the swing based on run time and rate of change in temp. it isn't a linear thing where it just uses a cutin and cutout temp.

in purely electromechanical thermostats the heat anticipator was a little resistor on the temp sensing element that heated the temp sensing element so the longer it ran the more it would heat the element. if the room temp was close to the setpoint the heating effect of that resistor would have a big effect on causing the thermostat to shut off, if it were say recovering from a setback the heating effect on the element from that resistor would be a lot less. the algorithm in the thermostat simulates that effect and the chp number influences how much that algorithm effects shutting off the thermostat before it reaches setpoint.

does anyone know what happened to @BillW@honeywell ?

geemalar

@mattmia2…………thank you for that explanation. So far so good, the system is running significantly longer during each cycle. I really wish I had noticed this earlier, but I didn’t know until I read some of the beneficial information on this website. Even better, during each longer cycle, my 0-5 gauge hasn’t recorded any pressure readings. Then again, it’s started to warm up around here, so it may be a while before I can fine tune it overall. For now I’m extremely pleased with the outcome.