I would set both and yes I like stage 1 at a 2f diff. and stage 2 at a 3F differential

Posted By joe.ami on 15 Aug 2014 07:58 AM
I would set both and yes I like stage 1 at a 2f diff. and stage 2 at a 3F differential

When you say stage 2 at 3F diff, do you mean 2F at stage 1 + 1F at stage 2? Or 2F + 3F?
I did set set both stats to a 2 degree diff for stage 1 last night and I saw one cycle that then ran for 18 minutes. Given cooler temps today, it may not run at all but I was pleased to see that one longer cycle. My installer came by yesterday and they were still insistent that Climatemaster says to leave the diff at 1F.

By 3F diff I mean from set point. So if you set at 72, second stage won't come on until it is 75F.

OP- “I want to be happy with this system and have it be as efficient as possible but I'm struggling with this issue and want some peace of mind before I am done paying the installer and they move on”.
OP- ”I will admit that the house is quite comfortable (something the installer keeps focusing on) yet I can't believe that the cycling like this is normal.”
Response- I understand that you want to be happy and have an efficient system. I respond here because I want the same for you. You have paid good money (if the installer has been paid) and you should expect it, however, I believe you are chasing your own tail with your and others perception of “short cycling” and its effect on efficiency. It would not be prudent to optimize a system based on runtimes at a 33% duty cycle or less (5min on, 10min off) for the following reasons (some that are specific to your installation and should be not be taken as universal)-
-A system should be optimized based on a year round balance of comfort and efficiency. This balance is not the same for everyone. Any changes to a manufacturers default setting should be evaluated based on overall annual system performance and occupant comfort. Your changes now may not serve you well when it is 18f outside this winter.
-The thermostats job is to control the system while maintaining a comfort level of your choice. You shouldn’t be a slave to your thermostat (unless you prefer) ie. The need to reprogram settings as system operating conditions and seasons change. The system is most economical when not running. Introduction of some control schemes to artificially encourage longer runtimes may actually increase total running costs.
-In many heating dominant climates you will usually have to concede that you will be oversized in cooling and thus will have to endure reduced runtimes during low load conditions with water to air equipment (with the notable exception of just recently available modulating equipment).


OP- “I don't want to be replacing my unit sooner than necessary.”
Response- I have established 4CPH is well within Copelands 10 starts per hour max. At 4CPH there is a 2.5x safety factor beyond what should be considered as mechanical short cycling that may affect the lifespan of the equipment. I hope you will find some peace of mind regarding this.


Jonr- “As the study says "Steps should be taken by the designer/installer, to ensure that under all load side operating conditions, the heat pump will run for a minimum time of the order of ~10 minutes." The OP is at 5 min, which is a short cycle from an efficiency standpoint.”
Response - The conclusions in the study are based on a Water to Water system which emphasizes the implementation of a properly sized buffer tank to maintain ~10 min runtime during low load conditions. This is not a design option with Water to Air systems.

I expect that joe.ami's suggestion and/or duct changes will make it a design option.

EvilTwin
After observing your posted myewise monitoring data, I believe you are running mostly in 2nd Stage based on KW power observed. You should be running only 1st stage (Y1) with low load conditions to encourage longer runtimes. and greater comfort.

Can you confirm at the Jackson Zone panel by observing Y2 LED?

There could be numerous reasons for this including-
-Incorrect current sensor locations
-Sensor calibration
-LV wiring
-Tstat setup
-Zone Panel setup and control logic