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T-Stat CPH
Bergy
Member Posts: 11
Can anyone explain how the CPH work on a thermostat? How does it affect the run times of first, second and third stage heat for a geothermal heat pump with electric strips as third stage?
Thanks
Bergy
Thanks
Bergy
0
Comments
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I have a thread about this already going.
I have made guesses, as have others. So far, no one has supplied an authoritative answer. When it gets colder, I might try to guess it better.
The thread is called "How does a digital thermostat really work inside?"0 -
Quite Simple really
CPH controls the first stage contacts on a multistage t-stat. The common settings are 3 (high mass hydronic or steam) 6 forced air gas, and 9 (heat pump). the thermostat will monitor the internal thermistor this many times in an hour. A "smarter" stat will only cycle the device for a very short period 1.5 - 2 minutes) if there is any drop in temperature at all measured at the thermistor. A "less smart" stat will cycle the device no matter what at whatever CPH setting is in there. this was an "electronic" compensation for the old "mechanical" anticipator settings. Most I have set up have worked pretty well. I almost always used the 3 CPH settings even on forced air gas, because hearing that jet engine of an inducer blower come on every 10 minutes drove me insane.0 -
Another Thread
Here is another thread which winds up going into some detail on the way CPH is implemented.
http://www.heatinghelp.com/forum-thread/128816/VisionPro-Thermostat-Problem
Of particular interest is a link to a Honewell document which goes into some detail about control strategies and thermostat operation.
http://customer.honeywell.com/TechLit/pdf/77-0000s/77-E1100.pdf0
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