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Thermostat Setup - Honeywell ProSeries TH411OU2005

Dathanz Member Posts: 34
edited January 2023 in Strictly Steam
Quick question for the group --

Today I looked up the installation instruction manual for my thermostat as I wanted to know more about it specifically to check and see if it is set for steam. I didn't know how to access the ISU before so this manual was definitely helpful.

As I went through the menu, as I suspected, it was not setup for the steam setting. These are the changes I made.

200 -- 3 (was originally set to 1)
205 -- 12 (was originally set to 9)

370 -- 1 (This was already set to 1 so I left it based on the picture from the manual below)

First....I want to confirm that indeed these changes needed to be made.
Second....what difference should I expect (be aware of) to see now that these changes were made?

Something else I haven't been able to find a concrete explanation for is how the temp setting and CPH setting work together. Since I changed it to the steam setting and the CPH setting is set to 1 will the system only run 1 cycle per hour regardless of the house temperature or does the CPH setting only come into play to "maintain" the selected stat temp. Will the system run multiple cycles per hour if the stat is calling for heat to make up a difference.....i.e. house temp at 65 and stat set to 70

1 Pipe Steam System | Upstate NY


  • Jamie Hall
    Jamie Hall Member Posts: 22,973
    The CPH setting is a bit of a misnomer. It doesn't really restrict the system to one start per hour, but what it does do is let the system run longer when called and rest longer between cycles.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Dathanz
    Dathanz Member Posts: 34
    Ok. So other than timing the length of the run cycles from the previous setting compared to now I shouldn't notice anything major in the way the system operates?
    1 Pipe Steam System | Upstate NY