Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Honeywell Digital Tstat settings question

adasilva Member Posts: 144
edited January 2018 in Strictly Steam
Honeywell RTH111 tstat has settings for different types of heating systems. Question is what is the difference between them. I.E Gas/Oil Furnace vs. Gas/Oil Steam or gravity system?


  • Jamie Hall
    Jamie Hall Member Posts: 21,528
    In terms of operation, the differences are in how many cycles per hour the system will try to run. High mass systems such as steam or gravity systems usually work best on fewer, longer cycles, while very low mass systems such as furnaces have to have many short cycles.

    Pick the option that best describes your system.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • adasilva
    adasilva Member Posts: 144
    @Jamie Hall thank you for clarifying that. On cold days my gas boiler runs for about 20 minutes per hour. To be honest when I install the T stat I had no idea about those other settings and I'm wondering if it would run less on the proper setting.
  • BobC
    BobC Member Posts: 5,409
    The first question should be is the house comfortable and does it heat evenly. If you have high mass radiators or cast iron baseboard fewer cycles per hour are needed because all that irn holds the heat well. If it's forced hot air there is zero mass,things cool off very fast and you need many cycles per hour.

    If your trying to cut fuel costs the best bang for the buck is to tighten up the house, if heated air can't escape cold air can't easily find it's way inside. ALso the burner should be adjusted to make sure its running right.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • adasilva
    adasilva Member Posts: 144
    The house is comfortable but I'm sure the envelope could be sealed better as it is old and in New England. I am working on the main vents as well as I recently learned that the ones I have I'm not nearly as efficient as they should be. It's all a learning process