HONEYWELL THERMOSTAT FOLLOW-UP

norb

i have a Honeywell , i believe, rth4100d----after reading a recent post here on the Wall, i checked mine ( I had recently had a new WeilMclain boiler installed and they also installed this thermostat). Upon checking the mode it was in---it turned out it was set at 5 ( the default mode "for boilers with an efficiency below 90%)---this must be a catch-all mode------I changed it to the Number 1 setting for steam gravity systems per the instructions and per this heating help forum. The heat seems to be even better , getting to all the rooms very well. What exactly is going on here with the cycling of the boiler with a setting of 1 versus the default setting of 5? or is the heat better due to the very cold weather we are now having ( causing the boiler to run more) ?

Fred

The setting of 1 means the boiler will run 1 cycle every hour. That cycle will be long enough to heat all the Mains, the radiator runs and the radiators more evenly. The boiler may run anywhere from 10 to 20 minutes and use the hot radiators to continue to heat the romms for the remainder of that hour but allow the mains and rads to cool down enough to allow the vents to all open and be ready for the next heating cycle.
A setting of 5 means 5 cycles per hour, twelve minute cycles, usually 6 minutes on, 6 minutes off. Just not enough time to really heat the mains, runs and rads like they need to be for effecient operation. That 5 setting is designed for forced air furnaces. Enjoy!

norb

thanks again---another question: i am curious, years ago, I had one of those older honeywells that many homes still have. the kind with the dial. How would this model "know" to run a steam system for 10-20 minutes ( one cycle per hour) ? or are they operating the boiler in a diff way ?----just wondering

Fred

Those older ones (and even the new non digital ones) have a "heat Anticipator" that you have to adjust to get them to operate properly depending on the type of heating system they are used with.

SWEI

The old T87 had a heat anticipator in it. The net result was the same, but it was adjusted based on current flow through the stat circuit when the contacts were open.

norb

thanks for the answers

Dave_154

The 5 setting is if you only want to heat your basement..... Don't ask me how I know.

norb

i have a another question regarding the Honeywell rth4100d thermostat. My original question, some time ago, had to do with the setting of #1 for steam heat systems. The answer was that this setting causes the furnace to cycle one time per hour.
My new Questions is: What if the thermostat is set to , say , 74 degrees. If the room ( thermostat) is maintaining 74 degrees, will the furnace still kick on in roughly one hour? the room where the thermostat is, my living room, seems to be maintaining 74 and the furnace is only going on about once every TWO hours----thus my upstairs bedrooms are cooler than normal. I did change out the living room valve to make that room warmer, and so I will mostly likely go back to the valve I had---a Gorton #4. However, if you still could answer my new question: Should the furnace kick-on roughly each hour at the mode setting of #1 or only of the temp drops below 74? Also, is it possible that I knocked out the setting of #1 somehow when I was programming it for Daylite Savings Time, maybe I accidentaly did something ?