honeywell thermostat th8110 "intelligence"

conversiontime

I replaced a defective rite temp swing thermostat with the model above which I knew was not a swing therm but seemed recommended for steam. The new 8110 is set to 1 CPH, heat only and has been running a week without issue but as I adjust to its algorithm, I am now wondering if 2+- swing works better on my 161k btu steam rating boiler. Very casual observation show the boiler cycles more frequently but runs less time on this new therm. Based on previous years, a 40 minute run time on this boiler seems to be its sweet  point when all rads are very hot but pressure is still less than 1/2 psi. The swing therm ran less often but its cycles often were 45+-. The th8110 runs more like 20 minute cycles but every hour. "Fuzzy math" indicates the new therm is running the boiler approx 30-60 minutes more/day than the old therm.



I am curious if turning off the intelligent capacity does jack to the CPH algorithm. I suspect turning it off does not affect the algorithm, but does disable the recovery or sensing behavior I have witnessed. So maybe I am being too harsh as I have only run the new therm for a week, but overall I miss swing more than I ever figured. Anybody else find the 1+- degree swing on honeywells to be less efficient for larger steam systems?

nicholas bonham-carter

Thermostat intelligence

I think the intelligence of the stat is limited to determining the start of boiler firing to have the recovered temperature (after a setback) be attained by the selected time.

As many of us here feel that setbacks may not save much if any money, the intelligent recovery is not needed.

If your house has high heat loss, with excessive air infiltration, with an oversized badly vented boiler, then setbacks may be more economical.

What really saves money is proper maintenance, low pressure with lots of main (not rad) venting.then you can maintain a constant temperature. Tightening up the building envelop will also save fuel.--NBC