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Temperature Settings

Energy companies recommend that people lower the temperature in the house at night or during the day for the sake of trying to conserve energy. Downside, especially with a system which short-cycles (every minute), is that it creates a larger hill to climb during the recover periods, vs. keeping the house temp at a constant.

Is there any "winning" approach or does it really depend on the characteristics of each system on which one is better? How would you know which one is best for your system?

In other threads, I believe i've quickly seen thermometers that allow you to "stagger" the recover period. For instance, on my thermostat, I can go from 60 to 68, instead of going from 60 to 62 to 64 to 66 to 68. How is it that this approach assist in saving energy?


  • BobC
    BobC Member Posts: 5,479
    Shallow setback is best.

    High mass systems do not like deep setbacks, it's unlikely you will save money because of all the energy it takes getting everything back up to temperature. Reducing air infiltration and adding insulation are the avenues to pursue.

    If you can recover in steps it might help but I don't think anything over a few degrees will really work well unless you are going to set the temperature back for several days.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • nicholas bonham-carter
    Setbacks or not-that is the question

    Whether its nobler to suffer the clanks and clunks of errant piping, and outrageous fuel prices, and sleepless nights.....

    The energy companies need to study the effects of various schemes of energy conservation methods a bit more on each one of several types of system. I do not think setbacks less than one day in length save anything on a steam system which must heat up the whole thermal mass of the house. The benefit of steam is in its ability to supply comfort at a lower temperature than the forced air system. For steam, 65 degrees can be the new 72 degrees (in the forced air world).

    I have forgotten whether your boiler is atmospheric or wet-base. Can it be down-fired to come closer to the load?

    Can you make the I-pipe radiators into 2- pipe by putting in a small return?--NBC
  • icesailor
    icesailor Member Posts: 7,265

    I guess you have a steamer?

    I'm not a steam pro but I have to ask. Why does your system cycle on and off every minute? Is it cycling on and off on the limit control on the boiler because the pressure drops? Or is the thermostat causing the burner to cycle? If it is the thermostat, the cycle/heat anticipator needs to be set for a longer run/cycle or the thermostat anticipator is burned out. If it is a digital and not a mercury bulb, you need to set the cycle adjustment to one instead of two, three or four. Is the steam pressure setting too high in the system?

    It should not be cycling every minute if it in fact doing what you said.

    Setback thermostats on steam systems are open to discussion. Not so much on wet water systems.
  • Clank Clank
    Clank Clank Member Posts: 30
    Steam system

    Yeah, it goes between 1.5 PSI to .5 and back. Takes about a minute to go between those two pressure points (controlled by a vaportstat) until the thermostat is met.

    Currently plenty of main venting and the thermostat heat cycle is at 1 ...

    That said, system has a set of issues that could cause the short-cycling. (e.g. my oversized boiler (55K needed with 145K supplied by a Weil Mclain EG-50 boiler), and supply lines being only 3/4"). I'm looking into alternate solutions such as time delay switches but have to learn more about options ..

    To properly fix, I'd be looking into what NBC is suggesting and turn the current misaligned one-pipe system with air vents into a properly functioning two pipe ( since i have returns running to many of the radiators already,.. they are just not connected and don't have steam traps installed, etc.).

    In regard to down-firing, I'm guessing The Weil Mclain EG-50 can be but have not looked into it. I've read mixed feelings about going ahead and doing that.
  • Chris_L
    Chris_L Member Posts: 336
    Staggering Setbacks

    I've used the approach you mentioned of staggering the setbacks to prevent cycling for a number of years.   I think the success of this approach really depends on the system.

    In my case, I have a 266 sq ft boiler attached to 165 sq ft of radiation.  It takes about 40 minutes to start cycling, with a cut-out pressure of  just under 2 psi.  I set the thermostat back to 59 at night, and up to 62 in the first morning step.  Takes about 1/2 hour to satisfy the thermostat--no cycling.  The second program is for 64 degrees an hour later.  This eliminates any cycling and reduces the potential for the temperature to overshoot the set point.

    I have a rental unit with an even more over-sized boiler (356 sq foot boiler attached to about 190 sq ft of radiation).  It does a lot of cycling on a 5-6 degree recovery.  I bought a couple thermal fuses and considered putting one in series with the thermostat on the end one of the radiators to give a longer cycle time.  But I but never tried it (being reluctant to tinker with my tenant's system). 

    The fuse would act as a temperature switch that opens at some set temperature (around 180 F I think), and close 20-30 cooler.  If you want to try this on your system, send me a message, and I'll be happy to mail you one of the fuses.  I'd only ask that you post the results here.
  • Clank Clank
    Clank Clank Member Posts: 30
    Good idea ...

    First, thank you for the offer. Truly appreciated. Given the location of everything, issue I would have is running the wires that would go from thermostat connections to a radiator in a discrete enough manner. Thats one of the reasons i was looking into switch that can be wired down in the boiler rm that can be based on a time setting (maybe 10-15 minutes or so). Wouldn't be as smart as the temp switch solution you proposed but would theoretically cut down on some cycles. I have to look into it further.

    thank you again