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Is there fuel savings with deep setback with steam heat?

I try to lower thermostat at night and when everyone not home during the day to 63 degrees and increase during morning rush and evenings. Is the fuel savings worth the deep setback if I can avoid shortcycling off from pressure
limiting vaporstat?
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Comments

  • rrwitherspoon
    rrwitherspoon Member Posts: 104
    My system only shuts down via vaporstat from deep set backs otherwise turns off via thermostat. Deep meaning 5 degrees
    ie from 68 to 63
  • Captain Who
    Captain Who Member Posts: 452
    Hmmph. I actually just gave you the numbers I have been getting recently on my own system. Of course, it's been a bit on the warm side here in NJ lately (for winter)
  • Captain Who
    Captain Who Member Posts: 452

    If that's truly the situation, I do believe you're spending a fortune to get steam to the radiators. You save a massive amount of fuel by running one cycle (during recovery) instead of nine cycles.

    You lost me there Hatterasguy. I'm not running nine cycles during recovery. It fires the whole time up until the vents start to close around 35m or so, then it cycles on the pressuretroll until the tstat is satisfied. The timing of it varies of course depending upon the outdoor temp and wind conditions. My system is not optimized yet. I'm waiting for my hourmeter and counter to arrive before I make any major changes. Still on backorder (aargh !).

    I think we're overcomplicating this thing. The numbers don't lie.

    tchack
  • Captain Who
    Captain Who Member Posts: 452
    Actually the way my White Rodgers has been operating, there would've been a lot more than 9 cycles in that 9-1/3 hour setback period. But that's really made irrelevant by the way I'm simplifying that with the concept of the duty cycle. At 20% duty cycle (not an actual setting I made, just what has been occurring recently by my observations), it would've been on .20 x 9-1/3 hours. It probably would've cycled more like 30 times, but I don't know exactly.
  • Captain Who
    Captain Who Member Posts: 452
    FYI I have the tstat set at 61 F, with setback to 53 F. Since the tstat anticipates , it is working out to be a setback time of around 9-1/3 hours, even though I have set it for 9-3/4 hours.
  • Captain Who
    Captain Who Member Posts: 452
    I tend to look at it in a more thermodynamics sort of way in which for the most part, the only losses are up the flue and through the walls of the boiler room, which in my case is slight since it is underground in my basement.
  • Captain Who
    Captain Who Member Posts: 452
    I also use two ceiling fans, set to blow upward on the slowest speed setting. Those don't get turned on until I am downstairs to do it myself and not until the tstat is close to shutting down on recovery.
  • Captain Who
    Captain Who Member Posts: 452
    @ Hatterasguy - Why is 1 cycle per hour the magic number? My tstat doesn't allow that to be set. There is only two anticipator settings: 0.6 F and 1.2 F. I currently have it on 0.6 F, but I am going to try the 1.2 F and think that might be best, but we'll see.
  • Captain Who
    Captain Who Member Posts: 452

    Every single start of the boiler costs fuel.


    I BELIEVE that is probably true. The question is....how much? If I read my gas meter after 5 runs of my burners of exactly 12 mins duration vs the meter reading after 1 hour of a single run, what would the % difference be?

    I have noticed that there is a very slight smell of gas for an instant when the burner first fires, but it is extremely slight and fleeting.
  • Captain Who
    Captain Who Member Posts: 452
    OK but on a thermodynamics basis, that heat is not lost to the system, because it is inside the system piping, which is insulated, and the boiler is also insulated and is located in the boiler room which is underneath the heated space. Most boiler rooms are in basements which are below ground, so the losses through the basement walls are not great.

    I believe that the heat lost up the flue is the only loss that is really significant, so anything that increases flue losses with respect to heat gained to the heated space is what we should worry about. The question would therefore be.......do shorter cycles vs longer cycles with the same overall duty cycle increase the flue losses? That's assuming that the amount of gas wasted on startup due to a few microseconds of incomplete combustion is insignificant.
  • PMJ
    PMJ Member Posts: 1,148

    PMJ said:


    Steam systems really don't do a good job of raising the temperature quickly. So large setbacks in a 24 hour schedule are not a good idea. Small ones, however, can be very useful.

    The data that the Captain shows tends to discount the above statement.


    I saw the numbers. I don't believe any steam system that has been off 9 hours will raise the whole structure it was designed for 8 degrees in one 45 minute burn.

    1926 1000EDR Mouat 2 pipe vapor system,1957 Bryant Boiler 463,000 BTU input, Natural vacuum operation with single solenoid vent, Custom PLC control
  • rrwitherspoon
    rrwitherspoon Member Posts: 104
    Good topic I see I thank everyone for their opinions I will move the thermostat more conservatively from now on
  • Captain Who
    Captain Who Member Posts: 452
    That is my recent numbers PMJ. It depends greatly upon the outside weather conditions. Even though the setback is 8 degrees, that doesn't mean that it always makes it that low. My setback temp is 53 F, but this morning when I came down to do some work on one of the radiators before the system started up, the tstat was still showing 58 F. Everything DEPENDS.
  • Captain Who
    Captain Who Member Posts: 452
    Another factor which I didn't mention is that the average temp during the on program period was around 41 F, but the average temp during the setback period was higher at around 45 F. That is definitely not typical and is due to a warm rainy weather pattern that moved in overnight. So, the boiler would not have had to run a 20% duty cycle if I had no setback period. Maybe it would've been more like a 41/45 x 20 = 18%. Still saved a significant amount of fuel however.
  • Captain Who
    Captain Who Member Posts: 452
    PS: This screwy tstat tends to do 3 tentative short cycles of around 3 or 4 mins before the tstat is satisfied. Then it will be off for however much time it deems necessary before starting the next series of short cycles (could easily be an hour or more). I realize that may not be exactly ideal. It is obsessed with not overshooting I guess. 1.2 F anticipator setting should be much better for steam than the 0.6F setting I currently have it on.
  • Captain Who
    Captain Who Member Posts: 452
    To determine if my boiler system is wasting fuel you'd have to know what the heat loss of the building is, the btu input to the boiler, the surface area of the building, the cu ft. of interior space, etc. etc.. Now we are over simplifying things lol.
  • Captain Who
    Captain Who Member Posts: 452
    Who said anything about "reduced heat loss from the building"? It's really simple. If the burner is off long enough vs maintaining the setpoint temperature, the fuel expenditure to recover the setpoint temperature is MORE THAN MADE UP FOR by the savings in not maintaining the setpoint temperature. There IS a breakeven point, as far as the setback duration. That's what my simple equation proved. You even said yourself that you think there is a savings in increasing the cycle time to 2 hours and you described it as a 2 hour setback. Well take that out to a much longer time period and the savings is even greater. I really don't get what the confusion is.
  • rrwitherspoon
    rrwitherspoon Member Posts: 104
    I wonder what Dan Holohan thinks?
  • SWEI
    SWEI Member Posts: 7,356
    Slightly off-topic, but with temperature-modulated hot water heat it is even tougher. We implement optimal start algorithms in DDC to manage both the pre-start time and also the supply water temp based on depth of setback, outdoor air temp, and even the time required for the past several recoveries. It's a hairy multivariable set of equations that always boils down to trial and error. In high mass, radiant-heated buildings, we find that even a 5 degree setback is not really worth doing unless the unoccupied period is at least 24-48 hours.
  • Mark N
    Mark N Member Posts: 1,094
    edited December 2014
    I've lived with steam heat for 25 years. I was advised by father to leave the thermostat at 1 setting and leave it alone. It is set to 70 all heating season. I converted to natural gas 6 years ago and have been tracking my gas usage for heating ever since. I track by the month(they read my meter in the middle of the calendar month) and by the year.

    2009- 531.443 therms, $1.498/therm, $796.10
    2010- 625.933 therms, $1.327/therm, $830.61
    2011- 712.797 therms, $1.185/therm, $844.66
    2012- 587.118 therms, $1.095/therm, $642.89
    2013- 711.444 therms, $1.004/therm, $715.29
    2014- 785.356 therms, $0.853/therm, $699.90

    My boiler is a Burnham IN-4 connected to 260 sq ft EDR. Also, this house is located in Central New Jersey.
  • archibald tuttle
    archibald tuttle Member Posts: 839
    I'm totally onboard with this type of approach but could the setup you describe be 'right' if you don't make 6 oz. on full fire. i guess if all the rads get hot and you use a heat anticipator of some sort (i.e. build lead times into your setback) I would imagine it is slow to first steam. . .

    but the problem for regulating short cycling and fire is the same as the problem for regulating steam period -- nobody has made a decent vaporstat in a decade . . .

    . . . eer, what about this.

    http://www.dwyer-inst.com/Product/Pressure/DifferentialPressure/Gage-Switches-Digital/SeriesDH3/ModelChart

    i'm ready to jump and try it out although they don't rate it for steam temps/conditions, i'm thinking maybe two siphons. (belts and suspenders). It could be $300 mistake, but that is what you have to pay for a real mercury vaportrol is you can still find one. so would i be willing to risk this once to try? go ahead, keep egging me on, i'll try it, i'm warning you . . .
  • archibald tuttle
    archibald tuttle Member Posts: 839

    Folks -- there really are too many variables, most of which can't be measured, never mind controlled. . . . What we have found, with no argument, is that the damage and required maintenance to the structure (particularly plaster, but also old wood floors) and the contents (particularly the three Steinway grand pianos, but also the library and some types of furniture) costs far more than any savings we could hope to make on fuel.

    Assume you say this from some emperical experience in keeping up appearances (and auditory qualities) and not just on the assumption that regular 10 or 15 degree temperature swings cause might cause the kind of damage you report. It is a point well taken for those curating the type of experience you point out. But I haven't had so much trouble with plaster on a relative basis in houses where we use setbacks at the low end of that range.

    As to all the other variables, it seems to me what is still lacking are relatively simple and affordable loggers. As it is, digital and relational temperature control is still in the 19th century from what i can see. i got my last several digital controls self built by nerds on the net. (I hope that that is understood as an endearing reference by the way. I have undieing respect for htose who can't find what they want at a price they are willing to pay and so make it themselves.) e.g. :smile:http://www.ebay.com/itm/SBE-Solar-Tech-Digital-Differential-Thermostat-w-Pwr-Supply-Solid-State-Relay-/291142804500?pt=LH_DefaultDomain_0&hash=item43c976a414

    So I keep waiting for somebody to make a decent accessible logger where i don't have to buy someone's softward and nonsense and where the culture of the company is not cult like. i just was something simple that has a enough channels so i could record sun, wind, wind direction, outdoor temp, firing hours (and setting where modified fire is available), pressure, boiler water temp. although the predominately important variable would just be an hour meter for single fire boiler.

    when you have a lot of information you need an inexpensive practical way to get a handle on it.

    brian

  • archibald tuttle
    archibald tuttle Member Posts: 839
    Actually i was thinking of the 25". I'm not retentive over keeping it as close to zero as possible although in order to cut short cycling what i find useful is accurate control cut out in the 10 to 12 oz range and cut in at 1 or 2 oz. For boilers without modified fire, i've been running a regimen like this although even on the mercury controls the pick-up, i.e. the subtractive differential is touchy. If i'm not careful i can get a circumstance where the control never picks up. With the physical threshold switches that replaced the mercury this is even worse. i'm kind of hoping these controls I linked to could handle the temps with a couple of siphons to protect my investment.

    in addition to giving switching they also have the typical output for logging devices as well.

    brian
  • jumper
    jumper Member Posts: 1,756
    Best answer is it depends.If radiation is sized to warm up your space in thirty minutes,you may want to setback all the way to off.Quebec ski lodges were operated like that.Very early in the morning and in the late afternoon the one pipe radiators whistled and it got toasty fast.The rest of the time skiers skied,slept,were in the dining room,or sucked up being chilly inside.Or they wore their ski clothes inside.
  • ChrisJ
    ChrisJ Member Posts: 12,131
    I like a setback and in my experience even before the EcoSteam it saved me money doing a 3 degree setback at night.

    If your system builds pressure easily and cycles multiple times during a recovery I'd avoid it.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • archibald tuttle
    archibald tuttle Member Posts: 839
    MarkS said:

    Brian, I have something you might want to try since you're willing to experiment. It's off-topic for this thread so I'll start a new one.

    that never stopped me before. Should just change my moniker to jack so everyone can say hi jack after every one of my posts.

    speaking of which, i just got one of those 'personal' notes from Dan Holohan telling me that someone had accepted my answer (which i of course find highly suspect). Anyway, it cited a comment on this thread by number. But i don't see where to find the numbers and the link just takes me to a page without highlighting a post. does anyone know where you find the comment number?
  • archibald tuttle
    archibald tuttle Member Posts: 839
    PS - MarkS points those of us interested in vaportrol substitutes to this new thread:

    http://forum.heatinghelp.com/discussion/152838/idea-for-a-vaporstat-alternative
  • archibald tuttle
    archibald tuttle Member Posts: 839
    actually this link took me to the second page of the thread but i can see from the link itself that it targets a specific comment.

    e.g. http://forum.heatinghelp.com/discussion/comment/1357564#Comment_1357564



    i just have no idea where to right click on a comment to find its number so i have no idea which 'answer' rwitherspoon was 'accepting'. that is actually a useful function that is easy to find on some forums so you can direct folks to a specific comment in a long thread -- whether or not it is accepted as an answer.

    and i did scare quote 'personal' on purpose. i know those notes are computer generated. just tweaking Dan and co. have to tweak since i don't twit.

    brian
  • Captain Who
    Captain Who Member Posts: 452
    edited February 2015
    I still haven't installed my hourmeter and counter yet. I hope to do that this week when I get some flag style spade connectors. Anyway, I have been doing some "data logging" for the past 2 weeks (1/19 to date) using the gas meter and I am certain that in my system I have around a 20%+ savings during the setback+recovery period over the alternative of not having any setback. I have a 8deg setback which is programmed to begin at 10pm and end at 7:45am. I have been using weatherunderground.com downloaded data from a weather station 2.3mi away from me and have been calculating the avg wind chill temps and avg degree hours from this data. It also has solar radiation data but I haven't yet determined how to incorporate this data but it clearly has the effect of making the data skewed conservatively towards even more savings, if I knew how much to mathematically weigh it into the calculation. I excluded days where I did my washing (both clothes and myself!) since I have gas water heater and dryer. When I cooked I compensated for the minimal effect of the gas used by the range and oven. I also counted the followup thermostat cycle after the recovery one completed as part of the recovery period because it takes a little while for the walls and furniture to come back up to temperature, even though the ceiling is at above normal temps after the first time thermostat gets satisfied.

    Setback+Recovery Period: 0.527 cu ft per hr per degree hr
    Regular Operation Period: 0.655 cu ft per hr per degree hr
    Setback+Recovery Period = 45.7% of full day on avg.

    Savings during Setback+Recovery Period = 19.5% w/o factoring solar radiation benefits to regular operation periods

    Savings during full day (not factoring solar rad benefits) = 8.9%

    I've been making too many sacrifices doing this 2 weeks of testing so I'll suspend testing until I get the hourmeter + counter installed so I don't have to restrict my hot water + oven/range + dryer usages.

    EDIT: wunderground.com (not weatherunderground.com)