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Best WiFi Thermostat for Steam Heating?

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HeatingHelp
HeatingHelp Administrator Posts: 650
edited December 2016 in THE MAIN WALL
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Best WiFi Thermostat for Steam Heating?

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  • manny77
    manny77 Member Posts: 10
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    I installed an ecobee 3 last year after doing a ton of research. It has been a great buy. The remote sensors mean i no longer have to get up at time and adjust the thermostat. The install and setup was super simple and it is integrated with my smarthings and alexa devices.

    We have a one pipe steam system.
    Erin Holohan Haskell
  • Danscrew
    Danscrew Member Posts: 130
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    Ecobee 3 hands down the rest don't compare
  • LionA29
    LionA29 Member Posts: 255
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    @manny77 How does the system respond when a remote temperature is below the thermostat setting?
  • ajkowna1
    ajkowna1 Member Posts: 1
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    Hey Erin! You guys should create a link to a poll on Heating Help for what is the best WiFi thermostat. Happy Holidays everybody!
  • manny77
    manny77 Member Posts: 10
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    @LionA29 This is what i was most interested to observe. There is a setting called follow me which if disabled averages the temperature between the thermostat and sensor/s. The heating will turn on/off based on the avg. If follow up is enabled then the senors look for motion to kick in make a decision on when heating turns on/off. I have one sensor enabled. I have another 2 but don't feel i need to use them hence they are still in a box.
    LionA29
  • MilanD
    MilanD Member Posts: 1,160
    edited December 2016
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    Ecobee 3 question: how does the multiple temp sensor function? Does it average the temps from various places to keep, say, as close to 70 degrees everywhere? How does it decide which 70 is the one to shoot for, if, say, out of 3 sensors, one is 73, one is 70, and the third is 67? Will it then call for heat until the last 67 is at 70, but the other ones are at 73 and 75 by then, or will it keep 70 average, and let the other 2 temp sensors and rooms in which they are, stay at 67 and 73? How does this exactly work?

    We have 1 pipe steam, 3 zone system. I've managed to get the building to have similar temps everywhere as the system fires up in the morning. 66 set back overnight. First firing in the morning is to 69. Takes about 2 hours, and when tstat is at 69, other spaces are at 71 or so. After a few hours, some rooms cool quicker than others. At that point keeping things even becomes a matter of firing the boiler when main tstat still shows temp at 69. I now do it by programming tstat to raise the temp to 71 and then 72 every few hours. By keeping main tstat at 72 from about 3 pm to the evening, building stays at approx same comfort level. In the evening people leave and tstat sets back to 66.

    How does ecobee regulate this? Also, with cph, how does setting this help with efficiency? Can it be set to wait 5-10 min between firing?

    We now use a few years old Honeywell RTH8500 wifi thermostat with 4 daily settings.

    All our mains vent fine (all 3 mains are approx 180 ft long each, 2 are 2.5 inch and 3rd is 2 inch, all have new Hoffman 75 main vents), system is well balanced and all rads get hot evenly, meaning, each zone heats at the same rate, and last rads on each zone heat up at about the same time. I've instaled a few trvs on first 4 rads on the 2 inch loop, and that helped quite a bit to push steam down the run. We have a Weil McLane LGB 7, with a 50 gal condensate tank and feeder pump.

    I am mostly interested in economizing fuel use without having to do Tekmar controller, letting the boiler fire when needed and reducing cycling on pressure by delaying firing between pressure rising. Right now I do it with 3 degree setbacks. The system is full and all rads hot before pressure starts to rise, and the vaporstat is sett to cut off the burners at 7oz of pressure. There is of course, a lag between everything getting from 66 to 69 degrees, so what's the best way to delay boiler cycle by 5-10 minutes, and can Ecobee 3 do this?

    Thanks!
  • Danscrew
    Danscrew Member Posts: 130
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    Milan you should send those questions to ecobee. And see what they say The reason I installed the ecobee 3 on my mod con is i wanted to trend my boiler run times. By doing this I could set up my outdoor reset water temps to give me the longest run times. I have 3 sensors, the sensor in the basement is just set to monitor because its on a separate T-stat so i just can keep an eye on the basement temps. the other 2 i set to averaging back

    ( not sure how it averages the 2 sensors but the house stays right on set point with
    the other 2 sensors within 1 degree )

    to the main stat for the rest of the house there is a lot more you can do with this stat then the others read up on it and I am sure it will work fine. i also like the ability to see everything from my iPhone and sit on the couch and check temps from my iPad hope this helps somewhat
  • MilanD
    MilanD Member Posts: 1,160
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    Thanks @Danscrew . I will contact ecobee.
  • Koan
    Koan Member Posts: 439
    edited December 2016
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    @MilanD if and when you do , please post their answers - I have also asked about CPH and am curious as to if that adjustment can be made on an Ecobee 3 - so far I think not?
    Thanks
  • MilanD
    MilanD Member Posts: 1,160
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    I have some tight deadlines at work this week - will call Ecobee people as soon as I can and will post the findings here.

    Does anyone else knows of any other thermostat that can delay firing steam boiler after the initial pressure build and after burners cut-out? I am aware that some systems that are not balanced will, with this setting possible, keep rooms at the end of zones not heated, so this may not work for everyone. But, for balanced systems, this should work well, no? It would allow for a bit more latent heat to be disposed of into the space, and then the new steam would be introduced to continue, vs. cycling on pressure until the tstat is satisfied.

    On a side note, we had 20s here on Saturday. The room with the tstat which is in the office, usually has the door open and air circulating balancing the temp around the tstat. With the door closed on Saturday, the office never got over 69 and tstat was set to 71 (in expectation of colder day after a colder night). The result: the rest of the building was cooking on pressure all day - for 10-12 hours - before I looked at the tstat on my phone app and realized something was wrong and turned off the boiler remotely (by lowering the temp on tstat). 10 min cycle delay would have saved quite bit of fuel, by reducing the number of firing on pressure to 5/hour, vs, god-knows-how-many I had on Saturday.

    This would also have made things more comfortable in the building. I had emails waiting in my inbox this morning form people saying the rads were glowing and eyeballs popping (figuratively speaking) from how hot the rads were.

    Ugh...
  • SWEI
    SWEI Member Posts: 7,356
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    MilanD said:

    Does anyone else knows of any other thermostat that can delay firing steam boiler after the initial pressure build and after burners cut-out?

    I'm not entirely clear what you're describing here, but any stat set for 1 or 2 CPH should delay the re-fire once the call ends.
  • MilanD
    MilanD Member Posts: 1,160
    edited December 2016
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    That's my question: which thermostats have the CPH setting? I have Honeywell RTH8500 and it doesn't have the CPH. I'm looking for a wifi one that would have it. Does ecobee have it? Could not find any info online about that.

    More precisely, will cph delay restart of boiler burners after the first shut-off due to pressure cut-out on the pressuretrol/vaporstat?
  • SWEI
    SWEI Member Posts: 7,356
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    In looking at the manual for the RTH8500D, the CPH setting for heating is function 240. The only options are 1, 3, 5, and 9 -- I would set it to 1.

    For the record, Honeywell thermostat part numbers that begin with RTH are retail models and lack some of the settings which the contractor versions (TH) have.
  • MilanD
    MilanD Member Posts: 1,160
    edited December 2016
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    Thank you @SWEI . I looked at the manual prior to placing the tstat into service, and have set function 240 to 1. This did not prevent the boiler from cycling on steam this weekend (per my post above, and I'll explain below)...

    My question is if there is a way, other than with Tekmar 279, which I think can do this - although I only am tangentially aware what it does and not all ins and outs of it, - thus, is there a way to set the actual number of cycles to say, 3 or 4 per hour, or better yet, to delay each firing by 5-10 min after first rise to pressure, so that what happened to me this Saturday does not happen again? The following took place: tstat was in a cold room due to various factors that made it so this particular weekend, and it called for heat all day long. Entire building was burning up while tstat room was at 69 and tstat was set to 71. Had there been some kind of timed delay to firing the burners once the max steam pressure was reached, this would have much improved both the comfort of the building and needless waste of fuel. Instead, the building was cooking all day with boiler cycling on pressure.

    I'm aware that for systems that are not balanced, this delay would make for cold rads on the end of zones/loops. Our system is well balanced, everything vents well, and everything is nice and hot, including all the last rads on each of the zones, before pressure rises (well, aside from this happened this past weekend with the room where tstat is). We have a one pipe steam, op pressure is set to 8 oz cut out with a 4 oz reset. It really doesn't matter if reset is 1oz, it quickly goes back to 0 after burners shut off. Matter of fact, by the time it fires up again at 4 oz, often if not always the condensate return tank pumps new water into the boiler, and it quickly goes back to 0 psi. I don't have the exact EDR, but we have 29 radiators on 3 zones and EDR was done when new LGB7 replaced the old LGB11 (yeah, I know!).

    And yes, that tsat I did purchase online. Not being a pro, I didn't know there were differences, that is, now that I'm on this board I am learning a lot of new things.

    So, question is - with this long explanation - how to time-out burners for 5-10 minutes after the first (or each) rise to pressure even if the tstat is still calling for heat? I am aware that this may not be what everyone would want as some systems are not venting well and are not balanced well so some cycling on pressure is needed to get all the rads hot. This is not our case so the ability to delay firing by 5-10 min would allow for enough heat to continue to radiate out of the hot rads before new steam was to be introduced back, In essence, this would both save on fuel and make the building comfortable.

    Thanks again to you and everyone else who's taking time to read through my essays... :smiley:
  • MilanD
    MilanD Member Posts: 1,160
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    I'll start a new thread on this question.
  • Jamie Hall
    Jamie Hall Member Posts: 23,419
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    It sounds to me that you may be looking for a solution to a problem which doesn't exist.. however, a simple way to approach doing what I think I hear you wanting to do would be to add a relay to the pressurestat/vapourstat which would allow for a time delay on reclose. That is, the pressurestat/vapourstat would open on pressure in the normal, simple fashion. It would then reclose rather quickly, as the steam collapsed. However, instead of directly restarting the burner you have a time delay relay in the circuit which would prevent the burner from firing for an additional five to ten minutes.

    Mind you, I don't think this would accomplish much. In that time the system would get back to atmospheric and the boiler would cool below a simmer, so you would spend additional time and fuel reheating the boiler and getting the air back out of the system. But... whatever.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    MilanD
  • Koan
    Koan Member Posts: 439
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    @MilanD - In the case of the open door to the room with the tsat, if you have an Ecobee 3 with remote sensors would that work to keep things more even??
  • MilanD
    MilanD Member Posts: 1,160
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    Koan said:

    @MilanD - In the case of the open door to the room with the tsat, if you have an Ecobee 3 with remote sensors would that work to keep things more even??

    @Koan

    That's what I'm thinking. But the question is if it will do what I want it - and that's why I need to call ecobee and ask how it averages the temps and which tstat it uses as a bench-mark, if any...

    Then, I suppose, second part of this is - how do I get the boiler to delay re-start once it gets to the set max operating pressure? I want to let it give off latent heat for 5-10 minutes, then restart, rather than cycle on pressure for some time.

    Perhaps ecobee will in fact solve this if it somehow averages the 3 temps and calls the temp 'satisfied', with one of the tstats still registering below the set temp.
  • MilanD
    MilanD Member Posts: 1,160
    edited December 2016
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    @Jamie Hall

    Great answer! This is exactly what I was wondering if can be done. So there is a delay switch that can be added to vaporstat to delay it on reclose. This is what I'll be doing.

    We now have a question if fuel burned when cycling on pressure is less vs. fuel burned after 5-10 min delay in order to get the water to boil again, create steam and move air out. Hmm... if venting is as good as it can be, my assumption is that this would quickly create steam and get it to rads.

    I didn't consider this angle, as you call it - problem that doesn't exist. I've approached it from other forum questions where oversized systems cycle on pressure until all air is expelled (not enough venting capacity for the amount of steam created), and all rads hot. This creates excess fuel consumption. I'm wondering if the well-balanced system, properly sized and venting as it should, could also have this happen under certain circumstances, as it did to me last weekend.

    On such system, there is, sometimes, a delay between the time radiator is hot and the room is warm and the boiler reaches its max op pressure (esp. after set-back on especially cold days, or if tstat is not satisfied because someone turned off the rad in the room where it's located...) I am talking 5% of the time when this happens and I'd like to make sure we don't waste fuel.

    So, what is better? On a balanced system that works as it should and gets hot on the initial firing, all rads hot before pressure rises, is it better to then cycle on pressure until tstat is satisfied (on those cold days), or is it better to delay firing and allow rads to dissipate some heat into the space before getting new steam to them?

    I am assuming that it would use less fuel to delay firing the boiler by 5-10 min and allow latent heat to dissipate, vs. cycle on pressure until tstat is satisfied. I would think that with only a 5 min delay, well insulated and still hot pipes, good venting and insulated condensate tank (I have one of those systems no one here seems to have seen, 1 pipe system with FT and Warren Webster 78 traps, and a condensate return tank), this would create savings in fuel consumption. Esp. as my now inulated condensate tank will have no problem at keeping the water in it at about 200 degrees for 5 - 10 minutes, nor would boiler loose too much heat waiting 5 minutes.

    So, question is - will it be more fuel to bring back steam from 5 min delay to the point of producing the steam again (say 7-8 min total), or will it be more fuel if the system is cycling on pressure for 7-8 minutes)...

    I am talking about my particular system that's all hot and at capacity at 8 oz of pressure, and most of the times, does not cycle on pressure at the 3 degree setback.

    Here's a link to the thread I just started, explaining my particular situation.

    http://forum.heatinghelp.com/discussion/160248/how-to-delay-boiler-from-firing-again-right-away-after-max-op-pressure-is-reached
  • Koan
    Koan Member Posts: 439
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    called Ecobee support. on hold for 43 minutes waiting and no one answered. what if I owned one and the heat wouldn't come on?? gotta wonder about that low level of support.
  • MilanD
    MilanD Member Posts: 1,160
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    Koan said:

    called Ecobee support. on hold for 43 minutes waiting and no one answered. what if I owned one and the heat wouldn't come on?? gotta wonder about that low level of support.

    That's terrible. Perhaps all these people with steam systems are all calling at once...

    KoanMichael_Zaborskis
  • Koan
    Koan Member Posts: 439
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    @Jamie Hall

    A delay may make sense. I assume this is the effect of a CPH setting being lowered

    Here is my take on the the cycling issue with an oversized boiler (as is mine). Boiler fills mains as air vents quickly, then radiators as they vent more slowly. At some point, there is steam in the entire system (hopefully). Then all the traps see steam and close. Adding extra steam then builds pressure because the steam in the radiators cannot condense fast enough to give it's heat into the rooms and has no where to go. Boiler cycles on 8 oz. pressure as radiators try to convert steam back into water by dissipating heat. As they do so and pressure falls to 4 oz. boiler fires up too soon because radiators still cannot dissipate heat into the room fast enough.

    1) The amount of reasonable time delay would be base on how fast the radiators cool back down. The amount of delay that would be costly would be in having to reheat the thermal mass of the water to produce steam. You could measure the boiler water temperature to see how fast it cools down, however I recall the heat to produce steam from 212 water is pretty significant, much more so than to raise the temperature of the water.

    2) Assuming the water is at 92 degrees, to go to 212 takes 120 BTU per pound. If it were at 112 degrees to start it would take 100 BTU per pound. to get 212 degree water to stem takes 970 BTU per pound. so the losses are not as much in reheating water, but in getting hot water to steam. Once the boiler pressure goes to zero because no water is boiling, this energy has to be put in again.

    3) The optimum is probably different for each system. heating water to make steam that cannot be used doesn't make sense

    4) Barring an expensive monitoring setup like a Tekmar, the only tool for dialing in a delay would be trial and error monitoring your hardest to heat radiator outlet temperature You could then try different delays and monitor fuel usage, or just see if cycling is avoided. The problem with this approach is that there can be no real control condition to evaluate real fuel efficiency.

    5) One idea that might help would be to set the Vaportrol to cut out at 8 oz. and start back at 1oz.?? Is there any reason to not do this?? why are we set to kick back in at 4 oz.? Seems that even if we were cycling at least the the cycle would be longer and allow the radiators to condense a little more... maybe the difference is negligible. I'd love to hear some feedback on this one.

    6) Other than that if you are cycling and all rads are hot, through trial and error you could see how long before the radiators cool enough to prevent cycling and set your delay there?

    just my 2cents
    MilanD
  • Jamie Hall
    Jamie Hall Member Posts: 23,419
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    Of course the ideal system would be one in which the burner and boiler was exactly the right size to continuously supply steam at exactly the rate at which the radiators were condensing it. Then it would just sit there and run until the thermostat was satisfied -- which, hopefully, would anticipate the heat loss of the building to keep the temperature from overshooting from the stored heat in the radiation.

    Right...

    Back in the day, at the cost of efficiency, this was done! With a draught damper on the coal burning boiler which was regulated, very very sensitively, by the pressure in the boiler -- a modulating burner, in fact, of a century or so ago. The efficiency was ghastly. The evenness of the heat was outstanding.

    The modern similar ideal would be a burner which modulated on pressure in exactly the same way and, other than not being aware of a control for a modulating burner for pressure, there isn't all that good a reason not to do it.

    However, we can do it. The start and shut down cycles of a modern oil burner (many have 15 second purges on both ends) waste remarkably little heat -- and almost no fuel. Therefore, in terms of overall fuel efficiency, the optimum approach is to cycle the burner on and off so as to maintain the steam pressure within an optimum range for the system, minimizing the off time (so the water and the boiler never get to cool off much, which is a loss) and adjusting the on time to maintain the pressure below whatever is right for the system.

    So... set up the vapourstat to cutout at the optimum system pressure. The cutin is an interesting one. On many systems, it actually makes very little difference, as the system pressure drops fast enough that the cutin is reached even before the post purge is over. One can play with it... But if the cutin is reached before the post purge is over, then the pre purge will start very quickly -- there is a short time delay -- and off you go again.

    Or at least that's the way it seems to me...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • MilanD
    MilanD Member Posts: 1,160
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    So really the question is the amount of fuel burned to get that water to steam, in BTUs.

    212 degree water can have both 500 BTU and 800 BTU and 1150BTU. If steam is made at 1150, let's say we start with: 70 degree water + 142 BTU/pound to 212 degree water +970 BTU/pound to steam=1112 BTU/pound.

    If boiler cycles on pressure, from my novice observations, at 8oz cut out, it doesn't take a whole lot of time to get that steam producing again. This means that BTU input to that water that's already in the boiler sitting with all the 1112 BTUs it can store at 8oz of pressure (actually it's more like 1150BTU if we started from 32 degree water - so let's call it 1150 BTU).

    So with 1150 btu in per pound of water, the boiler at 8oz pressure, trol (vapor or pressure, whatever) will turn the burners off. At this same time, the steam in the rads is giving off heat and after it gives off its' 1150 btu - 970 btu, water condensates into 212 degree water with latent 212 btus still in it, and starts slowly making its way back to boiler. (*side note, 32 btus we got for free as it was liquid water at 32 degrees when it came from the water main).

    As all this steam collapses back into liquid water, pressure in the system (and thus the boiler) goes back down to 7,6,5,4,3,2,1 oz... At this point we still have water in the boiler that is close to 1150 BTU, but slightly less, and less for the amount of BTUs burners did not put in while they were off.

    One can look at the chart on your boiler and see what that max btu rating is, and see the efficiency and then see/calculate what BTU amount goes into water per hour.

    Here in which lies the balance: efficiency. IF you are (your boiler, that is), say at 80% efficiency at the boiler, 20 out of 100 btus that are burned up in fuel go up the chimney. At this point, you would look at whether the BTU loss from the hot water sitting in the boiler is greater than 20% (-230 btus/pound/h). If so, cycling on pressure is better. If not, delaying firing is better. I somehow have a hunch delaying firing is better, and better because you also have heat-loss for the building and the fact that even at 212 btu, hot water and hot radiator still gives off BTU energy into the space and there is delay in feeling this BTU energy dissipating into the space.

    No?

    So, question is how do you look at btu loss in the boiler? I assume each boiler and system will be different (boiler insulation, pipe insulation - to minimize pick-up factor between cycles), draft under the boiler (if no auto draft damper, which I assume 90% of people don't use as they are 1st to break), boiler room temperature (hotter the better??)... But there is also building heat loss to rad btu drop ratio, no?

    You would have to time firing cycle-to-steam, and then steam-at-boiler to steam-at-rad time, for each minute off to zero this in, then how it transfers to heated space (BTU in vs heat loss), and this would depend on what the outside temperature is at that time. Sounds complicated, huh?

    So maybe, just look at time it takes to make steam after 1, 2, 3, 4 etc minutes off and how it feels upstairs to figure it out that way. I still think delaying firing will save fuel.

    Wow, I didn't know I knew all this...
  • Jamie Hall
    Jamie Hall Member Posts: 23,419
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    Another way of looking at it is to consider at what rate the radiation can release heat. This is a variable, of course, depending on the room temperatures involved. Then what you want to do is to add heat to your boiler water at exactly the rate the radiation is releasing heat, and to do this with the minimum of loss. Now to my way of thinking, any time the boiler isn't firing, it's losing heat -- not to the steam, but to the space and to the draught. Any heat lost that way must be made up -- with none going to the radiation -- before the boiler starts to steam again. So to my way of thinking, the way to minimise the loss is to minimise the off time of the boiler -- which means to shorten the cycle as much as possible. This will be limited by the post and pre purge cycles, if any, of the burner.

    I can see some of your points, but I would note that the hot water sitting in the boiler (where you are considering the efficiency of the burner vs. the heat loss from the boiler) is contributing nothing at all to heating the building. It's just sitting there. Nor is there any hot water to speak of left in the radiation -- or at least there shouldn't be.

    So I'll still go for the shortest possible on/off cycle, using pressure as the surrogate for heat release rate in the radiation.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Koan
    Koan Member Posts: 439
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    @Jamie Hall my oversized boiler burns gas, and as it is oversized I'm losing a lot up the flue. I don't have those purge cycles like an oil burner. I like the idea of examining the thermal behavior of the radiators, but I don't see any sense in sending heat to them they cannot distribute to the room. It seems then you are just cycling and heating the boiler room.
    @MilanD I like the approach of comparing one loss vs another - I also think you are on to something there. My thought is that water producing steam probably loses the latent heat of vaporization (970BTU /lb) quickly, though I do not have any evidence. I guess we could wait different times and see how long it takes to rebuild pressure. It just still seems that if you are cycling you are still making heat but it seems it is not distributed very well.

    I am sorry about going into the CPH stuff so far under this thread - that is my fault. We can continue that interesting discussion under a different thread maybe?
    Honestly my boiler is rated 750 EDR and I have 399EDR of radiators, so my best bet will be either a normal sized boiler or to try to heat my neighbors house as well! :)

    It is a long standing accepted fact that cycling on pressure diminishes efficiency. For now I am willing to accept that fact, and to get back on track just looking for a good WiFi thermostat that has either CPH settings of a delay that acts to serve this function.

    I have read good things about the Ecobee 3, and really want to see if it has a true CPH setting or some proxy that will serve nearly the same function.

    If not I have to determine if I can find a Honeywell model that has CPH and remote sensors?

  • SWEI
    SWEI Member Posts: 7,356
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    Koan said:

    if I can find a Honeywell model that has CPH and remote sensors?

    The new T6 Pro series has this at a very attractive price. TH6220U2000 and TH6320U2008 are both available for less than $100. Shameless plug: We sell compatible remote sensors (American-made, far nicer enclosures) at very competitive prices.
    zvalve
  • j a_2
    j a_2 Member Posts: 1,801
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    Deriva, intelliSync.....sold by FW Webb....works with two wires and painless set up....Does the job....
    zvalve
  • SWEI
    SWEI Member Posts: 7,356
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    If you want WiFi, move up to the TH6220WF2006. Still quite affordable.
  • j a_2
    j a_2 Member Posts: 1,801
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    What options does it offer for residential steam....that some others may not......Does it require a third wire...Not much one can do with steam except monitor it...adjust it up or down. And program it to your living conditions....
  • Michael_Zaborskis
    Options
    Take a look at the ecoBee
  • stonehouse
    stonehouse Member Posts: 16
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    @Koan, I have a 1 pipe steam using a Burnham MegaSteam and a vaporstat. Old stonehouse with open cell insulation (poorly installed, but we didn't know better at the time).

    I've used a number of thermostats including the Nest and am now quite happy with the Ecobee. It seems to cycle the boiler less than the Nest but maintain a more level temperature in the house.

    The remote sensors will average if you put the system on "Follow me". You can also decide which sensor participate in which mode (Home, Away, Night, Visitor). So there is some flexibility.

    It does require a "C" wire but comes with a "PEK" (power extender kit) that lets you "fake" it out. You can see the instructions here: https://www.ecobee.com/installing-your-ecobee3/

    I've had good support from Ecobee, but have not needed it often. I would suspect you called during the very busy holiday season...

    I know this doesn't answer all your questions, but I hope it helps. All in all, I really like the unit and have recommended it to others who like it as well.

    Alex (The Wire Nut)
    LionA29MilanDKoan
  • MilanD
    MilanD Member Posts: 1,160
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    Of course the ideal system would be one in which the burner and boiler was exactly the right size to continuously supply steam at exactly the rate at which the radiators were condensing it. Then it would just sit there and run until the thermostat was satisfied -- which, hopefully, would anticipate the heat loss of the building to keep the temperature from overshooting from the stored heat in the radiation.

    Right...

    Back in the day, at the cost of efficiency, this was done! With a draught damper on the coal burning boiler which was regulated, very very sensitively, by the pressure in the boiler -- a modulating burner, in fact, of a century or so ago. The efficiency was ghastly. The evenness of the heat was outstanding.

    The modern similar ideal would be a burner which modulated on pressure in exactly the same way and, other than not being aware of a control for a modulating burner for pressure, there isn't all that good a reason not to do it.

    However, we can do it. The start and shut down cycles of a modern oil burner (many have 15 second purges on both ends) waste remarkably little heat -- and almost no fuel. Therefore, in terms of overall fuel efficiency, the optimum approach is to cycle the burner on and off so as to maintain the steam pressure within an optimum range for the system, minimizing the off time (so the water and the boiler never get to cool off much, which is a loss) and adjusting the on time to maintain the pressure below whatever is right for the system.

    So... set up the vapourstat to cutout at the optimum system pressure. The cutin is an interesting one. On many systems, it actually makes very little difference, as the system pressure drops fast enough that the cutin is reached even before the post purge is over. One can play with it... But if the cutin is reached before the post purge is over, then the pre purge will start very quickly -- there is a short time delay -- and off you go again.

    Or at least that's the way it seems to me...

    Just a little follow up on the thread :smile:

    Thank you @Stonehouse for getting the info on Ecobee 3. So, there is a "follow me" average feature to it. That's great.

    With the different thread and help by many knowledgeable people, it turns out our LGB7 boiler has a high-low-high firing feature (and that's why I'm responding to @Jamie Hall about modulating old coal boilers with pressure rise and choking the flame by cutting the air, until pressute drops and air is reintroduced to the coal). LGB 6 and up has gas valve train which comes standard with the boiler, that can be set to full BTU input first, then lowered to less BTU (basically, having 2 stages!), which will do exactly this: fire down the burners to, say 60% of max btu rating (this can be set to different % of max, down to min allowed per spec), and as long as psi stays between cut out and cut in, it will stay at the lower btu input rate. If it falls below cut in, burners will kick back in to full throttle. In conclusion, Weil Mclaine LGB 6 and up can, for all practical purpose, be fired in 2 stages. Best we can hope as far as modulating goes. I already met with our mechanical company and am waiting for them to come back and enable this feature. Why it is not an option on smaller systems is at this point, mystery to me, but I will ask our guy for his thoughts on that. I'm assuming it's added cost of the gas valve train vs. benefit for smaller boilers. I would think this would also be solution for oversized systems too, but I yet don't know enough to competently answer this question.

    Full thread on this is here:
    http://forum.heatinghelp.com/discussion/160248/how-to-delay-boiler-from-firing-again-right-away-after-max-op-pressure-is-reached

    One last thought, and a great new tech solution for large buildings, in case you missed this thread - it is brilliant and very much not silly at all! Essentially, solves this very problem for very large buildings, creating an ultra-smart system, that's also both cutting energy use by between 35% - 45%, AND, turns the rads into thermal storage devices. Quite brilliant!

    http://forum.heatinghelp.com/discussion/160675/this-is-a-silly-idea

  • Koan
    Koan Member Posts: 439
    Options
    @stonehouse
    All that is left to really upgrade rather than replace the boiler is the thermostat, a Honeywell Chromotherm 8090 from 1969.

    I should be able to run a common C wire

    Thank you for the input!

    We have 11 radiators totaling 399 EDR and a 750 EDR boiler (American Standard circa 1969) on a 2 pipe Hoffman vapor system. It was cycling on pressure most of the time. We had all but the largest rads refinished, flushed them out (got a lot of stuff out of them) and removed the radiator covers (now that they look so good!) Next I re-piped the Hartford loop and some of the near boiler wet returns as there was only about 1/4" diameter passage for the return. Installed valves at the same time to flush out the wet returns every year. Biggest thing was getting the mounds of crud out of the boiler with a 120psi wand. It took and entire day to flush that beast out. Cleaned the clogged pigtails on the gauge and Vaporstat. Replaced every trap cage thanks to @Sailah. Next @Steamhead helped out with an overall inspection, a new gas valve (dialed back a little bit ) and a combustion test to make sure all was well. After that a few house of skimming after using Steamaster and the cycling has completely stopped. All rads get hot - even the 30 section one though it takes a while. Master bedroom gets a bit hotter than all the other rooms (14 section) - i guess that radiator is a bit too big - maybe we put the cover back on that one.

    Even though the boiler is massively oversized, it is running great, usually at 2-3 oz pressure and no more even when recovering from a 5 deg setback. Amazing what cleaning the system out can do, and getting good advice for all the kind people here.

    I like the Ecobee 3 because of remote sensors. We are adding hi-vel ac in a month or two as well.

    Thanks again for the info!
    MilanD
  • apraetor
    apraetor Member Posts: 16
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    I love my Ecobee 3. Our house is single zone, one-pipe steam. I put the main thermostat on the ground floor, replacing the existing Honeywell. I then put remote sensors on the second and third floors. The Ecobee has 3 time periods per day you can program: Home, Away, and Sleep. I have all three set to the same temperature.

    However, a great feature you can change is which sensors are used for which time period. For example, during the Home and Away periods all 3 sensors are used; set to 70F that means the average of all 3 sensors is 70F. During Sleep only the sensor on the 3rd floor (master bedroom) is used. Our first floor tends to be cooler, so this results in the heat running slightly less often.

    I have the "follow me" setting disabled, but in theory it can automatically use the average sensor temp of all occupied rooms, whether that's one or all 3. As is it keeps the whole house within 2F, so I don't see the need.

    One nice fail-safe is that you can specify the threshold for what means a sensor is glitching, or window was opened, etc. Currently I have it on the default, where any sensor off by more than 10F is ignored. But you can customize or disable that feature. You can also receive mobile alerts if the temp goes above/below whatever thresholds you set.

    Although you cannot set CPH directly, you can set minimum cycle duration, minimum time between cycles, and swing (0.5-3.0F in 0.5F increments). I'll post a screenshot of the initial learning period when I get a chance; the first 12 hours or so I had 1F overshoots followed by drops to 68/69F (same as my old Honeywell), but now it has learned the behavior and the house holds pretty rock-solid at 70F. I don't have an outdoor temp sensor, so it pulls that data from the internet, but that seems to be close enough for it to correctly determine how early to start heating.
  • Eastman
    Eastman Member Posts: 927
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    @apraetor

    Does it really use the outdoor temperature, or is just for display?
  • apraetor
    apraetor Member Posts: 16
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    Yea, it does factor it in, it's called DataRhythm. It builds a predictive model correlating the rate of heat loss and outdoor air temperature.
  • Eastman
    Eastman Member Posts: 927
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    Those are some awesome features. What cycle settings do you use? I wonder if it can factor in wind data.
  • nicholas bonham-carter
    Options
    I still think the Honeywell VisionPro, set to a constant 68, with remote sensor in the coldest area of the house is the best choice. Any sensor in a locked office will run the boiler until that room (possibly underradiated), is satisfied, no matter how many timers you have on the system.
    In the case of a system with 2-stage firing, the vaporstat can be used to cut out the high fire, and go to low fire. Assuming you have good main venting this method should work well.—NBC
    Motorapido
  • apraetor
    apraetor Member Posts: 16
    edited February 2018
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    I have the minimum cycle duration set to 5 minutes; I'm experimenting with giving it the ability to short-cycle, to see what it does. All my radiators are basically balanced, and I can see 5-minute cycles being useful on very cold days where the heat runs for 30 minutes out of the hour on average during the night.

    The swing is set to 0.5F, which is actually plenty. With a 1 degree swing the system runs so infrequently (except on very cold days) I wind up burning a bunch of fuel to reheat the boiler. Not sure which approach saves fuel in my case, but:

    I'm logging everything to csv and my wife is a data wonk, so I'll have some nice charts after the winter. I promise! It's natural gas, so I have csv log data for daily fuel use, as well. Gonna chart all the data points and we can all pick over it and argue :)

    @nicholas bonham-carter I do think I will be installing a vaporstat for long burns on really cold days. My low psi gauge never shows much pressure on typical burns, but when temps drop to the teens it does run for long enough to start building somewhere around 1 psi.

    If you are offering to install the staged burner, then j won't stop you. I'd love one, granularity of control is never a bad thing in itself. But I'm not sure the fuel savings would justify the cost, unless you are sending the Boiler Fairy on over!