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New thermostat

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We have three zones for AC and one zone for heat, we have a one-pipe steam heat system. We have three different designs of honey well thermostats. I want to update our thermostats to smart and link them up so it’s easier to control the ac.

is there a recommended smart thermostat for steam heat?
djd

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,322
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    Technically pretty much any thermostat can be used for steam hear. Most of us seem to prefer Ecobee or Honeywell, and almost all of us have various horror stories to tell about Nest themostats vs. steam heat.

    The joker is that "smart" thermostats -- that is, those that sense and adapt to current conditions -- are remarkably ill suited to steam heat (or for that matter to any slow responding heating system -- radiant floors are the worst, but many hot water systems are problematic as well). The best way to get them to behave is to disable ALL the "smart" learning features, and limit them to one small setback, at most, per day.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    MarjPinard
  • tsayles50
    tsayles50 Member Posts: 36
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    Thank you!!
  • ahallasjr
    ahallasjr Member Posts: 5
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    I have a one pipe system and the most inexpensive Nest thermostat that was provided by my utility. Its performance is outstanding. For any given outside temp it learned when to start up and cool down to maintain the desired temp. I couldn’t be more pleased.
  • gerry gill
    gerry gill Member Posts: 3,078
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    We have used Ecobee without issues on steam.
    gwgillplumbingandheating.com
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • Robert_T
    Robert_T Member Posts: 9
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    We own a number of buildings with steam heat both one and two pipe steam. With over fifty years of experience with these systems, we have found that you must use a thermostat with an adjustable anticipator for one-pipe systems. This controls the length of the cycle and consequently the return of condensate to the boiler. Very few high-tech stats can do this properly. Even the Honeywell in the round no longer has this feature. Fortunately, White Rodgers still makes a couple of them. We use Mod. #1E30N-910.
    Bill_Kitsch69Logik
  • Bill_Kitsch69
    Bill_Kitsch69 Member Posts: 48
    edited May 2023
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    Honeywell FocusPro-6000 series (5000 non-prog) is all I use. No doubt they have wifi 7000 or 8000 models that have the same steam background contractor programming. CPH - cycles per hour (note bottom) is your 'heat anticipator' adjustment. Using the background programming matrix with understanding along with Honeywell's adaptive recovery learning feature, one has broad latitude to set up a steam system/zone to a degree only surpassed by Heat Timer, at many thousand$ of dollar$.


  • billydick
    billydick Member Posts: 3
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    One pipe steam boilers are most efficient while boiling water and making steam. We have found the best programmable t-stats to use have an adjustable "swing" or temp differential. For example: With a four degree swing a stat set to maintain 70 degrees will not call for heat till the room temp drops to 68, and it will continue to fire till the room temp hits 72. You can use 2,3, or 5 degree swings if the occupants can tolerate it and are comfortable. Even a 2 degree swing will help efficiency and fuel costs. There is only so much hi-tech magic you can apply to a ninety-year-old one pipe steam system.
    exqheat
  • Logik
    Logik Member Posts: 11
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    I have a Honeywell Redlink non-programmable thermostat system. Since the thermostats connect by radio to the receiver in the basement boiler room, I can locate thermostats on the third floor or wherever I am spending time without running wires, and I can locate them much closer to the a radiator than the original so they don't overshoot the set temp.
    As an experiment, I use Amazon Alexa to make the system programmable. An Alexa "routine" lowers the Honeywell thermostat set point to 65 at bedtime, and then starts moving it up 1 degree each half hour starting at 5, so we are back to 70 by 7:30 without overshoot. Although I rarely change it, the ramp-up routine is easy to modify from the phone app without being near the thermostat. I believe a more complicated routine could modify the ramp up depending on the outdoor temperature, which Alexa "knows". And of course if I leave the house I can ask Alexa to drop the set temp without going near the thermostat. And I am sure Google Assistant could do the same.
    So far (2 years) this has worked very well.
  • zackwatt
    zackwatt Member Posts: 81
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    Ecobee has a steam/boiler selection in the initial setup.

    Been using it for 5 years and absolutely love it!

    I use a defined schedule, not a "smart" sensing one. I keep my temperature increases at 2 degrees.

    Day 70 - Evening 72 - Sleep 68 - Wake 70
  • tanklessman01
    tanklessman01 Member Posts: 11
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    Any smart thermostat can do the job.

    Things to remember;

    At least 3 wire thermostat wire
    R-W-C for any boiler.

    At least 5 for 1stg gas heat with 1 stg. AC,     R-C-W-Y-G 

    At least 6-8 for Heat pump 
    R-C-W2-Y-G-O/B-E

    I have two  Smart Thermostats made by Honeywell for Amazon,
    One for hot water boiler, one for heat pump I only use for cooling and as back up heat, in case boiler goes down.

    İf you need outdoor sensor,..
    1- you need 2 additional wires 
     2-forget Amazon stat, 
    It has sensor connectors but not functional.

    One Note for the heat pumps,...
    I use inverter heat pumps that's made to work with central ducted systems.
    They energize the reversing valve in Heat mode(B terminal)
    Most ordinary heat pumps use
    "O" terminal to energize in cooling.
     
    With the utility company rebates, they were pretty much free. 
  • Bug512
    Bug512 Member Posts: 52
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    I have a Honeywell T10 in my home. It works flawless. My nighttime temperature is 68 and day is 70.
    Gene in Northern NJ
    NJ HVACR License 19HC00537600
  • PEvans
    PEvans Member Posts: 116
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    I went through all of this about a year ago, reading all the posts on this forum, and here is my $02. FWIW I was an early adopter of Nest thermostats in my last house and I am a big booster for the right applications.

    You have to distinguish among the "smart" functions. First, echoing what Jamie Hall said, "smart" thermostats like the Nest use ever more inputs -- time of day, ambient weather, occupancy sensing, etc. -- to turn down the heat for short periods of time when it is not "needed." This is appropriate for a fast-responding heating system like forced air. It is not as well suited for a heating system with a large thermal mass that may take minutes or hours to warm up and then overshoot. With steam heating you really don't want the heat to shut down if you leave for an hour on a cold day; that's why people here suggest disabling these features. You may not even want to turn the setpoint down at night. Some here suggest only a degree or two at most.

    Some thermostats have programming features that allow you to directly specify the maximum cycles per hour or tell the thermostat that this is a steam or pumped hot water system so it won't cycle and overshoot as much. I found it really hard to determine what a given thermostat does even reading the manuals, particularly for so-called consumer grade thermostats that you buy at retail outlets. If the thermostat even has a programming menu it may not be documented in the manual. Notwithstanding the best efforts of people on this forum, you may end up buying several thermostats and contacting tech support to find out what they do and don't do.

    The second "smart" function is the ability to monitor and control the thermostat remotely, by phone or whatever. I think this is essential for a new thermostat where you are not sure how it is going to work with your system. You will probably not have access to the deep setup menus from your phone, but you can watch the conditions when it calls and stops calling for heat and learn the behavior over time. This is even more essential if you have multiple thermostats on multiple systems or zones that may argue with each other. We are all geeks here. It would be nice if thermostats created time-series data logs that you could download and examine what is happening over time, but they don't, or at least they don't make it very easy.

    The third "smart" function is the ability to inform the thermostat(s) with temperature readings elsewhere in the space. There is no guarantee your thermostat is placed in the most representative location or the most important based on use. I don't have direct experience with this but I sure wish I did.

    In the end I installed and kept a Honeywell TH8321WF (“VisionPRO 8000 series”) for my steam heating system. It is OK and Honeywell tech support was really good. It has no occupancy sensing features. It also does not support remote temperature sensing. It has deep, dark menu settings for steam and hot water heating, but no directly-settable cycles per hour (Honeywell said the available settings do the same thing). It does not crazy overshoot and I have learned to control it. I can control and monitor via phone and the web app. My system has two zones with motor-operated valves and the old thermostat was driving the valve operators, not just signalling the burner control. So I had some other issues to sort out.


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,844
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    ahallasjr said:

    I have a one pipe system and the most inexpensive Nest thermostat that was provided by my utility. Its performance is outstanding. For any given outside temp it learned when to start up and cool down to maintain the desired temp. I couldn’t be more pleased.

    I can only imagine @pecmsg expression after reading this one.

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    pecmsgexqheat
  • pecmsg
    pecmsg Member Posts: 4,859
    edited May 2023
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    ahallasjr said:

    I have a one pipe system and the most inexpensive Nest thermostat that was provided by my utility. Its performance is outstanding. For any given outside temp it learned when to start up and cool down to maintain the desired temp. I couldn’t be more pleased.

    I can only imagine @pecmsg expression after reading this one.

    I was staying out of it but as long as you asked:


    NEST

    S
    U
    C
    K
    S


    RIP Harry
    https://youtu.be/XeZJ6WSVVAk?t=347
    EdTheHeaterMan
  • rberq
    rberq Member Posts: 6
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    PEvans said:

    I found it really hard to determine what a given thermostat does even reading the manuals, particularly for so-called consumer grade thermostats that you buy at retail outlets.

    I have a cold-start boiler (water, not steam) and five cast iron radiators. I get temperature overshoots of 2 to 3 degrees even though the Lux thermostat has only a 1/2-degree swing. I have been searching for a “modern” programmable thermostat with a decent adjustable or “learning” heat anticipator, but at $100 to $300 a shot I can’t afford to try them all. Echoing what PEvans said, it’s very frustrating that the literature does not describe HOW their cycles-per-hour works – just trust me, seems to be the attitude. I wired in an interval timer that I can adjust for burner-on / burner-off duration. Essentially, the thermostat turns the timer on/off, and the timer (when on) turns the burner and circulator on/off. 15 minutes on and 15 off works pretty well in winter, 10 on and 15 off is better for shoulder seasons. Neither one works great when recovering from nighttime setback. Seems there should be a thermostat that would do all of that all by itself.

    exqheat
  • PEvans
    PEvans Member Posts: 116
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    Short of what rberg is describing, I think what a "modern" thermostat is going to do in a steam system is call for heat and fire the burner primary control, then the system will run until the pressuretrol or vaporstat interrupts it , short-cycle against the pressure setpoint for a while, and when the thermostat thinks it is satisfied, shut off, with the system continuing to put heat out for the next hour or so, overshooting the desired temperature.

    I think one key is to avoid trying to overcome an ambient to setpoint temperature difference of more than 2 degrees. My night time setback is only 1 degree, and it is there more to get the radiators warm for when we get up in the morning.

    We keep the temperature setpoint fairly low and augment with room heaters. If I want to warm things up in the evening a bit I put in a temporary temperature setpoint with my phone, and shortly after the heat comes on return it back to the regular setpoint. The thermostat seems to know it is not going to get to run again for an hour or so, so it runs long enough to distribute steam throughout and warm things up before it stops calling.
  • djd
    djd Member Posts: 18
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    we have Ecobees on a very similar setup to yours (2 zone AC and 1 single pipe steam).

    love them overall but couple niggles to be aware of with how they work together (or not) and with the smart sensors.

    My 1st floor ecobee controls the boiler. All winter long it is blissfully unaware of the 2nd floor temperature reading on my upstairs ecobee. Wish I could “group” them to avg temp throughout the house, or “follow me” like for the smart sensors, seems like a natural use case.

    On the smart sensors themselves then, I have one in my 2nd floor kids room. In the winter I need to pair it to the downstairs ecobee which controls the boiler. In the summer though I need to unpair and repair it to the 2nd floor ecobee which controls that zone 2 AC.

    it only happens 2x a year but it’s clunkier than it should be imho.

    net net though still like them a lot and way better than any dumb thermostat out there
  • BillyS
    BillyS Member Posts: 8
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    Here is my experience from five years ago. I have a one-pipe steam system with two wires (R / W) from the T-T connection to the thermostat, no common wire. Complete disaster. I work for a utility and got the Nest as a discount as part of their energy efficiency program. I complained internally that Nest had no real solution in my case. They said I was the exception. I can't sell the thing either or I'll risk getting disciplined. That happened when a coworker decided to buy a bunch and resell them on ebay.

    https://forum.heatinghelp.com/discussion/167014/nest-thermostat-and-steam-heat
  • Athana
    Athana Member Posts: 104
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    "We have found that you must use a thermostat with an adjustable anticipator for one-pipe systems. This controls the length of the cycle and consequently the return of condensate to the boiler."

    Hi..What do you adjust it at ? The Honeywell 10 year old Digital Thermostat we have basically hits the temperature then turns back on when it senses a 1 degree drop.
    Can I ask you other than the local tune up Service Petro/Pierson's (here in New Jersey) does what
    is the main jobs that need to be done once a year to have it run efficiently ?
    Thanks so much before hand
  • pecmsg
    pecmsg Member Posts: 4,859
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    That depends on your system. You need the amp draw on the t-stat when calling. 
  • rtayloryes
    rtayloryes Member Posts: 1
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    I always set my thermostat down to 55 at night and kept the boiler off for my one-pipe system.
    I loved how it cam up to temp predictably in the morning with nice hot rads. The time to boil the water and heat all the rads was very predictable.
  • pecmsg
    pecmsg Member Posts: 4,859
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    I always set my thermostat down to 55 at night and kept the boiler off for my one-pipe system. I loved how it cam up to temp predictably in the morning with nice hot rads. The time to boil the water and heat all the rads was very predictable.
    And

    how long does the boiler run or how often does it cycle?
  • exqheat
    exqheat Member Posts: 185
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    I find the Honeywell 8000 w rf sensor good for all applications, including Exquisite Heat
    John Cockerill Exquisite Heat www.exqheat.com Precisions boiler control from indoor reset.
  • Paul3
    Paul3 Member Posts: 19
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    First, thanks to all posters - you have been a great source. My experience with Wifi thermostat:

    1880s single family house north of Boston. One and two pipe, single zone, steam system probably installed in the 1890's. Recently replaced 20 year old Weil McClain boiler. Regularly check, clean, or replace vents. System works very well.

    Installed a Honeywell RTH6500WF a few months ago. So far so good.
    • Needed to run a c-wire, which I connected directly to the transformer at the boiler.
    • Disabled the "Smart Response" feature, as after 30 years I know how long the system needs to heat the house.
    • See page 19 (Function 13) of the Honeywell manual on how to disable Smart
    • Also set the thermostat to be "System Type" Heat Only (see page 18 Function 1)

      One issue, as noted in other posts - when the Low Water Cut Off engages (happens rarely), the Honeywell thermostat goes blank. A bit disconcerting when it first happened. LWCO reengaged, and all thermostat settings were retained.

  • exqheat
    exqheat Member Posts: 185
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    your tstat is in series with lwco. rewire for constant power
    John Cockerill Exquisite Heat www.exqheat.com Precisions boiler control from indoor reset.