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Aquastat 8124 and NEST

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I noticed my thermostat has been saying "delayed 2:xx minutes" during heating cycle. I counts down & shuts down without hitting desired temp. Then, it does a similar delay & countdown before trying again. After a few of these sequences, it usually hits the temp. I've had this Neat & boiler set up for years. I Googled this but I have a C wire and the internal battery voltage shows 3.95 (good). I have an aquastat even tho I don't use for domestic HW. My settings at 180, 140, 10. Grateful for feedback.

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  • pecmsg
    pecmsg Member Posts: 4,883
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    Why is it always a NEST stat that has problems?
    SuperTech
  • Jamie Hall
    Jamie Hall Member Posts: 23,438
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    That's almost certainly a Nest thing... good luck.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    SuperTech
  • RonC
    RonC Member Posts: 10
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    In an effort to zero-in on this behavior, I'm thinking I will put the old Honeywell thermo back on tomorrow. On what might be a separate issue, or just a question, the boiler does not start when I turn up the HI but does if I turn up the LO. I thought the boiler would maintain hotter water and only circulate it during a call for heat. My boiler always starts when there's a call for heat & usually shuts down once it hits set temp.  
  • HVACNUT
    HVACNUT Member Posts: 5,863
    edited January 2022
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    The L8124 will always maintain the low limit setting. It only goes to high limit on a heat demand.
    RonC
  • RonC
    RonC Member Posts: 10
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    Thanks, I thought it reserved the LO setting for domestic HW and disallowed circulator until temp was higher than LO + DIFF ? In this scenario, with a call for heat, my boiler would always run, but the circulator wouldn't be allowed to run until temp was more than LO+DIFF. Is what I'm saying still true ? I can't imagine the NEST is smart enough to predict how long before circulator will be delayed. No idea why NEST is doing this "delayed"  stuff. 
  • SuperTech
    SuperTech Member Posts: 2,186
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    It's doing that behavior because it's a POS. Ditch the Nest, there's no benefit to having one on a boiler. I'm sure if you put the Honeywell thermostat back on the wall you won't have any problems. 
    SteamBoiler
  • HVACNUT
    HVACNUT Member Posts: 5,863
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    First, if the Nest wiring is only 2 wires, R-W to T-T on the aquastat, then it needs to be rewired with a separate transformer and isolation relay. It doesn't matter if "it's been fine for years".

    And yes, during a heat demand, the L8124 will work off the high limit and cut power to C1 if the boiler temperature drops below the low limit setting. With no heat demand, it'll cycle off the low limit, less differential. 
    RonC
  • RonC
    RonC Member Posts: 10
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    We like to be able to adjust the heat down when we're away & remotely put it back up a few hrs before we return, to a warm house. My NEAT is essentially just the two wires but somehow I modified to have a C wire. I do shut system off in summer and still like to see a functioning thermostat .. for window A/C. Any NEST experts out there ?
    SteamBoiler
  • Jamie Hall
    Jamie Hall Member Posts: 23,438
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    You are looking for a Nest expert? Difficult. The fundamental problem is that Nests were designed to work with standard forced air systems of recent construction. For that they work well, and the folks at Apple can help. They were never designed to work with any form of high mass system -- hot water, steam, radiant, nor were they designed to handle the variety of control systems and wiring which are used for those systems. There are some work arounds for those systems, but they are particular to the specific installation (virtually every single one is different) and thus, without boots on the ground and a very clever individual it is impossible to be sure any given work around will work on any given system.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Ironman
  • SteamBoiler
    SteamBoiler Member Posts: 90
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    RonC said:

    I noticed my thermostat has been saying "delayed 2:xx minutes" during heating cycle. I counts down & shuts down without hitting desired temp. Then, it does a similar delay & countdown before trying again. After a few of these sequences, it usually hits the temp. I've had this Neat & boiler set up for years. I Googled this but I have a C wire and the internal battery voltage shows 3.95 (good). I have an aquastat even tho I don't use for domestic HW. My settings at 180, 140, 10. Grateful for feedback.

    I had the exact same problem with my new Nest - on a steam boiler - which was working fine for a few weeks but suddenly started with the "Delayed for 3:00" with a countdown a couple days back. On googling it seemed related to lack of C wire, but just like you, I have a C wire installed, battery voltage was 3.95V and all technical info voltages were between 32V and 38V and Iin=200mA (solid on spec). Nest first level support was no help and wanted to blame my wiring and HVAC and to call in a Nest Pro. I told them I would just buy an Ecobee for the same price as a Nest Pro. I ended up resetting my Nest to factory settings and it has been OK in the last couple days. Obviously if anything were wrong with the HVAC transformer board it should have shown up immediately.

    Someone on Reddit also had the same issue at about the same time, I would wager it is a Nest back end issue.
    RonC
  • Peter_26
    Peter_26 Member Posts: 129
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    Try turning the True Radiant function off. I have had the countdown delay when I first got the Nest like 3 years ago and after turning it off it did not display the message. It's in the Nest Sense settings.

    I recently had a delayed heating message and after observing the boiler I noticed that it had hit high limit. I think it that scenario the Nest gives the system a cool down period before it restarts the equipment even though it hasn't hit the target temp. After further investigation it turned out that transformer for the Honeywell zone valve head that controls the basement loop died and was causing my oversized boiler to hit high limit. Maybe you have another issue like I did and it has nothing to do with the Nest.

    Also, I check the Nest software version every now and then, I have had instances in the past that when they update the software version they override your settings to default and sometimes some of those features like True Radiant are set to on. I have to admit that like many of forum members have pointed out it has no place for systems that they were really never designed for.

    SteamBoilerRonC
  • Ironman
    Ironman Member Posts: 7,379
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    RonC said:
    We like to be able to adjust the heat down when we're away & remotely put it back up a few hrs before we return, to a warm house. My NEAT is essentially just the two wires but somehow I modified to have a C wire. I do shut system off in summer and still like to see a functioning thermostat .. for window A/C. Any NEST experts out there ?
    Get a Honeywell Lyric which was designed by heating engineers instead of the Nest which was designed by IT geeks.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    SteamBoilerSTEVEusaPASuperTech
  • SteamBoiler
    SteamBoiler Member Posts: 90
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    Peter_26 said:

    Try turning the True Radiant function off. I have had the countdown delay when I first got the Nest like 3 years ago and after turning it off it did not display the message. It's in the Nest Sense settings.

    Not OP but I have a Weil McLain steam boiler and recently installed Nest and relatively happy with it. It replaced a 2 wire mercury thermostat that I believe was just short cycling my boiler - basement was warm but home was not. I have all the smart settings turned off except for True Radiant. When True Radiant is off, does it run long heat calls till it overshoots the set point by a bit? Right now, after about a week of learning with True Radiant, it turns off heat calls a little below the setpoint and lets the radiators coast the home to a little above setpoint. If I could do an Ecobee and mandate minimum call time I would be really happy.
    Peter_26 said:

    I recently had a delayed heating message and after observing the boiler I noticed that it had hit high limit. I think it that scenario the Nest gives the system a cool down period before it restarts the equipment even though it hasn't hit the target temp. After further investigation it turned out that transformer for the Honeywell zone valve head that controls the basement loop died and was causing my oversized boiler to hit high limit. Maybe you have another issue like I did and it has nothing to do with the Nest.

    Did you have Nest connected to the same transformer as the zone valve head, or a different transfomer? I have my Nest connected to the Weil McLain transformer and it looks like the pressuretrol is connected directly to the boiler firing controls so when my boiler hits high pressure limit it would turn off but I believe Nest likely wouldn't know about it and would keep calling for heat.

    I apologize for the multiple questions but on this forum it is difficult to get useful information about Nest. I love the information on heat call duration. Short of writing your own logger you can't get that information. So far I am averaging the same gas usage as I did last year on the mercury thermostat and the home is much warmer.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,622
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    We need a full t :) ime forum for Nest issues
    Peter_26SuperTech
  • SteamBoiler
    SteamBoiler Member Posts: 90
    edited January 2022
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    Ironman said:


    Get a Honeywell Lyric which was designed by heating engineers instead of the Nest which was designed by IT geeks.

    On their own website the Lyric is sitting at an average rating of 1.7/5.

    Embarrassing.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
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    On their own website the Lyric is sitting at an average rating of 1.7/5.

    Embarrassing.

    Yeah if it's online, it must be true. All that tells me is that Lyric allows all ratings. And if they don't ask for a rating usually people only come on to complain.
    Of all the wifi t'stat questions/complaints/troubles on this site, I can't recall even seeing a problem with a Lyric. Nest, nothing but trouble. Sometimes right away, sometimes later. But almost always eventually.

    There was an error rendering this rich post.

    IronmanSuperTech
  • Jamie Hall
    Jamie Hall Member Posts: 23,438
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    Ironman said:


    Get a Honeywell Lyric which was designed by heating engineers instead of the Nest which was designed by IT geeks.

    On their own website the Lyric is sitting at an average rating of 1.7/5.

    Embarrassing.
    All of the ratings, of course, from eminently qualified critics who have carefully analysed the equipment. Right. And by the way, I have a 10% share in a bridge in New York. Excellent investment, but I need the money and will sell it to you on good terms.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    IronmanSuperTechCanucker
  • RonC
    RonC Member Posts: 10
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    Thanks guys .. I did reset to factory defaults and "reinstalled" with everything the same as before, radiant off (for the time being). So far it hasn't misbehaved but time will tell. Mine does overshoot a few degrees so by the time it calls for heat again, it takes 45 minutes .. water needs to be heated and circulated which brings me back to another question .. I can't easily tell when circulator is on .. when is it supposed to be in terms of water temp ? Obviously during a call for HT. When water is above LO only, or above LO-minus-DIFF ? Lastly, my settings are HI 180, LO 140, DIFF 10. I would I'd get a quicker response if I increased the LO to keep water in hotter. Appreciate it the input.
  • Ironman
    Ironman Member Posts: 7,379
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    You’re wasting a lot of fuel keeping the boiler hot if you’re not using the domestic coil. I’d set the LO limit down to 100* which would keep it a warm start. And ditch the Nest; it’s not saving you anything.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    SuperTech
  • RonC
    RonC Member Posts: 10
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    Not using NEST to save, just to adjust temp remotely. I prefer to turn off all the so-called smart features but some you can't. NEST idea of savings is to overshoot and run less often. I'd rather dial in a little more accuracy. 
    I may try Tru Radiant to reduce overshoot if it behaves ok (without delayed BS).

    I'm okay with lowering water temp a little (maybe 120) but, my understanding is you want hot water in the radiators so that burst of heat will rise and travel across room (convection currents).

    So, what water temp settings allow the circulator run ?
  • SteamBoiler
    SteamBoiler Member Posts: 90
    edited January 2022
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    RonC said:

    Thanks guys .. I did reset to factory defaults and "reinstalled" with everything the same as before, radiant off (for the time being). So far it hasn't misbehaved but time will tell. Mine does overshoot a few degrees so by the time it calls for heat again, it takes 45 minutes .. water needs to be heated and circulated which brings me back to another question .. I can't easily tell when circulator is on .. when is it supposed to be in terms of water temp ? Obviously during a call for HT. When water is above LO only, or above LO-minus-DIFF ? Lastly, my settings are HI 180, LO 140, DIFF 10. I would I'd get a quicker response if I increased the LO to keep water in hotter. Appreciate it the input.

    After I got the "Delayed for 3:00" minutes messages and couldn't figure out the issue, I reset mine to factory defaults and reset from scratch (I do have Radiant on but preset=0 and all other features off) and it has been behaving OK as well. I am sorry I am not familiar with the Aquastat but FWIW I suggest opening out the limits on anything that could cause Nest to misbehave. In my system the thermostat is physically and electrically connected downstream (in series) with a low water cut off and if the water is running low and it chatters then Nest will lose power and run off battery and may behave unpredictably; so I am trying to keep water topped up every week. Additionally, I realized that if I hit the high limit on my pressuretrol the boiler will cut off - which Nest doesn't know anything about - so it may keep calling for heat and might be causing the "Delayed" messages. So I set the pressuretrol add-in to 1.5psi (it was originally at 1.5 but following the advice on this site I had set it to 1). The heating calls now seem to be longer than what they were previous to the reset (25-30 minutes every 90 minutes or so but it is also colder now) so it is possible that my boiler had been cutting out on pressure. So far so good, I am trying to keep things from going non-linear.
  • SuperTech
    SuperTech Member Posts: 2,186
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    I don't understand why anyone would deal with the difficulties and aggravation that these lousy Nest thermostats cause. Do you want to be able to check your thermostats with your phone? There are dozens of better options than the Nest. I see nothing but problems with them. Had an emergency call today, the Nest inexplicably started bringing on the A/C with the furnace. I replaced it with a Honeywell Focus Pro IAQ and smashed the Nest afterwards. Wake up everyone! It's not a good product. 
    IronmanpecmsgSTEVEusaPASteamBoiler
  • RonC
    RonC Member Posts: 10
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    As prev ..  reset to factory, everything off including Tru Radiant. Seems fine now but this morning it missed the temp change by an hour ! Perhaps it's relearning and it was like 1°F. It was an effort to bring house from 64 to 68 so this brings me back again (3rd time) to .. during what temps is circulator allowed to run with my 8124 aquastat set at HI180, LO140, DIFF10 ? Would the answer be 130 & up, 150 & up, or something else ? Instead of bashing NEST, or after you do so, please try to answer the question(s) ?
    SteamBoiler
  • Jamie Hall
    Jamie Hall Member Posts: 23,438
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    At the very least the boiler -- or whatever is controlled by the aquastat (it may not be the boiler) -- should be live between the low and the high settings.

    I'm not going to bash the Nest. The fact that I don't like them and I have yet to see one which works well with anything but forced air isn't a bash, it's just a statement of observation.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    RonC
  • pecmsg
    pecmsg Member Posts: 4,883
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    SuperTech said:

    I don't understand why anyone would deal with the difficulties and aggravation that these lousy Nest thermostats cause. Do you want to be able to check your thermostats with your phone? There are dozens of better options than the Nest. I see nothing but problems with them. Had an emergency call today, the Nest inexplicably started bringing on the A/C with the furnace. I replaced it with a Honeywell Focus Pro IAQ and smashed the Nest afterwards. Wake up everyone! It's not a good product. 

    They do make a good Hockey Puck or Skeet target :)
    SuperTech
  • RonC
    RonC Member Posts: 10
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    I'm not especially fond of NEST products right now either, but my question is about Aquastat 8124 settings and the range if operation allowed for the circulator. Anyone know anything about that ? 
    SteamBoiler
  • Ironman
    Ironman Member Posts: 7,379
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    Ron, the aquastat will energize the pump when there’s a call from the stat.

    It appears that you’re trying to taylor the system to operate in accordance with what the stat is doing which is exactly backwards to the proper approach.

    The boiler was designed by knowledgeable heating engineers to operate the way it does. Any ancillary component (like a thermostat) must accommodate the boiler’s design - which is pretty standard.

    Because you’re not using the domestic coil, you don’t need the LO limit function and it could actually be turned off. We sometimes recommend leaving it at 100* to make the boiler fire off more reliably and protect it from thermal shock. If you leave it at 140*, you’re wasting a lot of energy from standby losses up the chimney - probably about 30% of your fuel usage. To do that to try and make your system work with a junk stat the way that you perceive it should makes no sense to me.

    As mentioned many times, there are other WiFi stats that will work just fine with your system without all the control gymnastics.

    Please ditch that thing and get a good one.

    We’re trying to help you.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    STEVEusaPASuperTech
  • RonC
    RonC Member Posts: 10
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    Appreciate the advice but I am not currently concerned about the thermostat. I know the aquastat used with my boiler was originally used with domestic HW and the LO setting would prevent circulator from running the temp any lower. So what I'm trying to zero in in on my is .. with my LO at 140 (for now), and the DIFF at 10, at what temp will my circulator NOT run ...150, 140, or 130 ? I get what you are saying about keeping water hot (at 140) and not opposed to lowering it and heating the water further while it circulates. 
  • Jamie Hall
    Jamie Hall Member Posts: 23,438
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    Do you, in fact, have the manual for that aquastat? I hate to even ask, but have you read it? Page 10 has an excellent description of what contacts open and close at what temperatures relative to the various settings. It answers all of your questions about the aquastat.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • RonC
    RonC Member Posts: 10
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    I found the manual (on line) and found my answer, thanks. With LO at 140 and DIFF at 10, circulator runs unless temp falls to 130. If that happens it'll run again when water gets back up to 140. DIFF is also used with HI so boiler shuts down at 180, starts again when temp drops to 170. Very interesting. I revised my LO to 130 and will prob go lower yet after this cold snap. Thank You All.
    SuperTech