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    Thermostats (Honeywell and EcoBee) (13 Posts)

  • butlermog butlermog @ 8:22 AM
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    Thermostats (Honeywell and EcoBee)

    I currently have a Honeywell FocusPro 6000 thermostat which seems to do regular thermostat things well (schedule, detecting temperature, anticipating when the system should come on, etc.). Although I don't use much of that since I just set the temperature to 67 and hold.
    However, the cycles-per-hour setting and determining when to stop the call-for-heat seem to be all wrong.
    What a cycle looks like:
    T=00 - call for heat
    T+18 - system reaches 3oz pressure and vaporstat cuts out. radiators are all ~90% full which is where I would want them to stop getting steam on this vapor/orifice system.
    T+18 to T+25 - system pressure reduces to 1oz and vaporstat allows burner to fire again. 30 seconds off then 90 seconds on
    T+25 - call for heat satisfied
    T+60 - call for heat

    What seems odd to me is:
    1) the call-for-heat is exactly 25 minutes every time now. earlier in the season (before the cold got COLD) the call for heat was exactly 20 minutes. so is the Honeywell relying on time to kill the call-for-heat instead of the sensed temperature in the room?
    2) the second call-for-heat is exactly 60 minutes after the first call for heat. so is the Honeywell using the 1CPH as a rule instead of a maximum? I think the alternate explanation would be that the room loses all of the heat in the 35 minute off time and therefore needs to call-for-heat right when the CPH setting allows it to. In which case, setting CPH=2 might be an interesting test?

    I know that the newage 'smart' thermostats aren't really liked around here because none of them (Nest in particular) seem to have a CPH setting. However, I stumbled across the ecobee (https://www.ecobee.com/) thermostat that looks to be a bit more interesting because it looks as though it is programmable through a software API (Application Programming Interface). Has anyone - specifically any software engineers like myself looked into this ecobee and found anything interesting about it?

    What I think I want is a very dumb thermostat along with a control that stops the boiler from firing after being on for 18 minutes and then a control that allows another call for heat after 20 minutes of the radiators giving up heat. I know that MarkS (http://www.heatinghelp.com/forum-thread/129949/Temperature-based-cut-in-for-a-Vaporstat) has experimented with a time-delay relay after the vaporstat cuts out which might actually be the perfect solution for me.
    Anyone else using a similar but different solution?
    MarkS, if you're listening, are you still using your time-delay relay and is it successful like you thought it would be?
  • MarkS MarkS @ 12:38 PM
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    Time delay relay

    I had a modulating gas burner installed in the spring that adjusts the firing rate to maintain a pressure setpoint in the boiler, but the time-delay relay is still in place as a backup in case I ever need to run at a fixed firing rate.

    When the vaporstat-plus-relay was in more active service, it worked exactly as I'd hoped. When the pressure increased after all the radiators were full of steam, the vaporstat would activate the relay, which interrupted the low-voltage thermostat signal for 20 minutes. This gave the steam in the rads a chance to condense, and more often than not the call for heat would be satisfied by the time the timer expired. If the timer expired and there was still a call for heat, the boiler would re-fire. Tracking pressure shutdowns over the course of two seasons, I figure the control saved 100 gallons of oil or more.

    One change I made to the current setup is replacing the vaporstat with a much less expensive pressure switch from Dwyer. With the time-delay relay, I didn't need the cut-in capability of the vaporstat. And it's much easier to accurately adjust the trip point on the Dwyer.
    Homeowner, Royersford PA | 1890 one-pipe steam system | 3009 sf | 3 floors | 14 radiators | Utica SFE5200S boiler
    Midco LNB-250 Modulating Gas Burner | EcoSteam modulating controls | 70 to 300 MBH |
    607 sf EDR connected load | Operating pressure: 0.5 oz/in2
    Four main runs (insulated) totaling 135 ft in length | All Gorton vents on mains & rads |
    A Steam Odyssey | Odyssey 2 | Odyssey 2014 | A Steam Enthusiast's Outdoor Reset Control
  • SWEI SWEI @ 12:43 PM
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    Pressure Switch

    Was that a Mercoid D, or one of their other models?
  • MarkS MarkS @ 1:36 PM
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    Dwyer model

    Mine's an 1823-20 differential pressure switch, 3"-22" WC. I have it set to trip at 10" WC (about 6 oz). Repeatability is very good. You can find them pretty cheap on eBay.
    Homeowner, Royersford PA | 1890 one-pipe steam system | 3009 sf | 3 floors | 14 radiators | Utica SFE5200S boiler
    Midco LNB-250 Modulating Gas Burner | EcoSteam modulating controls | 70 to 300 MBH |
    607 sf EDR connected load | Operating pressure: 0.5 oz/in2
    Four main runs (insulated) totaling 135 ft in length | All Gorton vents on mains & rads |
    A Steam Odyssey | Odyssey 2 | Odyssey 2014 | A Steam Enthusiast's Outdoor Reset Control
  • SWEI SWEI @ 8:26 PM
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    Thanks!

    Nice price...
  • cdm cdm @ 12:09 PM
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    Time Delay Relay & Pressure Switch Option

    I read the post where a time delay relay and a pressure switch were used in place of a pressuretrol or vaporstat. It seems to me this would be ideal for my set-up, as my system runs at a very low steam pressure (less than 1 oz) and the radiators remain hot for long time after the boiler shuts off. The 20 minute dwell time (or an adjustable dwell time) allows for the radiators to additionally heat the room - This should reduce the short cycling time I see on very cold days. My question is - What is the make and model number for the timer used in this set-up?

    thanks -cd mulford-
  • MarkS MarkS @ 1:42 PM
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    Time Delay Relay

    Assuming you'll be switching 24 vac through pressure switch, use a Schneider Electric model TDR-SOXP-24. Mouser and Allied Electronics carry them.
    Homeowner, Royersford PA | 1890 one-pipe steam system | 3009 sf | 3 floors | 14 radiators | Utica SFE5200S boiler
    Midco LNB-250 Modulating Gas Burner | EcoSteam modulating controls | 70 to 300 MBH |
    607 sf EDR connected load | Operating pressure: 0.5 oz/in2
    Four main runs (insulated) totaling 135 ft in length | All Gorton vents on mains & rads |
    A Steam Odyssey | Odyssey 2 | Odyssey 2014 | A Steam Enthusiast's Outdoor Reset Control
  • cdm cdm @ 6:29 PM
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    Time Delay Relay and Pressure Switch Option

    Thanks for the time delay relay information.

    cd mulford
  • butlermog butlermog @ 7:01 PM
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    Programmable Logic Controller

    With a lot of help from another guy from The Wall I am working on a solution using a programmable logic controller from Teco (http://www.factorymation.com/SG2-10HR-A.html).
    There are many different units. The unit I am using is a bit different from the link above but the one in the link is a better unit because it has a keypad and screen.
    The programming is pretty simple. I am planning on starting with a very simple program that will only allow the burner to be on for X minutes at a time. I will then just use a very simple "dumb" thermostat. This way I will never produce too much steam for my radiators to condense and I will not have to worry about too much overshoot. Those two reasons are what I believe to be causing my boiler to run too long and therefore waste fuel.
    You can find some more posts about this from PMJ on The Wall. His program is much better than mine as it changes the value of X after a few cycles. So he starts out with a 5 minute burn and then waits to see if the thermostat is satisfied. If after a few of those short cycles it still isn't, he bumps it up to 8 minutes (then so on and so on).
    I am pretty excited about putting this solution in place even though I probably will have to wait until the fall since this heating season is mostly over for me. I think that I will make back the cost of the PLC in saved fuel in a few weeks.
  • cdm cdm @ 9:50 PM
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    Time Delay Relay and Pressure Switch Option

    Thanks for the information on the pressure switch and the time delay relay (both of which I have ordered). Any chance of a wiring diagram so I don't screw-up the installation?

    thanks -cd mulford
  • MarkS MarkS @ 7:55 AM
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    Wiring Diagram

    Here's a generic wiring diagram. You'll need to adapt it to your particular ignition control. For instance the Honeywell R7184 has a 24 VAC connection so you don't need a separate transformer.
    Homeowner, Royersford PA | 1890 one-pipe steam system | 3009 sf | 3 floors | 14 radiators | Utica SFE5200S boiler
    Midco LNB-250 Modulating Gas Burner | EcoSteam modulating controls | 70 to 300 MBH |
    607 sf EDR connected load | Operating pressure: 0.5 oz/in2
    Four main runs (insulated) totaling 135 ft in length | All Gorton vents on mains & rads |
    A Steam Odyssey | Odyssey 2 | Odyssey 2014 | A Steam Enthusiast's Outdoor Reset Control
  • cdm cdm @ 3:23 PM
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    Time Delay Relay and Pressure Switch Option

    Thanks for the wiring diagram - This will insure I wire this set-up properly.

    Thanks again -cd mulford-
  • saikosis saikosis @ 6:53 PM
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    ecobee

    I'm pretty sure that ecobee's optional ZigBee module is using the ZigBee chip made by my company. If that's true, there's a chance that some software I wrote is running on the thing. And if that's true, I definitely recommend you buy it!

    I started experimenting with building my own thermostat using an Arduino. My house is L-shaped with the boiler near the end of one leg and a bedroom at the end of the other leg. The thermostat is in a room with no radiator and sits almost directly above the boiler. The heat coming off the boiler and the uninsulated mains is enough to artificially keep the thermostat happy on mild days, leaving the other rooms a little cold. On really cold days, the lack of a radiator keeps the thermostat artificially unhappy. I'd like to add temperature sensors in the bedrooms and living spaces and intelligently figure out when to fire the boiler based on time and temperature. For example, during the day, I care about the living areas, but I care about the bedrooms at night. I also had the idea that knowing the temperature of the boiler water would help you know when to fire too. If the water is cold, you'll need to fire for awhile before you start making steam, so the thermostat could be smart and turn on a little earlier than normal. ChrisJ suggested adding outside sensors for temperature and wind speed would give you a lot of useful information for deciding when to fire too. There are a lot of variables. It's definitely an interesting problem.
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