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Storage and programable thermostats

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Coal Reaper, Oct 12, 2013.

  1. Coal Reaper

    Coal Reaper Minister of Fire

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    Better to maintain temps in house or allow temp to drop when away from home and/or sleeping?
    I have two zones on each floor, fin tube baseboard, 1000gal pressurized storage, set point circ returning water to storage at 120*F. Circ is bumble bee, ecm motor with four speeds. We are not really into heating season yet but i turned two zones on the other night. 155* supply and pump running at lowest speed was returning water at 140*. We could say that the house loop is over pumped but its only a 007 and i am not changing it. So i am wondering if i maintain temp in the house is it better to have the system cycle more frequently for shorter periods of time? Or should i not worry about returning water back to storage thats not down to my set point? Also supply temp most of the time is 180 +\- 10*. And water does go through the oil burner just before hitting the close tee to go back to storage.

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  2. Nofossil

    Nofossil Moderator Emeritus

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    If you have enough baseboard to raise the house temp reasonably quickly, you'll gain some efficiency by setting back the thermostats when you don't need the house to be warm. The cooler the house, the less it loses to outside.

    It seems like your second question is about how to avoid returning water that's still pretty hot to your storage. That's a really good question. Ideally, you could take that return water from the baseboards and run it through a radiant zone or something to get it cooler before returning to storage.

    I've thought about loading up the baseboard zone(s) with hot water, then recirculating it until it's cool, then returning to storage. In my case that would take some work, so I haven't done it. Fun to think about, though.
  3. Coal Reaper

    Coal Reaper Minister of Fire

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    The zone i am most interested in setting back does take a bit of time to heat up. It encompasses the dining room, tiled kitchen, and cathedral cieling livingroom with balcony to master bedroom which also has a cathedral cieling. I plan to close this up one day as all the heat just coasts up through there and cold air pours down the stairs in the dining room.
    Now i am talking about 68* during the day and 62* at night. How much difference is that really going to make with regards to heat loss?
    Adding a radient zone is something i likely will try in the coming years. Basement has drop cieling under sun room and dining room, open cieling in mechanical room under living room and the only problem would be the sheetrocked garage under kitchen. Is it feasable to just extend the zones themselves? I have zone valves with 007 feeding all. I also dont know if i should be concerned about the wood floors.
    Recirculating until cool was the idea behind the set point pump. It works really well. The exception is when i supply really hot water with only one zone open. The pump runs on its lowest setting but it still moves some water that is hotter than the setpoint. Claims 6gpm but that would mean 3' head loss going by tacos curve chart. Thats on an effective 400' round trip so it aint right. That display goes off of pump speed, nothing to do with head loss other that impeller resistance. Still, its probably low enough flow that i shouldnt be concerned. But yeah fun to think about! This BS keeps me up at night...
  4. avc8130

    avc8130 Minister of Fire

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    I think one of the concerns with hot water baseboards you might run into is uneven heat on the zones.

    The problem with large delta T and baseboards is that the loops usually service more than one "room". So you bring 160F water to the beginning of the run and it heats that room "well". If you strive for 120F return, the end of the run "room" will be getting significantly less heat than the beginning.

    Depending on where the thermostat is will determine how drastic this is.

    I wouldn't worry too much about the ceilings/balcony arrangement, unless it is overheating your upstairs. Otherwise, your upstairs zones just won't run as much as your lower.

    ac
  5. Coal Reaper

    Coal Reaper Minister of Fire

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    Very open floor plan and tstat is right in the center of the whole show. There is walkthrough between kitchen and dining room and both of those rooms are open the the length of living room.
    I agree about ceilings/balcony but this drastically extends the recovery time to bring up temps.
    This morning saw 180* supply and 172 return with just that one zone running. That zone is 42' baseboard plus a toe kick heater. I am going to try dropping the set point to 100* so it backs off sooner. Will have to see how this works at lower supply temps tho.
  6. __dan

    __dan Feeling the Heat

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    I don't know enough about your setup to know exactly what applies.

    If you are already setup with a primary secondary pumped loop, an outdoor reset control may do one of the things you are talking about, recircing the supply water, lowering the return water, and adding a smaller quantity of hot supply to the secondary loop. It is likely an OAT reset control would require some plumbing change, a VS pumped injection loop between the primary and secondary loop or a three way valve. It's usually a costly extra, but the fuel is usually costly also. I don't understand what the Bumblebee is doing in relation to your system.

    Electronic programmable stats have PI or PID control, electronic learning and anticipation. If you are upgrading from a snap action or mechanical stat with a differential, the differential causes to stat to overheat and underheat a few degrees in the differential range. The PID control will do a timed fire or timed pump on cycle, and learn how much heat is necessary to maintain space temp +- 0.5 deg. For example, the electronic stat will call heat for 10 - 15 minutes and wait to see how well that works, constantly adjusting the on / off cycling, PWM, to eliminate the under and over, the hunting, about the setpoint. PI control compared to operating a stat with a differential will give you more evenness of heat and some fuel savings.

    Most applications, night setback is good in theory but beyond most homeowners ambition to make work correctly, programming of the stat. The stat normally is finished recovering from setback when the occupied time comes. It does not begin to recover when the occupied time comes. OAT reset and PI control stats work in auto continuously with no intervention, no adjusting, necessary by the homeowner.

    I you have old style mechanical stats now, programmable PI stats are a cheap upgrade. Nothing fancy beyond the electronic PI control is usually necessary.
  7. __dan

    __dan Feeling the Heat

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    Just saw your install photos in your other thread. Wow, that's a beautiful looking install.

    So it looks like a boiler in an outbuilding, so you may have a single high temp loop to the house for heat and DHW. Is that where the bumblebee is, between the outbuilding and the house? Set to run fixed delta T?

    In almost every application I would recommend OAT reset of the heat load loop water, but it is an extra expense for the customer, so it's something most customer's do without. If that's your install trade labor, I'm impressed. The OAT reset may mean adding another 007 and a Tekmar controller, or moving your existing 007 and putting another VS ECM pump (fixed delta T ?) in front of the zone loads. The Tekmar controller is made to work with a standard 007. AFAIK, OAT reset ECM circs are not on the market yet, but will be in the future.
  8. avc8130

    avc8130 Minister of Fire

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    Yeah, that is his setup.

    ac
  9. Coal Reaper

    Coal Reaper Minister of Fire

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    Except no delta T. The bumble bee returns water to storage at set point (changed it to 100* today) indifferent of the supply temp. Its ecm motor so it cranks until it sees that temp and then it backs off pump speed. Runs at 9-11 watts at lowest speed. Even at lowest speed after everything is warmed up it is returning water greater than the set point tho.
  10. arbutus

    arbutus Feeling the Heat

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    Another option could be to use Taco i series 3 way mixing valve with outdoor reset.
    Depending on the cost of your thermostat, relay, enclosure, etc it may be a wash.
  11. Coal Reaper

    Coal Reaper Minister of Fire

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    I did do everything myself. It was my first time sweating copper bigger than 1/2", let alone installing a remote boiler with storage. I spent a great deal of time researching. In hindsight perhaps i should have put in an outdoor reset but was uneducated about them at the time. At this point there is no more available funding to mess around with anything else until the loan from boiler is paid off. Hey, those payments are cheaper than my oil bill was! Now i am just restricted to making non-monetary adjustments to current system. It is performing well and i am very happy.
  12. ewdudley

    ewdudley Minister of Fire

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    My setup is pretty similar except it uses a stratified hydraulic separator as opposed to a primary-secondary. Either way return temperature to storage can (in theory) be controlled independently from the load circuits.

    If the Taco HEC-2 continues to run even after return temperature reaches setpoint then either it's not programmed correctly or (more likely) there's a design defect on Taco's part that won't let you program it to work right. Simplest would probably be to strap on a $50 aquastat (e.g., http://tinyurl.com/m4jebp5) upstream of the Twin Tee that would disable the HEC-2 when return to storage is too warm.

    Or just wait until you get deeper into the heating season and probably it will be able to run constantly (when there's a call for heat) without exceeding the desired return temperature.

    As for outdoor temperature reset, I've found that poor-man's reset works just fine. Just keep doing what you're doing and adjust the return temperature to storage every week or so according to what works and your best guess of the upcoming weather.

    To answer the original question, I would say don't bother trying to affect return temperature to storage by adjusting programmable thermostat strategies, just attack the return temperature to storage problem head on.
    Last edited: Oct 13, 2013
  13. avc8130

    avc8130 Minister of Fire

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    Coal,

    What is the temperature difference at each end of your underground piping? Other than pumping the water extra, are you losing a bunch heat you are concerned about?

    ac
  14. Coal Reaper

    Coal Reaper Minister of Fire

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    Hec2 continues to run when temps are above setpoint, but at its lowest speed 1. I am thinking this is design intent to keep some flow for it to respond. Thinking about it, it should be minimal flow as it uses as little as 9 watts in this state. I am not even too worried about this.
    I did consider aquastat. The problem is that the hec2 cranks at full speed when it first gets powered up. I guess they do this strong flow to establish temperature and then see where its at. I wouldnt want it to turn off and then back on at full power in the middle of a call for heat when things were already at operating temp. That could unnecessarily send as much as 36 gallons hot water back to storage before it backs off on power.
    Thanks for your opinion on original question. My thought was that this is best for a storage situation whereas when i was burning oil it was better to turn tstats down when not needed.
  15. ewdudley

    ewdudley Minister of Fire

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    What a disappointment that pump has turned out to be, although you've really got to hand it to the marketing department, the cute name and adorable color scheme are just fabulous.

    Turn it on and it does exactly the wrong thing (in this application). It just seems like their whole 'design philosophy' was dreamed up by a bunch of foundry-men thinking all baseboard, all the time.
  16. Coal Reaper

    Coal Reaper Minister of Fire

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    I have been meaning to take the ir gun to the pipes. I really dont know. When i say supply and return temps i am looking at gauge on storage tank top and gauge on oil burner which is right before close tee. Not too concerned about losing heat underground. It is what it is right? But the cooler i can send water back to storage the better stratification i will get. The less hot the oil boiler gets the less heat i lose up that flu.
    I have been lowering the set point temp to see what i can get away with. At 140* the pump wouldnt even dial back before the DHW was satisfied but i know i gotta be careful going too low. Now say if the wife were to run out of hot water while washing dishes or something...well, that would put me in a not so good situation...
  17. Coal Reaper

    Coal Reaper Minister of Fire

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    I
    I disagree and perhaps i am explaining incorrectly. I am very happy this hec2. At first i questioned if it will move enough btus but it is looking like it will. I dont mind the three minute startup at speed four. This clears my 150' run from barn and the cold water from that zone out of loop. It does continue to run at my setpoint but at speed 1. It is pulling a mere 9 watts on speed one. I need to look at the pump curve again but with 400' effective feet in 1-1/4" pex there is not much flow. I know several guys wanted it reverse acting for return water protection. For my application it seems to be working quite well. I was playing with some numbers the other day and on paper my little bumble bee can deliver 250,000 btus/hr from storage for a sustained 2.7 hours. I think this was using 80* deltaT. The true test will be this winter when the house sees some serious heat loss. Why do you think its a disappointment?
  18. __dan

    __dan Feeling the Heat

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    When the Bumblebee has power, is on, there will be a default minimum speed. It will not turn itself off or run slower than the default minimum. This is the behaviour I would expect but I would have to confirm that with Taco.

    If the Bumblebee is always on, you would want to power the circ only with a call for heat, slaved with a relay in parallel with the load circs. No call for heat, the Bumblebee should be off, you would have to cut power to the Bumblebee. I'm assuming you are sensing the return temp from the house for setpoint control.
  19. Coal Reaper

    Coal Reaper Minister of Fire

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    Affirmative on all accounts.
  20. Bob Rohr

    Bob Rohr Minister of Fire

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    Early setback t-stats claimed un-beliveable fuel savings with deep setback. After ASHRAE and Brookhaven Labs and a few others actually did some long term studies I believe the consensus was maybe a 5F max setback.

    Remember unless the partition walls, and doors between rooms are well insulated it's almost impossible to do room by room setback. Heat goes to cold, always. The wider the delta t the more the transfer.

    I got an Ecobee wifi stat for Christmas last year. An amazing control. You can view and adjust from anywhere, via your smart phone. It displays temperature and humidity and outside temp with an additional sensor. It goes beyond ODR by logging onto multiple weather stations and watches approaching conditions. So it can adjust before the weather or cold temperatures are sensed at the ODR control.

    It can call, e-mail, or text you in the event of a problem, as well as a service person. Multiple stats can be viewed on one screen at your login portal. Have a 20 year old help with the programing :)

    I imagine the Nest and Honeywell, etc have similiar wifi stats now. I see Nest has a rather unique CO detector coming out. CO detectors are a must on every fossil fueled installation if it is within the living envelop.
  21. Bob Rohr

    Bob Rohr Minister of Fire

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    For as long as it took them to offer a small ECM smart pump, I think they missed some basic features.

    A reverse or changeable Delta T should have been on board. Seems like a contractor focus group would have insisted on that choice?

    It is tricky to program. Hold 3 buttons for so many seconds, then two, then toggle around, seems cumbersome?

    The motor cannot be rotated in the volute, so on vertical installations you need to turn your head to read and program.

    Mine makes a whirling sound on the high fixed speed, all other circs, even Tacos, are virtually silent.

    It being aggressively marked as superior to delta P, for most applications. At least until they develop a delta P version :)
  22. ewdudley

    ewdudley Minister of Fire

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    The pump was a disappointment from the get-go when it existed only as vaporware for literally years.

    Now that it actually exists, if the job of the pump is to maintain a setpoint by adjusting flow, then I am disappointed if the pump continues to run without regard to the temperature. Avoiding this defect is accomplished with a standard feature called "integrate-off" that is specified with a programmable kelvin-seconds limit.

    Also if the temperature is already above setpoint when the pump is activated then I would be disappointed if the pump runs at full blast for some magic amount of time just because some random programmer punted, or worse yet, because some engineer sincerely believed this would be correct or at least harmless behavior in all cases.

    All they needed was a "please-believe-the-sensor-and-do-not-presume-to-do-anything-clever-on-my-behalf" setting, but they failed to consider that there could be actual situations where the sensor reading is actually true. Stranger things have happened.

    And as you mention, I am of course disappointed that reverse-acting modes were not included, especially since their previous variable speed temperature controlled pump did.

    And when they promised to deliver a reverse-acting mode in time for this heating season, and then failed to deliver, it is yet another disappointment.

    On the supply side I'm sticking with my $75 008, a $35 PID controller, and a $12 relay. The solution may burn a couple dollars a year more electricity, but at least it can maintain setpoint and knows enough to shut itself off for hours on end if that is what correct behavior implies.

    On the load side my single lonely Wilo Stratos keeps one or ten zones at setpoint with its pressure setting at its lowest position; no sensors, no patronizing hand-waving "delta T design philosophy" nonsense, no nothing, just more zones more flow, less zones less flow, no zones no flow.
    Last edited: Oct 14, 2013
    woodsmaster likes this.
  23. Coal Reaper

    Coal Reaper Minister of Fire

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    I see what you guys are saying. It is magnitudes louder than the 007 i have, but much quieter than the oil burner it is located near. After hearing that oil burner for a year, i will gladly take the noise of this circ. i do think that threeminute speed 4 crank on startup is unnecessary. the biggest complaint i have is that it is a real PITA to program!
  24. Coal Reaper

    Coal Reaper Minister of Fire

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    best i can tell is 179-176. How does this compare to pre-insulated pipe? My run is about 150' one way. The ir gun i have jumps around quite a bit, not even worth noting the decimal point. I think i have a temp probe for my fluke meter i will have to try to find.
  25. avc8130

    avc8130 Minister of Fire

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    I assume supply at the tank is 179 and it is 176 by the time it gets to the close tee?

    Most pre-insulated CLAIMS 1F/100' at 5gpm.

    ac

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