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  1. barnartist

    barnartist Minister of Fire

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    Loc:
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    Curious how everyone handled the wind and cold. I sure notice a surge in btu usage. Wondering too if you guys with your wood boilers inside your house notice a big difference, or just a small one on windy days. I realize its nothing new with heat losses around the house.
    My Dad's havin baby calves in this sh^&%$t. Wish they could feel some gasifi'in heat. Can't wait for spring.

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  2. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    We built our house to capture the view west . . . a/k/a "holy crap it sure is windy :wow: " We didn't insulate that wall anything more than standard, which is one thing I'd do differently if given the oportunity. No question that it's easier to heat when it's colder than when it's windy.
  3. deerhuntrer

    deerhuntrer New Member

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    Loc:
    Mountains of Maine
    Its extremely windy here today with snow blowing all over the darn place. I definatley use more wood on a windy day (wind gusts around 40-50 MPH) The bad part is the blowing snow. The snow blows up into the grill of the furnace and freezes and creates a ice jam on the damper, thus it stays open, and thus it boils over. I used my kids Red Flyer wagon to cover the opening so the snow would blow in as much. I did use a cardboard box duct taped on but, it blew off. This is the only negative thing I have experienced with my outside boiler. It happens whenever we get drifting snow.
  4. pbvermont

    pbvermont Member

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    this is a very good point. The concept of "windchill "has occured to the weather scientists in regards to human bodies, but has anyone (besides barnartist) thought about windchill in regards to heated bldgs?
    They now use the technology of outdoor reset with boilers (a thermistor reads the outside temperature and gives input to the boiler, in addition to the input of the inside thermistat). Why don't they also have a sensor that reads outside wind/air movement that also gives input to the boiler? Esp. in places that have high exposure to the wind.
    Nofossil...? An opportunity. Charts. Graphs. Galore!
  5. Eric Johnson

    Eric Johnson Mod Emeritus

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    My old house can get drafty in places when the wind blows hard. I just turn up the heat and it's not a problem, but it does have an impact above and beyond the ambient outside temps.
  6. barnartist

    barnartist Minister of Fire

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    Loc:
    Jerusalem, Ohio;
    For the record I can keep my 3200 sq house at 75f even at yesterdays iceburg. I just hear my furnace fan run forever. I do wish I could hand over the money for the difference in better insulated walls and windows.
  7. Nofossil

    Nofossil Moderator Emeritus

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    I've actually though about this in a different context. I have a web based control panel for myself and my family. Instead of the detailed technical data, it answers the more practical questions - do I need to build a fire yet? Do I need to add wood? Is there enough hot water?

    I'd like to make it smarter so that it can tell you how many hours of heating capacity is left in the storage. In order to do that, I'd need to know the forecast values for temp, wind speed and direction, and cloud cover. I'm playing with a script that extracts that information from a weather forecast web site.

    Interestingly, the current conditions aren't of much use in this case, though I'd like to log them for analysis.
  8. pbvermont

    pbvermont Member

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    Good going. I had a sneaking suspicion that you'd be on top of this opportunity.
  9. Eric Johnson

    Eric Johnson Mod Emeritus

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    Can you factor in the reality that the weather forecast is often wrong, nofossil?
  10. Nofossil

    Nofossil Moderator Emeritus

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    I suppose I could log the forecast and the actuals, and at least be able to analyze how wrong the forecasts are ;-)

    When I have a fire going, it would be interesting to have the system advise me when a few more logs would give me enough heat to allow me to skip the next day, based on best available data. Perhaps I could add logic that says "Another 40 pounds of wood will give you a 75% chance of skipping a fire tomorrow with a WAF of 80% or higher". That presupposes modeling the function that correlates WAF with room temperature. This unfortunately runs afoul of both Godel's incompleteness theorem as well as Heisenberg's uncertaintly principle. Clearly, both these men were married, and their groundbreaking work can be summarized as follows: "There's no way we can know what women want, and if we try to figure it out, we'll always be wrong".
  11. slowzuki

    slowzuki Feeling the Heat

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    Your house starts losing heat everywhere when the wind blows. Two things happen, one is your air changes increase from the difference in pressure on the sides and top of the house. Two is your boundary layer, the thin layer of air that sort of sticks to the outside of your house is stripped away causing more rapid conduction away.

    Unlike your skin, a house doesn't have evaporation so the human windchill charts don't work right.
  12. pbvermont

    pbvermont Member

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    I'm curious about what the WAF data-input sensor might look like?
  13. Eric Johnson

    Eric Johnson Mod Emeritus

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    Ears and eyes for the most part. On (hopefully rare) occasion, the data takes the form of airborne projectiles. Denial of access can be another indicator of a low WAF.
  14. barnartist

    barnartist Minister of Fire

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    Loc:
    Jerusalem, Ohio;
    Please include WAF extended shower periods as well. And WAF turn up the heat when your not looking.
    Why not buy one of those home weather stations, I think you can connect them to your computer, have that current data, then type in what is being predicted, and have your puter spit out: Please add 21.46353 pounds of wood.
  15. sled_mack

    sled_mack New Member

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    Indoor reset can offset for conditions like wind.

    My thermostats are PI contolled, with a 20 minute cycle time. My PLC monitors a few key zones. If those zones are calling for heat more than 75%, I add a bias to the outdoor reset calc. That bias is 0 to 15 deg.

    It works like a champ. I can keep the outdoor reset curve low, so that I'm not using too hot of water temps on sunny days or days with low wind. Even just having extra people in the house has little effect with the lower reset temps. But, that bias is enough to overcome cold, clear, windy nights and allow the system to maintain house temp.

    It's not predictive, like what Nofissil is after, but it is an affective real time control strategy.

    I belive Tekmar has a system where the reset controller looks at the actual room temp and room setpoint, along with the outside temp, to determine the water temp. A step up from what I have, no doubt.
  16. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    I have the Tekmar, which my installer thought was the greatest thing since sliced bread. I don't know. Probably Joe Brown or one of the tech guys here could tell you better than I . . . but Viessmann says their system is actually meant for constant circulation, not room stats. I actually program my boiler for a desired day and evening set back temps. But all my zones have stats, so I think we got some basturdized euro-American stuff goin on. If only the Euro's would send that Swedish chick to check on my system . . .

    Makes sense to me to keep the water moving all the time to even out the surface and air temp by changing the water temp and the speed of circulation. But then, that just me makin up stuff . . . no idea about the engineering behind any of it.
  17. Eric Johnson

    Eric Johnson Mod Emeritus

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    In Europe, I think they do a lot more with constant circulation and four-way mixing valves on the zones. It's not a concept that has got much traction on this side of the pond, but I think it makes more sense than extreme hot and cold cycles.

    Good thing you're not driving around in the Park today, Jimbo. Some pretty slick roads on the way to work this morning, and it's a tad nippy.
  18. henfruit

    henfruit Minister of Fire

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    nippy is when the wind doesnt blow. but yesreday was just freezen. this am was 5 and all the water buckets inthe barn where frozen. time to move some heat into the barn. yup things dont seem to stop running when it is this cold. 6- 12 more tom, where do i put it? just ordered chains for the tractor so i hope i dont get stuck any more.
  19. wdc1160

    wdc1160 New Member

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    I have an HVAC company that I work with Eric and they also are huge fans of putting mixing valves on every zone for every possible temp. Between those guys they have every HVAC degree you can have so I don't argue with them.
  20. heaterman

    heaterman Minister of Fire

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    Windchill of animate vs inanimate objects.

    Windchill affects a persons ability to stay warm to a much greater extent than it does something like a house in the purest sense of the term. The process involved is an above normal rate of heat lost (for a given temperature) due to an increase in evaporative cooling. More air moving past your skin increases the rate of evaporation from your bod. More evaporation = more heat lost.

    Houses don't perspire like we humans do so logic would dictate that windchill does not have the same evaporative cooling effect on a structure.

    BUT!!!!!!

    Wind velocity plays a huge part in something that does affect houses and that is the air infiltration rate. Think about the pressure difference on the windward side and the leeward side of your house, as caused by a 20 mph breeze for example. The windward side is seeing a greatly increased pressure and the leeward side is in a negative condition. Now you have things set up to move air through every crack and crevice in your building in a most expedient manner. Any and all openings no matter how small become paths for huge amounts of heat to be moved from your living room to the great outdoors.

    So.............long story short.......claiming that your house suffers "windchill" is not correct but claiming that it "seems to heat harder" would probably be spot on. Pressure differential can create a huge loss of heat due to increased air infiltration.
  21. mtfallsmikey

    mtfallsmikey New Member

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    And, I have decided to locate my boiler on the leeward side of a storage building; easy to build the woodshed on to the building, and protect the boiler from wind/blowing snow. Windchill / prevailing winds are never factored into a heat loss equation, cuz there is no way to calculate the effect.
  22. sled_mack

    sled_mack New Member

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    I know that wind chill does not affect objects the same as bodies. But isn't there more to it than just the evaporative effect?

    Imagine a solid block of steel heated to 150 deg and set out on a 0 deg night with no wind. It's going to take some time for that mass to cool down. Now, imagine the same block heated to 150 deg and set outside on a 0 deg night with 30 mph winds. It's going to cool faster. With no wind, convection is the only (well primary, there would be radiation too, I think) force removing heat from the block. The wind provides "forced convection", for lack of a better term.

    The difference is that wind chill continues to strip heat from us, because our bodies try to replace it. That steel block, no matter how windy it is, will only go down to 0 deg if it sets out there long enough. It can never get colder than the surrounding air because of wind chill.

    Have I been confused on this all of these years?
  23. slowzuki

    slowzuki Feeling the Heat

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    Loc:
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    Its the "h" factor in a convective heat loss calc and the first part of your description is accurate. Natural convection has a certain h value and forced is much higher.

    The convective heat loss formula:

    q"=h(Ts-Tinf)

    q" is rate of heat loss kW or BTU/hr etc
    h is the convective coefficient
    Ts is the surface temp
    Tinf is the temp far away from the surface such as the wind or ambient room temp

    So, double the h, double the heat loss.
    Double the difference in temps, double the heat loss at least, since h can be partly a function of Ts.


    Where it gets complicated is as Ts gets hauled down, the radiant losses drop, but conduction through the wall assembly increases, so you can see how things get interesting.
  24. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    The ultimate solution is an adaptive system with btu monitoring.

    It works like this... you have a computer that actually manages your heating system. Each zone has a btu monitor, which consists of a flow meter (just like a water meter for those with town water, but designed to withstand high temps) and a temp sensor on the supply and return for that zone. Outdoor reset is simple and inexpensive, but what we actually care about is the number of btus being used... the outdoor reset curves are just approximations.

    Now, we know how many btus are being used by each zone, and we have a room temperature sensor, and an input device that lets you tell the system what temp you want that room to be. So, the computer sitting in the basement says, "hmm... the temp in the room is falling by 2 degrees per hour, and will drop below the desired temp in 15 minutes," and starts circulating water using a variable-speed circulator. It knows from the last time that it heated this zone, that the zone absorbed heat at a rate of 15kbuth, maintaining the desired temp. So, it looks at the supply water sensor, and adjusts the circulator flow rate to deliver 15kbtuh.

    This time, however, at it watches the room sensor, it notices that the room is not heating as fast as it did last time. So it anticipates that the remaining heat in the boiler will not be enough, and fires up the burner, while increasing the flow rate to use the current water temp more effectively, until the burner has time to heat the boiler. Now it is modulating the flow rate to the supply water temperature such that it is dumping 20kbuth into the zone, and the temperature of the room is behaving as-desired in order to keep it within 1 degree of the desired temp. It decides that the room is warm enough and shuts down that zone, storing the 20kbtuh figure for the next time.

    With a system like that, it doesn't matter if the heat loss is due to cold outdoor temperatures, or high winds, or because someone is painting the room and left the window open without turning the "thermostat" down. The system will adapt to the conditions, as defined by the behavior of the heating zone, itself.

    To go one step further, we add that outdoor weather station, giving the computer weather data (temperature, wind speed and direction, precipitation, insolation) and now it can compare the monitored behavior of the zones to the outdoor conditions. After a few seasons, it will have a very good idea of what effect the weather has on each heating zone, and will be able to anticipate behavior based on the weather, not just the last cycle. But it will still monitor and adapt during each cycle, in case someone does leave a window open, or someone is sick and turns the room temperature up, or someone cuts down a tree that had been shading a portion of the house, or there is a snow drift against one wall. Or whatever.

    The same could be applied to cooling, as well, particularly with advanced chilled-water systems and variable-speed equipment.

    Why don't we do that? The answer is, of course, money. That's a very expensive system, just to get a handful of percent more efficiency. You get a lot more "bang for your buck" with other upgrades (like better windows and insulation, and wood-burning equipment, and radiant heating, and such).

    For larger applications (eg, schools, office buildings, warehouses, etc.) those few percent might be enough to justify the cost of a system like that, but the development cost would be high, and it would take many years for a company developing that technology (to the point that it is reliable, user-friendly, and profitable) to ever see a return on the investment, due to the low level of demand.

    Joe
  25. sled_mack

    sled_mack New Member

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    Joe, I was very close to building a system like that. Not quite that complex - I wasn't planning on zone flowmeters or variable speed pumps. But, room sensors, floor sensors, and a central interface to adjust room setpoints and view feedback from the system. It would be a neat project, provide excellent comfort, and maybe gain some efficiency.

    What ultimately caused me to drop the plans was how to "cut over" to standard thermostats if something went wrong. How would my wife deal wiit it if I'm away on business and some part of the system died? No HVAC guy is going to even want to take a look at it. Would I be able to sell my house with this setup in it unless the buyer was another controls engineer?

    My hope is that some of these features start working their way into standard boiler controls. It will be slow, one feature at a time, I'm sure. But today, processing power is not a limitation. Modular controllers, memory, and I/O would allow quick and easy recovery of a down system. And reliability of those parts is good these days, too.
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