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Baseboard suitable for heat distribution?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by maineDIY, Feb 4, 2012.

  1. Rory

    Rory Member

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    I have standard baseboard in my house that was designed for my oil furnace, so I assume it expects 180 degree water. Since installing my Tarm 4 years ago, my water is rarely 180 degrees, but we're never cold and we hardly burn any oil. I suspect we are in "circulation mode" more than we were with the oil, but it maintains temperature quite well, and the electric bill doesn't seem to indicate that the circ pumps cost much to operate. It does take longer to raise the temp a few degrees, and it's hard to get much above 70 when it's extremely cold out. Thankfully, we're ok with it around 70 most of the time.

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  2. timberr

    timberr Member

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  3. b33p3r

    b33p3r Feeling the Heat

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    Used oil boiler hydronic baseboard for 11 years before installing econoburn. The only change I noticed is the house is warmer because we set the thermostat 2-3 degrees higher now that we aren't burning oil.
    The contractor that built my house has also told me that since a couple years ago they are recommending circulating 150 deg water through baseboard as opposed to 180. Supposed to save 10% or so on oil consumtion that way. I guess less cycles at boiler. They have installed a mixing setup on a few oil boilers to accomplish this.
  4. chuck172

    chuck172 Minister of Fire

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    I added more fintube to allow lower temperatures. I just couldn't figure out the easiest way to lower the temps to the emitters. When Timberr was talking about his system, it all made sense to me. Injection system. Like Timberr I only have 500 gallons of storage and I need to stretch it. Circulating 150* heat vs. 190* might do it. I'll give it a try.
  5. henfruit

    henfruit Minister of Fire

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    I have one room on the end of the house that is a bear to keep warm on the coldest days.The circ never seems to shut off.It is suspended radiant with 10 feet of base board tied into the the same loop.(was like that when i bought the house) My problem is not enough btu out put for the size of the room.It is not large but does have 7 + floor to ceiling windows and a cathedral ceiling about 15 feet..I was thinking to take the base board and make it a seperate zone (higher water temps) and add an other strip of base board 7 feet long. I have looked at some of the clip on plates to help disperse the heat better,hoping that that would help also.
  6. b33p3r

    b33p3r Feeling the Heat

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    I won't claim to be able to design what you need to heat a room. I will say what was designed for my oil boiler to heat is easily handled by my wood boiler. I have radiant tube run in my main floor joists using ultra fins but haven't insulated it yet or tied the pump in. Hopefully have it running by 2012-2013 winter. But I won't eliminate my baseboard until radiant is tested in the worst of temps!
  7. henfruit

    henfruit Minister of Fire

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    The boilers be it oil or wood not the problem.Not enough btus for that room as it is set up, and way to much glass. i would guess i need 10 to 15 thousand btus per hour at coldest design temp.
  8. maineDIY

    maineDIY New Member

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    "Of course to maximize storage capacity you need to minimize return temperature."

    You say that like that is a proven and well known fact. Is it? It would seem that a very cool return would just deplete your storage tank more quickly. There has to be heat transfer between the upper hot water and the relatively cooler lower levels, thus depleting the tank perhaps more quickly than with a warmer lower level tank temp. Your description of a "solution" sounds a little bit like a complicated Rube Goldberg defice. I don't really see how it makes the storage btu's more usable or the storage tank last longer. I've donned the asbestos suit---go for it.
    Gregory
  9. DaBackBurner

    DaBackBurner Member

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  10. maineDIY

    maineDIY New Member

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    [quote author="DaBackBurner" date="1328660278"]Here's one link that describes why it is important to maintain stratification within a storage resevoir for either heating or cooling applications.

    http://www.sciencedirect.com/science/article/pii/S030626190900141X[/quo

    I admit that it has been a long time since I studied thermodynamics so I don't think I'll spring the $41 for the full text as I likely wouldn't understand it anyways---but as best I can tell by the abstract, this article shows that causing stratification gives better storage as opposed to mixing, and explores some ways to maximize that, not that returning colder temp water will improve storage. Yes? No?
    GG
  11. DaBackBurner

    DaBackBurner Member

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    I believe...and it has been some time since I studied thermodynamics...seems like eons, but you want to be able to return the coldest water possible, while delivering the needed temperature water to satisfy your areas btu loss, because colder water will want to stay on the bottom as opposed to mixing with the hotter water up top and thus lowering that hotter water temperature quicker. This cannot always be accomplished depending on one's heat emitters though. I think it was Eliot describing a buffer tank solution that has me intrigued to utilize lower temp water for different type heat emitters, such as slab radiant or similar, AFTER say running through higher temp heat emitters like fin-tube or similar. If one can utilize that water BEFORE sending it to storage the storage resevoir will maintain better stratification hence it will allow the heat emitter distribution network to use storage for a longer period of time because the hotter water will stay hotter longer (up top) as it is not being mixed with say medium hot water (middle or so). Thus with the colder return water you develop better thermal layering.
    At least that's my WAY-less-than-expert understanding.
  12. ewdudley

    ewdudley Minister of Fire

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    Yes, the idea is to avoid sending any water back to storage until it is as cold as you can get it. With multiple zones with variable emitter effectiveness some zones will return cooler water than others, and the buffer/hydraulic separator tank can sort the coolest water to the bottom of the tank while the hotter returns can rise up and be cycled through again.

    The lower aquastat controls pumping water back to storage when it is cool enough, its setpoint is determined by trial and error. Too low and the house won't stay warm enough. Tekmar builds controls that can figure it out for you.

    The upper aquastat keeps the upper portion of the tank hot enough for DHW and the hot tub.

    The PEX zones pull from the bottom of the buffer tank and return directly to storage. This means when the PEX zones are calling there is a net flow from storage to the top of the buffer tank, where the high temperature loads can get a shot at it first.

    Attached Files:

  13. DaBackBurner

    DaBackBurner Member

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    Thank you for posting the picture Eliot. Now to start scrounging for a buffer tank. I'm equally excited because a friend is going to give me some lessons on welding, a skill I always aspired to have.
  14. maineDIY

    maineDIY New Member

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    Well I'm not sure I'm buying this cooler return theory. I do understand that heat rises and that thermal gradients will occur in the storage tank. However it would seem that the greater the temp gradient between the top hot thermal layer and the bottom cooler one, the faster the heat transfer between the two layers, seeming to me to offset the benefits of keeping the hottest water on top. Why not run one's return line above ground in the snow to get even a greater gradient? Not trying to be argumentive, just trying to understand.
    GG
  15. ewdudley

    ewdudley Minister of Fire

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    Water stratifies rather well and without some external disturbance it will remain stratified for as long as you please. Consider meromictic lakes that have remained stratified for thousands of years:

    http://www.waterontheweb.org/under/lakeecology/05_stratification.html

    That stratification is desirable is obvious considering the exponential decline in radiator effectiveness as a function of decreasing temperature difference according to Newton's law of cooling.
    Of course the underlying goal is to extract heat into the conditioned space, not reject it to the great outdoors. This is pretty much proven fact, not just some theory.

    Success in extracting heat from water into the conditioned space is measurable exactly according to the difference in the temperature of the water from when it enters the conditioned space to when it leaves the conditioned space.

    The greater the success in extracting heat, the cooler the water returning to storage. The cooler you can get storage before the next heating cycle, the greater the heat capacity of the storage, and therefore the greater the usefulness of the storage as storage.

    That's good. The more you understand the better you can argue, Monty Python's Argument Clinic notwithstanding.

    Cheers --ewd
  16. DaveBP

    DaveBP Minister of Fire

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    No it isn't.
  17. ALASKAPF185

    ALASKAPF185 Member

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    The dual pipe baseboard meant for low temp applications is called Heating Edge by smiths environmental products. Can be piped parallel, series or counter flow. At 110* degree water piped in parallel flow @ 2gpm it delivers 345 BTU/hr/ft. AN average 12x16' room can be heated with just 10' of this base board @ 110* water with a calculated heat loss of 15 btu/hr/sqft. Conventional baseboard would need 150* water thru a similar 10' section of slantfin. Low water temps and making use of old styles of radiation are becoming more popular. You might be able to find good schematics of applications on John Siegenthaler's website or articles. One such article that this info is from is in a free magazine " PM plumbing & mechanical" . Using lower temps also makes for a more comfortable and efficient system.
  18. ALASKAPF185

    ALASKAPF185 Member

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    Stratification is only a concern if the vessel being used is equal to the volume or within 150% of the system volume. Pretty much IDWH and solar buffer tanks. Lower temp returns are proportional , meaning it takes the same btu's to heat 1 cube 1 degree. There isn't any gain by returning it cooler in efficiency nor strat in a large buffer tank. Every system I touch gets an engineers approval before making any changes, anyone can put a system together, but to get the most out of it , all the details need to be calculated. We have several supply houses that do this for free. Anything you can find from John Seigenthaler is worth while reading, there is no better in hydronix. Good Luck
  19. DaBackBurner

    DaBackBurner Member

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    Are you saying then that I could supply from the bottom of (way over 150% system volume) a storage vessel and return to the top of it and maintain the same storage time between firings of my wood boiler because stratification is not important in a large storage/buffer tank? If that's the case then it will make it much easier to install my circulator pulling from the bottom of my un-pressurized storage vessel because the NPSH requirement of that pump can be achieved much easier. I did not know that stratification in a storage vessel of over 150% system volume was not a concern. :bug: It probably doesn't make any difference then of the mathematical modeling of that storage vessel, with regards to its aspect ratio, to have any bearing either.
    ...
    I would agree that anything from John Siegenthaler is worth reading...especially if one does.
  20. greynjaded

    greynjaded Member

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    Hi All,
    I might try some folks patience but wanted to share an experience with a basic failure to deliver the goods, (heat) after sufficient production.
    This was a 1950's multi family in NYC but try to ignore that.
    Heat source produced but at the radiators, or in this case baseboard etc. natural conduction is "delivery" method. The problem there was design.
    Everyone thought it brilliant and less of an eyesore to hide radiators. Consequence was even poorer air flow and added heat loss.
    Small low voltage fans with heat sensor/switch increased the efficiency with out too get a cost.
    Point, air flow could be increased across the surface area of your baseboard fins, panels etc for a rather low tech fix.
    Of course if it doesn't work, blame me and chalk up the $12 loss. Yes return temps will change.
    But to be honest, that was a 77 unit b'ldg and I hated the place. Curious what y'all think.
  21. woodsmaster

    woodsmaster Minister of Fire

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    There may not be a gain in efficiency but there is a gain in the time you can go between fires. Keep your hot water on the top and the cold on the bottom.
  22. ALASKAPF185

    ALASKAPF185 Member

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    No, where would you get that? Maybe I should have explained in laymans terms for you, I don't like to type that much tho. JS has a nice article out this month on it, carefully explaining the natural effects of strat and how in smaller tanks it can be beneficial to have a baffle to separate layers because of their smaller volume can quickly be overcome by system volume

    Appreciate your sarcasm.... it goes well I am sure you had your system professionally engineered, you don't sound like one of those that just did alot of internet research and slapped it together, or the typical old school installer that treats all systems the same. cheers
  23. velvetfoot

    velvetfoot Minister of Fire

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    Sorry for bringing up old thread, but it's very interesting to me.

    I just read a little about the Smith's Environmental Heating Edge baseboard; it seems like the cat's meow for replacing an existing baseboard. My baseboard is two zones, up and down, and single pass (in series), if that's the right term, for each level.
    Can Heating Edge be used to simply replace that baseboard I described?

    I saw an 8' section for $240 on line. So, it would be a hit to replace everything.

    Although I don't have a boiler (yet), the upstairs could use some more efficient baseboard to heat it up quicker with less cycling of the oil boiler (which is non condensing with an outdoor reset), since the insert heats the downstairs pretty well.

    Thanks.

    Edit: I just looked at their website, and it seems that running the two pipes in parallel gives the most btus/ft, so that should work out.
  24. Eric Johnson

    Eric Johnson Mod Emeritus

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    Instead of in floor radiant, if you want to replace or augment the baseboard, I'd highly recommend cast iron radiators, though not on the same zone as the baseboard. Personally, I'd consider replacing the baseboards entirely with cast iron.

    As to the idea of modulating the fan for a longer burn, especially on cold nights, that's been my experience. Worth playing with for a longer burn, IME.
  25. velvetfoot

    velvetfoot Minister of Fire

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    Not sure if I could get my wife to go along with cast iron radiators, even if I could find enough of them in the right sizes. I don't think she'd even go for panel rads, never mind the piping changes on the second floor. I like the idea of take the old one out and put the new, better performing, one in. Might even be possible for a room or two before the winter. Again, not cheap, but easi(er) - for me, lol.

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