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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. maineDIY

    maineDIY New Member

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    First time post, long time reader. Appreciate the fine info given here. Question for the gurus: is baseboard hydronic heat really a reasonable match for a gasification boiler? I ask because it seemed to be a pretty elegant solution to keep the oil delivery truck away to just hook up one of these jewels to my existing distribution system which is oil fired hot water baseboard. The problem that I see now that I've gone thru the time and expense of installing the boiler (60 kw Vigas with 1000 gal propane tank storage 50' from house) is that the baseboard system requires 180deg water at minimum. This is very near the top of the design limitation of the boiler /storage system ---which to me isn't a very good design. A lot of the heat generated by a burn and stored in the tank is not useable. One then is constantly just topping off the storage tank temperature wise, rather than having infrequent big burns. Furthermore, no matter how well one insulates, the losses are bound to be greater with higher storage to ambient gradients. I understand that radiant operates at lower temps. Does that need to be the next big project---to install radiant? I'm hearing ca-Ching.

    One last question. I read on the "fine tuning the Eko" long sticky thread, something to the effect of turning down the fan, to produce a slower, cooler burn so that the heat doesn't just go up the flu. Is that statement evidenced based and is that opinion generally shared here or just someone's theory?

    Thanks in advance.

    Gregory

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  2. bigburner

    bigburner Feeling the Heat

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    is the house warm a lower water temp, say 140F. My guess it will be, until the coldest days and those days you will be chucking wood in the thing anyway. If it doesn't you are way under sized for base board. In the old days we ran it on every inch of outside wall possible, then ran like 160 F water. Now well it's all in floor ,underfloor and HW/AC air handlers.
  3. maineDIY

    maineDIY New Member

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    Well you make a good point/observation---there really needs to be more baseboard, but at 140 the house won't stay warm.
  4. hiker88

    hiker88 Burning Hunk

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    Hi,

    I'm in the same situation as you. I'm baseboard only and considering converting to a gassifier.

    It's really about the math. I don't know the formulas yet, but I'm working on understanding it. If you know your heat load (math mumbo jumbo), how many feet of baseboard you have (more math) and then know the btu output your baseboard is rated at per inlet water temperature you will know how you stand.

    That being said, I have done a lot of anecdotal testing over this winter with my oil burner and my baseboard. I have found that my house easily maintains 60 degrees with the aquastat set at 130 low set point, 150 high set point with a 10 degree anticipator set point. I've done this on our coldest days and nights this year to simulate a low heat situation (either night or when we are away at work to simulate the system running off storage). Of course I can easily get the heat of the house well up over 70 degrees if I change the aquastat to 180 low 200 high to simulate a boiler running flat out with high heat load.

    I would still like to add some panel radiators selectively throughout the house. I grew up with them in Germany as a kid and they were great to hang your towels over while you were in the shower. Nothing like heated towels to dry off with :) Oh yea, they'll stretch your storage capabilities out too.
  5. maineDIY

    maineDIY New Member

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    Well I'm OK with math, but my point is that the baseboard really requires 180 deg inlet temp to put out its rated output. To me, not a good match for a system that can barely make that temp. I really didn't consider that fact when I sprung for the gasser.
    GG
  6. Dune

    Dune Minister of Fire

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    You need to install more baseboard. Also, how is your insulation, windows, doors, weatherstripping etc.?
    Other than than that, yes radiant floor heat would give you much more storage.
  7. flyingcow

    flyingcow Minister of Fire

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    More baseboard. i have basically the same set up. But i have my kitchen done with staple up Radiant. A nice add on. eventually will do all first floors with staple up. I need close to 140 in the dead of winter to maintain the staple up.
  8. Duetech

    Duetech Minister of Fire

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    At least some of the baseboard mfg supply general info for needed linear ft of baseboard/sq ft of heat space and port sizing reference charts. Those I recall looking into used 170* as a recomended referrence. One store that uses the "save big money at" has similar baseboard you can link to on the net and see their sizing chart. One definite consideration is the size of piping and inlet at the baseboard and the size of tube that it uses. Higher heat is needed for smaller diameter piping. Also finned or not could be an issue. I am looking at baseboard myself and it seems that here 160* seems to be the better part of the low end for baseboard with no recomendations for anything below 150*. My "hunt results" are not conclusive but are just gleanings for my curious mind (dubious interpretations excepted for those who like to snicker....snicker, ...snicker). Since you have sprung for the gasser it might do to find what kinds of temperature drop you are experiencing from your baseboard inlet and outlet. Your new boiler should be able to withstand a 140* return and still supply a 170-180* source. If you have a substantial drop in temps It might suggest too low of flow to be effective at lower than 180* temps. With my current air/water hx I need 140* and above to effectively heat the home. Things don't really get good until it gets into the 150* + range. Baseboard is my "potential" summer time project.
  9. in hot water

    in hot water New Member

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    To get more output you need more temperature or a baseboard with higher output (more and/ or larger fins).

    Increasing the flow rate will make a small change in output as the average temperature across the board increases, but too fast of flow causes noise and possible erosion corrosion. Usually BB output is rated at 1 and 4 gpm flow.

    But a few things to check with your current baseboard.

    The baseboard needs to be able to have a good air flow, top to bottom. Make sure carpet has not blocked some or all of bottom opening. Curtains above or over the BB will change the output, as will furniture pushed tight to the baseboard. Dampers need to be wide open if you have the adjustable type. Custom made enclosures often hamper the airflow.

    I have seen BB installed with the fins facing front to back:) Make sure the fins are open top to bottom.

    Sometimes a good brushing and vacuum job will increase performance. Even a small layer of dust or pet hair reduces output.

    Certainly anything you can do to lower the heatloss will help, close the drapes, seal any air leaks around the doors and windows, etc.

    hr
  10. ewdudley

    ewdudley Minister of Fire

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    Of course to maximize storage capacity you need to minimize return temperature. I've found one way of doing this that has worked out pretty well.

    We put in a 30 gallon buffer tank/hydraulic separator that the zones pull from, and then there's a transfer pump that pumps from storage to the buffer tank according to the temperature near the bottom of the buffer tank. A key component is a Wilo Stratus (or Grundfos Alpha, if you prefer) constant pressure pump for the loads, which is set fairly low to flow slowly almost constantly.

    The temperature sensor in buffer tank is up about a foot from the bottom, and it's controlled by a simple Ranco aquastat. The aquastat is set by trial and error to find some setting high enough to keep the house good and warm. You can also adjust the return temperature setting seasonally. This is just a poor-man's outdoor reset, you could get a Tekmar control that would optimize everything very nicely. Even with a lot of baseboard we can usually do nicely with the return-to-storage temperature set to 120 degF and a supply temperature of 175 degF, although if it gets extraordinarily cold and windy I run supply temperature up over 180 degF.

    This way all the water pulled from storage only ever makes one trip per storage cycle, and doesn't return to storage until it has been depleted for all its worth in our particular system. Another benefit is that zones that cycle intermittently and/or have high temperature deltas will separate colder water to the bottom of the buffer tank, and undersized zones that run nearly constantly with low temperature deltas will see their return water separate up higher into the tank. The end result is lower composite return temperature to storage and 175 degF water more of the time to the zones that need it.

    We now have a couple low temperature radiant zones, which pull water from the bottom of the buffer tank and then through a mixer. The check valving is such that the radiant zones return directly to storage, which means they force their net unmixed flow to supply to top of the buffer tank, where the high temperature zones get first dibs.
  11. lukem

    lukem Minister of Fire

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    Good post. I'm considering a wood fired boiler of some sort in the next couple years and have often wondered the same thing. My vintage 60's propane furnace is rated at 200k btu, yes 200, and feeds some old cast iron radiators in the basement and baseboard on the main level.

    Since the furnance was installed the house has received insulation upgrades, new windows and doors, and is genarally tighter overall. I haven't run the furnace in a couple years, but if memory serves correctly it would run in a short cycle with a lot of time in between firing. The system tempt measured at the furnace rarely got to 180 and almost never to 200. I think I've probably got more baseboard than I need now that the heating demand is less, so I think I can get by with lower temps. I think.

    Sound reasonable?
  12. flyingcow

    flyingcow Minister of Fire

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    More baseboard means lower temps to heat house. Plus those cast iron radiators are a plus.

    Thats basically how radiant floors work. You've got a lot of square footage of heat in a radiant floor. Plus the radiant floor keeps the wife's feet warmer. This is a big plus!
  13. ALASKAPF185

    ALASKAPF185 Member

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    Quick answer is yes, baseboard can work just fine with WB's. When using outdoor reset and programed heat curve, your baseboard will rarely see 180* water, only on the coldest days. Now there are 2 types of base board, actually 3. Cast iron ( requires the hotest temps) most common single pipe slant fin, and finally the 2 pipe design specifically for lower temp applications - condensing boiler and temps below 140 and still outputting more btu's than the single pipe slant fin at 180. Even when our boilers are set for 180 temp the base board rarely sees anything above 170. 160 is the code temp limit on the radiation fixture itself. This is where having a true design professional can make use of your equipment properly. With mixing valves, ODR controls and proper size pumps you can make the simplest of systems very comfortable and efficient.
  14. maple1

    maple1 Minister of Fire

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    I've got standard slant fin on my oil/wood combo smoker. It works fine - you certainly get more heat out of them when the temps are higher (180-200) but they seem to maintain OK down to 160, or even to 150. I am sure it would do just as well with a gasser & storage. But having said that, I am thinking maybe I should start to check out radiation that would work better with lower temps. It was unheard of when I did my house 15 years ago. Not sure it would be worth replacing all my slant fin though - was thinking more along the lines of just adding it to what's there. Are the new 'lower temp' panel rads still capable of using the hotter 180-200 temps? Or would they require mixing to lower temps as in-floor does?
  15. woodsmaster

    woodsmaster Minister of Fire

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    You might want to consider upgrading to rad panels or some staple up radiant. The panels are usually fairly easy to install
    depending on the house. I have rad panels and really like them. You can zone each room by its self and having a warm towel
    after a shower is really nice.
  16. maineDIY

    maineDIY New Member

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    Thanks for all the great comments and advice. I have the slant fin BB and they put out some heat down to 140 but you can pretty much count on your tank to be exhausted by then for heating purposes. You'd better be close by to stoke the stove at that point or the house begins to chill. I'm attracted to radiant in that it is said to only need 130-140 to begin with. I'm theorizing that with the use of mixing valves I could utilize the heat much better as the storage tanks go from 190 down to 140 or even as low as 130 or less. ie. much longer time between burns with overall less wood use? Is my theory right? Also nobody commented on whether very hot, rapid burns are just sending heat up the chimney. Should the fan on a gasser be turned down from 100% if possible provided the air/fuel mixture is kept optimal?
  17. timberr

    timberr Member

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    Hi Maine,

    I had the same problem, the little secret the person who sold me the boiler never discussed. The fall of 2011 I upgraded my baseboard to SlantFin 15 basebaord, I did it foot for foot and what a difference! http://www.slantfin.com/index.php/products/baseboard-residential/fine--line-15. I have a Tekmar 260 boiler reset control, I have it set for a Max low of 140 and my storage last's all day even when temps are below zero.

    As for Fan setting I run my Eko at 50%.

    Good luck
  18. chuck172

    chuck172 Minister of Fire

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    Do you have the tekmar controlling a mixing valve Timberr?
  19. timberr

    timberr Member

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    No the Tekmar controls the Circ pump on storage, when the target temp is reached the circ is turned off and the circ on the primary loop continues to circulate, when the water running through the loop goes below the Diff setting the circ pumps starts up until the target is reach. This continues until the demand for heat is reached.
  20. chuck172

    chuck172 Minister of Fire

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    I'm confused timberr, but interested. Your boiler is heating your storage. You must have a circulator off the storage to your heating zones. How do you lower and maintain the storage temperature (180*) to 140* to the heating units?
  21. timberr

    timberr Member

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    You are correct, boiler heats storage. There is a circ on the boiler to move water to & from storage. There is a circ on storage to move water to Primary loop. There is a circ on the peimary loop to run water to the zones. So if the outside temp is 30* and there is a call for heat, the target temp (minimum temps set on Tekmar) watre is pumped to the primary loop, there is a temp sensor on the primary loop, when it reaches 140* the Tekmar turns the circ off and the primary circ circulates water through the zones when the water cools to 138 (2* diff) the circ pump turns one until it hits 142 then it turns off. Like I said this continues until the demand for heat is satisfied. Typically the Circ pump at 30* will run for less then 1 min. then turn off for 2-3 mins. When the temps get colder the Target temp increases.
  22. maineDIY

    maineDIY New Member

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    No, I've got a "fluid power energy" 3 way thermostatic valve.
  23. maineDIY

    maineDIY New Member

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    Not sure how the "15" was an upgrade. From what model or brand did you upgrade from? From the slant fin web page it would appear that the 15 might be a downgrade for me. I'm quite sure that I have the 30 now. I'm wondering whether one of the commercial Slant fins might work better. Thanks for your post. Curious how you arrived at 50% for the fan?
    GG
  24. timberr

    timberr Member

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    I went a checked (I have a unit still in a box) iw was 30 that I used. As for the Fan, first season wood was a little wet (MC 20 - 25%) I had to use 60-70% fan but I was getting "The Smell". Since I am burning wood in the 10% MC and running 50%, burns great, no smell. My theory was with the higher fin speed creating more pressure causing smoke to escape. I may be blowing smoke....
  25. chuck172

    chuck172 Minister of Fire

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    Timberr, Is that what's called an injection pump system?

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