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Heating a pool with Biomass 40 / 500 gallon storage

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by aforbes100, Jul 1, 2013.

  1. aforbes100

    aforbes100 New Member

    Joined:
    Nov 26, 2011
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    Loc:
    MAINE
    Hello,

    I have a Biomass 40 / 500 gallon storage.

    I am installing an inground pool (18x36). I live in southern Maine and intend to heat the water in May and late September / early October to extend the time I can use the pool. My plan is to connect a separate Phase III water heater from the storage tank and then circulate out to the pool pump. Please note that heat and hot water to the rest of the house will not be used during the time I am heating the pool.

    Questions
    1. what size underground insulated piping should I buy. It will be 100 ft of pipe.

    2. if I am only heating the pool (not the rest of the house), will this setup actually heat the pool effectively.

    Thanks for your help.
    Andrew

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  2. flyingcow

    flyingcow Minister of Fire

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    Jun 4, 2008
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    northern-half of maine
    I'll bump this to bring it back to the top.

    I've got an inground 18x36 also, but up in Aroostook County. I heat it with a 250,000 btu propane fired heater. But i only use about 75 gals of propane a year. It will heat it up 2 degrees an hour, so we only fire it up when it's needed. But we've got good exposure to the sun and a good cover. Pool will maintain 75/80 degrees in good weather on it's own. You get any warmer than that you want to pay attention to the pool chemicals. Algae grows quickly when it's above 80.

    I looked at hooking up my boiler to heat the pool. For me, it's easier to fire up the propane and bring it up to temp, than running my boiler wide open for hours. it takes some BTU's to maintain 30,000 gals of water.

    I'd say you want at least inch and 1/4 i.d. pipe. But others here will give you better info.


    Go to www.builditsolar.com some very simple and low cost solar collectors for pools. I had some rough ones put together, and it works well.

    But do get a good pool cover for the nights and cool days.
  3. goosegunner

    goosegunner Minister of Fire

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    I have a 16X32 in ground that I heat with my Econoburn 200 and 1000 gallons of storage. The storage and boiler about 160' from the pool heat exchanger. I have true 1" id pex and aluma pex running the distance.

    I have a 350,000 btu shell and tub exchanger right by my pool pump. I get about a 50 degree delta T and can bring the pool up 1.5- 2 degrees per hour depending on the conditions.

    We have found 80 is fine if you are going to be actively swimming. 86-90 is the sweet spot for young and old to stand or leisurely sit in the pool.

    Honestly I couldn't be happier with how it performs. It is so nice to be able to bring up the pool temp after a cool rainy stretch or if you are having a party. It has made out pool much more enjoyable.

    On a side note you have to be realistic about the season. If it is much under 75 degrees outside most people don't think about swimming much. We have also found that after Labor day the kids are back in school and there is so much other stuff going on the pool gets minimal use.

    I have swam in October but only to say that I did. The nights get cold and kill your pool temp in a hurry.

    gg
  4. goosegunner

    goosegunner Minister of Fire

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    I also have 2000' of 1/2" black poly pipe that is in a box about 50' from my pool. It is 5- 400' lengths. It is feed by 2" pipe to a manifold and comes back through a 1-1/2" to a dedicated solar return. It helps but it is not even close to the wood boiler. I haven't even hooked it up this year.

    gg
  5. goosegunner

    goosegunner Minister of Fire

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    I do not know what a phase III water heater is but can it handle the chemistry of pool water?

    gg
  6. heaterman

    heaterman Minister of Fire

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    There's no benefit to installing a HX that is larger than your boilers capacity to supply it with hot water. Your 40 is probably in the neighborhood of 100K actual output so unless you want to be able to drag BTU's out of storage quickly (and have low water temp protection for your boiler) something around that size is all you can effectively use.
    flyingcow likes this.
  7. goosegunner

    goosegunner Minister of Fire

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    From using mine I think the shell and tube pool heat exchangers are highly over-rated on their btu output.


    gg
  8. jebatty

    jebatty Minister of Fire

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    gg, don't know about your situation, but what I have seen on hx ratings is not that they are over-rated, but that the rating is based on an impractical if not nearly impossible operating scenario. Take a look at the specs for your hx and see what they are based on.

    Keep in mind that btuh is based on ::DTT and flow rate, and with an hx this needs to be considered on both Sides A and B, as well as approach temperature. The "impractical" side of the rating usually is tied to flow rate and ::DTT, showing flows of 25 gpm and up and a very high ::DTT. Think about what size of pipe you will need to carry the high flow rate over the distance needed (think pump head), and what kind/size of pump you will need to accomplish this, and the impracticality may become more obvious.

    Example: hx temperature rise from 60F pool water in to 125F pool water out = 65F; advertised flow rate = 30 gpm; then btuh rating = 65 x 30 x 500 = 975,000. Because of the "500" factor, any change in the ::DTT or gpm makes a big change in btuh. This example may be a bit extreme, but a 140,000 btuh (100,000 btuh average output) rated boiler at ::DTT = 20, and even a 200,000 btuh (140,000 btuh average output) rated boiler at ::DTT = 20, will never supply sufficient btu's for such an hx rating to be realized, and not yet even considered is pump head and pump sizing.

    It can be difficult to even find the specs for some hx's, and particularly specs that show the rating at different flow rates and different ::DTT's from that on which the specs are based.
  9. goosegunner

    goosegunner Minister of Fire

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    That is why I bought a heat exchanger that was rated much higher than I needed, similar to my forced air exchanger in my house. With fluctuating supply temps I wanted it to be forgiving for out put if the supply temp dropped below what it was rated at.

    gg

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