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Burner Controls

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by ejhills, Oct 17, 2013.

  1. ejhills

    ejhills Member

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  2. ewdudley

    ewdudley Minister of Fire

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    Abatement company? Even here in regulation-happy New York a residential property owner can deal with asbestos as he sees fit in his own home. "This Old House" would have you believe that it's necessary to invite in all manner of charlatan and hand a blank check to each, and they're in Massachusetts so perhaps that's what they deserve, but that need not be the case.
    Last edited: Oct 22, 2013
  3. BoilerMan

    BoilerMan Minister of Fire

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    This is one of the best statements I've ever read on Hearth.com!

    TS
  4. Nofossil

    Nofossil Moderator Emeritus

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    Thanks. I get a little wound up about regulatory nonsense. It's good practice for me to force myself to write calmly.
  5. ejhills

    ejhills Member

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    Hello All,

    I think I have a simple solution to get the btu out of the storage on a TT call. And the wiring would be extremely simple.

    Return pumps in parallel under seperate controls, the wood aquastat and the burner aquastat.

    What side effects might there be?

    Ed

    Attached Files:

  6. heaterman

    heaterman Minister of Fire

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    I think it would be simpler and you would get better results if you plumbed your storage like a hydraulic separator. In other words..... Pipe the wood boiler into one side of the tank with supply high and return low, then do the same on the other side of the tank with the pump currently circulating you heating system. Simply take the "house" side of the storage tank and pipe it into the return line just ahead of the current boiler pump via 2 closely spaced tees with a ball valve between them.
    You would take the return water coming back to your pump out of the top tee, then bring hot supply from the top of your storage into the bottom tee.

    That way you don't have to bother with a second pump at all.
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  7. maple1

    maple1 Minister of Fire

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    Do you have return temp protection on your wood boiler? That would bypass it, which might not be good for your boiler at times.
  8. maple1

    maple1 Minister of Fire

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    Are you talking pressurized storage or open?
  9. ejhills

    ejhills Member

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    Open
  10. ejhills

    ejhills Member

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    There is a mixing valve, first thing on the supply side.
  11. __dan

    __dan Burning Hunk

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    I am starting to understand what you have done with the single pressurized storage coil immersed in an open storage tank.

    Given that, I do not see any easy way to get the operation you want just by cycling the circs. My feeling is my earlier suggestion would yield more forward progress. Abate the old oil boiler. You say you know it is coming out. With the old oil boiler out of the picture, you would most likely rethink your plumbing plan and maybe go with one of the standardized plumbing diagrams.

    Of of the problems of what you propose is that the wood boiler, storage, and old oil boiler are all on the same series loop. Essentially, you're using all three for storage. But the problem is the two boilers are less insulated and have flue draft losses so they cool more quickly. At a later time when you want to call storage, the boilers in series are cooler and work as loads and not sources.

    You can certainly battle this by burning more wood, but you can not realistically ask the board to help you do something that is inadvisable. Your premise would be you are asking for changes that will yield the desired result. You ask for help, not how to burn more wood for less heat.

    You do not need two circs in parallel. There is a way to call one circ with parallel switch contacts. Using both boilers and the tank as storage as your drawing shows, you would call the boiler circ with the wood aquastat and an isolating relay switch contact slaved on the house load circ. The boiler circ spins when the boiler is firing and / or when the house load is calling. Essentially, you would be scavenging residual heat from both boilers and storage for demand, when the wood boiler is off. This is what you have plumbed, no real way to separate storage from both boilers without rethinking your plumbing.
  12. __dan

    __dan Burning Hunk

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    Editing to add:

    It is possible the return protection mixing valve would close as the boiler and storage cool, isolating load from the boilers and storage.

    In that case the above suggestion will not work.

    You may have to add a circ between the storage tank and the old oil boiler. Then the wood boiler return circ is only connected to the wood aquastat. The new supply header circ is called from the house load circ using an isolating relay and the wood aquastat in parallel using an isolating relay.

    Do not call the new header circ from the old oil boiler. Only call when there is demand in the house or when the wood boiler is firing.
  13. __dan

    __dan Burning Hunk

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    No, even adding the header circ will not be enough. When the return protection mixing valve closes, the loop between the storage coil and the oil boiler will be blocked at the valve and no flow for scavenging of the residual heat.

    You need to determine what you want to happen. Do you want the old oil boiler to stay or go. Then you need a plumbing plan that implements your desired result. Once it is plumbed, you can wire it.
  14. ejhills

    ejhills Member

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    I understand this and accept the reality of the heat loss and the need to keep the wood boiler warm. Its what I can afford now. What would be great is a drawing of how this "parallel switch contacts and an isolating relay switch contact slaved" is wired.
  15. __dan

    __dan Burning Hunk

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    The return protection mixing valve, if it is working properly, will start to close below 150 deg F and block all flow in the series loop you are showing that you have now. For this reason what you propose is impractical. Calling the circ will not matter, as with no fire in the boiler to keep it above 150, 160 F, the flow path will be stopped at the return protection valve (if the valve works properly).

    The wiring diagram you ask for, if you ask an unlicensed person for that, liability will attach to you the homeowner. That information is readily available to you by consulting a teacher at a local trade school. If you ask a licensed person for that, liability for claims will spread out to those nearby the negligent loss.

    Do you carry fire insurance on the property and plan to make a claim on it if you have fire loss or freezing pipe and water damage. If so, your insurer is party to your boiler install and you need to disclose to them. Show your insurer what you are doing and ask them for their guidance, ask for their wiring diagram. Have them tell you what to do since they are liable for your actions.

    I believe you can afford to do the job right, I have no doubt about that. You cannot afford to do the job wrong, neither can your insurer or dependents. Clearly, you need some experienced trade professional help, but you are not at the point where you have made that finding for yourself.
  16. __dan

    __dan Burning Hunk

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  17. ewdudley

    ewdudley Minister of Fire

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    Here P1 is BB function. Weighted checks prevent thermosiphon. (Missing dump zone, expansion, valves, etc.)

    [Edit:] After looking at it, may need a zone valve to prevent excess parallel flow through old boiler when BB not calling. No big deal, probably just plan for possibility and add later if needed. Flo-chek or weighted check in P1 circuit would help.

    201310231937sys.png
    Last edited: Oct 24, 2013
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  18. __dan

    __dan Burning Hunk

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    That's incredible ewdudley. I was thinking the only way out of his dilemma was 800 gallons of storage as the manual says.

    Looks very elegant and puts him two checks and a circ away from where he is now.

    With the boiler firing it looks like it prioritizes the load with some heat going to storage in parallel.

    With the boiler off it looks like it scavenges heat from the wood boiler until the return protection valve closes, then scavenges from storage. Elegant

    You are a creative genius.

    Because the boiler is much bigger than the storage and much bigger than the load, he may need the old oil boiler also as storage (to absorb boiler output). P1 would spin when the wood is firing and when there is call for heat from the load


    .
    Last edited: Oct 23, 2013
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  19. ewdudley

    ewdudley Minister of Fire

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    I wish. Left hand side was lifted from the Tarm reference designs. And NTS, since apparently you're not familiar with schematic representations.
    Last edited: Oct 24, 2013
  20. ejhills

    ejhills Member

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    Good Morning All,

    For my ignorance I beg your forgiveness and thank you for your input.
    The double check looks beautiful. However I must be missing something because I see water moving in 2 directions through the coil when P1(BB) and P0(Wood) are both on.

    Or does P0 get cut? And both Wood AQ and BB provide logic for P1?

    Thanks
    Last edited: Oct 24, 2013
  21. ewdudley

    ewdudley Minister of Fire

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    If P0 flow > P1 flow then the difference flows from top to bottom of storage coil.
    If P1 flow > P0 flow then the difference flows from bottom to top of storage coil.
    If P1 flow == P0 flow then the difference is zero, no flow through storage coil.
  22. ejhills

    ejhills Member

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    Because both checks will close.... :)
  23. ewdudley

    ewdudley Minister of Fire

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    All three pumps are independent. P2 only cares about call for heat, C1 C2 activated by TT; P1 only cares about high limit, B1 B2 activated by L8148A TT and aquastat; and P0 only cares about moving heat away from the wood boiler, activated by factory boiler controls. If storage runs out of heat then P1 and P2 will run forever, but presumably somebody will come along and turn the system off sooner or later in that case.

    Again, the two weighted checks are just to prevent thermosiphon, they may not be needed depending on how your physical piping is set up.

    I've never seen one, but there is such a thing as a L8148A with a minimum high limit of 180 degF, which might be too high for what you're doing. A normal L8148A will go down to something like 140 degF, which should be plenty low for a poor man's outdoor reset.

    Also all L8148As have a fixed hysterisis of 15 degF IIRC, which may be too little to work really well, but it should work well enough in the meantime to find out if it's something you'll be happy with.
    Last edited: Oct 25, 2013
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  24. ejhills

    ejhills Member

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    After I get this loop of checks installed, I think a "triple" on the old oil boiler to replace the L8148A would be in order. A low limit on BB to keep water moving.

    My goal is to have the thermostat set with 2 times/temps. Morning @ 67 and Nite @ 62. A fire in the morning and a fire at nite. Trying to get in front of the call for heat.
    Last edited: Oct 26, 2013
  25. ewdudley

    ewdudley Minister of Fire

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    Aren't 'triple' aquastats like the L8124A used to maintain minimum boiler temp to prevent flue gas condensation and primarily to maintain water jacket temperature for DHW tankless coils? It doesn't seem like you need to worry about either with your setup.


    Not sure what you mean. I thought call for heat was a thermostat closure across TT.

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