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Adding aquastat to EKO

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by hartkem, Sep 23, 2012.

  1. hartkem

    hartkem Member

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    Some of you probably read my post about overheat protection. I decided to use copper fin tube above my boiler. I will use a normal open zone valve to protect for power outage. Know I am thinking about using an aquastat to protect against overheating from a bad circulator while Im changing the plumbing around. My EKO is in an outbuilding separate from storage. I would think having it in the water jacket would be best. I noticed a black plastic cap on the top of the boiler and there is a plug under it. Is this wear you would attach an aquastat? I know very little about aquastats. I would need one to open the circuit at 210 and close the circuit at 195 or so to control the zone valve. Could someone point me in the direction of which one would do such a thing?

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  2. maple1

    maple1 Minister of Fire

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    Someone please confirm this or correct it (I'm still learning this stuff), but I think a Honeywell L4006 will do just that. It is a SPST stat. Will turn on a pump when it gets to set point, and turn it off when it falls back below.

    If you get a L6006, it is SPDT - so if you used one of those, you could have it turn something on at setpoint (the circulator), and turn something off at the same time( maybe the fan?). But not sure if that's a concern.

    They're similar common stats, and you can get them either to put in a well, or use a strap on probe (if you don't have a tapping to put a well in).
  3. A Honeywell l4006b aquastat is what I used. You need an one that closes or makes on temp rise. You can get one that has set 5 degree or adjustable differential. The adjustable allows you to keep the circulator on a little longer.
  4. Eric Johnson

    Eric Johnson Mod Emeritus

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    There's no place on the EKOs to sink a well, which is what you put the aquastat lead into. With an EKO, unless you create an opening for a well in the piping, you need a strap-on stat. However, you can easily create a 1/2-inch opening to sink a well into in your piping and probably get it close enough to work well, especially close to the boiler on the supply side. Like this:

    [​IMG]
  5. goosegunner

    goosegunner Minister of Fire

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    The Johnson controls A419 can be used and has many adjustments. They make a well that can be put in the pipe near boiler.

    The cooling mode would be used cut in at set point and off at differential.

    http://cgproducts.johnsoncontrols.com/MET_PDF/125188.PDF

    Mine will also be used to move more water when storage is nearing full charge. A second pump in parallel will start to move more water.

    gg
  6. hartkem

    hartkem Member

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    Wouldn't I want one that opens on temp rise. Normally open zone valve would need power to it all the time to prevent flow through the overheat loop. When a loss of power occurs or when temperature gets to high the aquastat would open the circuit allowing flow. Am I thinking correctly?
  7. Eric Johnson

    Eric Johnson Mod Emeritus

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    I think you're trying to do too much with one stat. In my system, the stat closes on temp rise, making the circuit and kicking on a circulator that moves the hot water into a dump zone, in this case, a greenhouse. That won't do any good in the event of a power failure. In that case, you'd need either a battery backup or generator or an Automag zone valve that opens up when the power is cut, allowing gravity flow into a dump zone of some sort. I think it's two separate functions, not controllable with one stat or valve.

    So, I have both on my system: one for quickly dealing with an overheat situation with the power on; the other to protect the boiler from an anticipated overheat situation when I lose power.
    mikefrommaine likes this.
  8. goosegunner

    goosegunner Minister of Fire

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    My fin tube is used only for a no power dump. It is wired separately from paralellel pump. If I wanted to use it as a overheat I could open the normally open valve with a RIB relay when parallel pump is energized. I want to be able to use the pump to increase gpm to storage not dissipate heat when I have power.

    The tank will absorb a lot of btus as a overheat if you can increase gpm. The fin tube is for no power safety. If all works as it should the tank will still be taking btus even in a no power situation, heat will also dissipate through the over head fin tube.

    gg
  9. maple1

    maple1 Minister of Fire

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    I think a 6006 would do that. When it gets to setpoint, it closes one circuit & opens another. So you could have the circuit that opens on rise run to a 24v. transformer then to the zone valve. And maybe have the circuit that closes go to a second circulator?
  10. hartkem

    hartkem Member

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    Looks like there a several ways of thinking here. I will for sure use the fin tube as a gravity flow overheat loop with a normally open zone valve to protect against a power loss. I was also thinking I could also just add the aquastat to also open the zone valve if the boiler got to hot. Under normal conditions the boiler won't get to hot unless the circulator pump failed. I don't have a backup pump in parallel. Do most people use a backup pump? Im not interested in adding one due to the amount of plumbing changes. Maybe the power loss overheat protection is adequate.
  11. maple1

    maple1 Minister of Fire

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    I think I would get a 6006, and wire the zone valve through it with a 24v transformer in between. It has two contacts, but you don't have to use them both. You could use just the break on rise side for now with the zone valve, and if you decide to do something with a pump later (e.g. maybe you find the dump zone doesn't flow good enough by gravity, or you just want to add a second pump for backup or redundancy), the control for it will already be there. I don't think there's much of a price difference between a 4006 & 6006.

    EDIT: I'm just using those aquastats because I'm somewhat familiar with them, there are likely other brands & models that will do the same thing).
  12. hartkem

    hartkem Member

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    Thanks maple1. I have the EKO 40 super and I still think I can put the aquastat directly in the water jacket. Under the black plastic cap on top of the eko is a plug. From the manual this appears to be where the emergency overheat protection probe for cold water supply is attached. You know the two pipes that no one uses. I have potable water in my boiler shack. Hmm.
  13. taxidermist

    taxidermist Minister of Fire

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    Yes you have a open hole to the water jacket for the over heat valve. http://www.newhorizonstore.com/Products/136-thermal-safety-valve-sts-20.aspx

    I ordered a well to put my temp probe for my controller in to see if I get better temp readings.
  14. rkusek

    rkusek Minister of Fire

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    What size is that well? It's not some metric or british pipe thread is it? Did you order one from New Horizon or somewhere else? I think Harkem could use a Honeywell or the JC A419. I have a A419 on my boiler water supply to my house and it works great. It would give you a second digital readout of your boiler temperature if you use it for overheat protection. The A419 would be connected to break the 24V supply to his NO zone valve. So a loss of power causes zone valve to open but the overheat on the A419 would also cause it to open sending water through the overhead finned tube. I know the A419 is DPST as well because mine closes 24V contacts to my air handler blower relay and also powers the 120 V circulator feeding my air handler HX. Like someone mentioned above it is the cooling mode setting of the A419. The 2nd set of contacts could be used for a secondary circulator to storage like others mentioned above.
  15. maple1

    maple1 Minister of Fire

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    Does the A419 have a built-in transformer?
  16. taxidermist

    taxidermist Minister of Fire

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    I ordered 1/2 npt i found one on ebay
  17. hartkem

    hartkem Member

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    Im not sure what size it is or exactly how to get to it. Its about and inch below the sheet metal. How hard is it to remove the sheet metal on top of the EKO.? Taxidermist can you let us know what you find when you remove the plug?
  18. maple1

    maple1 Minister of Fire

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    Is your boiler itself full of water and up & running (more or less)?

    If it was and it was me, I think I'd just get a strap on aquastat and tuck the sensor in close to the boiler body somewhere rather than draining & opening it up for a well.
  19. rkusek

    rkusek Minister of Fire

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    no but you can get a 24v or 120v one. Depends on what kind of dump valve you are using.
  20. taxidermist

    taxidermist Minister of Fire

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    The sheet metal is just held on with spring clips. Just grab the side and lift up. The plug on mine was just a pipe plug and it goes right into the water jacket.

    Rob
  21. hartkem

    hartkem Member

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    My system is up and running but its not a big deal to drain the outside portion since I can valve it off. I need to drain it anyway to hook up my fin tube overheat loop. I wonder if one would have to use a remote bulb type aquastat since that plug sits so far below the sheet metal. I am very unfamilar with aquastats so I don't know if a regualar vertical mount one would work. I guess it depends on how long the well is and whether is would stick above the sheet metal to attach the aquastat.
  22. maple1

    maple1 Minister of Fire

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    If it helps, I measured the clearance on my 6006. From the top of the boiler port (where the well threads in) to the bottom of the aquastat (closest part of that is the end of a couple of mounting screws sticking out from inside the aquastat) is 3/4". You might gain another 1/4" tops by grinding/filing down the ends of the screws. If that's too close you should be able to get enough by using a close or short nipple & coupling to raise the port up - although I'm not sure there would be enough room inside of that to screw a well into (it might not fit inside the nipple).
  23. rkusek

    rkusek Minister of Fire

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    I've got some 3/4" brass thermowells and will check it out today to see if they will work. The Johnson Controls A419 has a probe on a wire so I believe it would be as simple placing it in the well with some thermal grease.
  24. The reason I went with a l4006b was I could set it to turn on my largest zone at 194 degrees. It helps to keep the boiler from idling. And I get use of the extra heat instead of it warming up the boiler room or shed.
  25. Fred61

    Fred61 Minister of Fire

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    If I remember correctly, I purchased a 1/2 inch NPT .thermowell from a local plumbing supply (F.W. Webb). The distance between the skin and the top of the well is just about 1/2 inch too far to comfortably insert a standard aquastat. I would go with the Johnson Controls A-419 which has a long lead on the probe. I am presently using one to switch over to oil when my storage reaches my minimum setpoint. Meanwhile the readout serves as a thermometer that displays the tank temperature telling me when to fire up the boiler.

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