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multi set point aquastat?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by speedyvt, Sep 16, 2013.

  1. speedyvt

    speedyvt Member

    Joined:
    Sep 1, 2011
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    Loc:
    Southern Vermont
    Hi Guy's. I have a EKO-25 with 500 gallons of storage. The issue I am having is controlling the temperature of the supply. At a cold start I need to lower the setting on the aquastat to get the circulator to pump the water. Then the temp of the water drops so much so fast at the beginning I need to dial it back again. And I need to keep doing this until I'm up around 190 stove temp and the water temp is about 165 to 170. I then set the aquastat higher so when the boiler runs out of wood it doesn't keep circulating the water from the storage tank back through the boiler and actually cause my storage tank to lose heat.
    Its hard for me to explain I'm not a heating guy by any means. So I hope to get a digital aquastat if there is such a thing. To have multiple set points to do this for me. And I hope once you guys start responding that I can answer your questions and make thins clearer. Sorry for the crappy explanation to start.

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  2. BoilerMan

    BoilerMan Minister of Fire

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    Do you have return protection?

    TS
  3. 2.beans

    2.beans Minister of Fire

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    new hampshire
    ranco makes one that has two realys for two different settings
  4. maple1

    maple1 Minister of Fire

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    Sounds more complicated than it should be.

    As TS asks, do you have return protection? i.e., a thermostatic mixing valve to keep your return water above 140°?

    And I'm not familiar with the Eko, but there should be a way to get it to shut down when the fire is out rather than fiddling with more aquastat settings? There should be threads on here about how to make an Eko do that.

    Mine has an LK810 thermostatic loading unit, and it's tied to a flue gas temp stat. When the flue gas gets above setpoint, it turns the pump in the 810 on, and when it drops below it it turns it off. The thermostat in it keeps the return above 140 which keeps the supply from dropping like a stone. Works great, but it is pricey - like $6-700. You wouldn't need an LK810 - if you already have a circ that just moves water from the boiler to storage, you'd need something like a Danfoss mixing valve at I think less than $200, and a flue gas stat. One way or the other is fairly standard storage stuff - I'd be kind of surprised if you don't have return protection, that's pretty well a requirement with storage.

    My flue gas stat came with the boiler & loading unit, but you should be able to buy them separately. Might have to email a dealer to check that part out - Smokeless Heat is where my stuff came from. Not sure what they cost.

    What temp does your circ start at? Maybe it's just starting too low? I likely wouldn't launch much below 165°.
  5. speedyvt

    speedyvt Member

    Joined:
    Sep 1, 2011
    Messages:
    13
    Loc:
    Southern Vermont
    I do have return protection. The main problem is when I start the boiler the water may be 60 or 70 deg. But because the aquastat well is up on the supply pipe and set to 160 or 170, the boiler will get a over temp error because the water is not moving pass the well until the circulator turns on. The circulator pump worked off the boiler temp sensor originally, but because the boiler would continue to circulate after the storage was at temp and the fire was out we added the aquastat to fix the problem which it did but caused this one.
  6. maple1

    maple1 Minister of Fire

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    3,971
    Loc:
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    I think I would try to find a flue gas temp thermostat & use that for your boiler launch & shut down control. Contact Smokeless Heat (they are a site advertiser & have a banner ad on here), or one of the other site sponsors. It's a pretty easy install.

    My loading unit is run by that, but also is wired through a boiler-top aquastat (Honeywell L 6006) for redundancy in case something happens with the flue gas temp sensor or something. Primary control is flue gas temp, but if the aquastat sees hot water (I think I have it set for 190), it will take control & turn the pump on. Return from storage never sees temps that high, so when the boiler temp drops back below 190, control switches back to the flue gas temp and that stops the circ when the fire goes out.

    Or, you could return your circ control to where it was and likely should be (the boiler temp sensor), and get a timer wired in place that would shut it down after so many hours. Just reset the timer when you re-load or re-light. IMO not the ideal solution but I think others on here have used timers for boiler shutdown. There should be other EKO guys on here who have found ways to shut their boilers down at end of burn - that seems to be a design oversight to me.
  7. Fred61

    Fred61 Minister of Fire

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    In my system I charge the storage and distribute from it. What I did was install a Tecmar 156 to control the circulator that charges the storage. I placed the sensor on the boiler side adjacent to the sensor for the factory installed controller. Disconnected the circulator from the original controller and connected it to the Tecmar. The original controller now only acts as an on/off switch, low temperature shutdown on drop and a high limit switch for boiler shutdown on rise. Both sensors see the same temperature with this set-up. I set a high launch temperature for the circulator and a high low limit so the circs will shut down when the boiler starts cooling.

    You can also make use of the many other features of the Tecmar such as differential temperature, etc.

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