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Taco HEC-2 Bumble Bee Reverse-Acting Control

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by ewdudley, Mar 18, 2013.

  1. ewdudley

    ewdudley Minister of Fire

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    Just got a response from Taco online customer support and they report the although the HEC-2 does not currently offer reverse-acting control, the capability should be available 'before the next heating season'.

    This interests me for return temperature control, but it seems like it could have other interesting applications.

    --ewd
    Coal Reaper likes this.

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  2. Coal Reaper

    Coal Reaper Minister of Fire

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    i ordered one for my loop to the house
  3. DaveBP

    DaveBP Minister of Fire

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    Been a while since I was researching it, but I remember wondering about the same issue with Tekmar's variable speed differential controls.Anyone know?
  4. ewdudley

    ewdudley Minister of Fire

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    The Taco Variable Speed - Setpoint (00-VS) and 00 Variable Speed Delta T (00-VDT) pumps, which incorporate a Tekmar controls, do already offer reverse-acting control, but with PSC motor pump and for some reason more expensive in some cases.
  5. Karl_northwind

    Karl_northwind Member

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    I've installed the 356 variable speed injection mixing control a number of times and I don't see any way it could be made to do it in reverse. nothing as simple as reversing sensors. Maybe if you installed it on a N/C triac? it would reverse operation, and then if you reversed the sensors? sounds like a PITA, and the 356s are several hundred bucks. not an item for cheap experiments.
  6. DaveBP

    DaveBP Minister of Fire

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    Thank you, gentlemen.

    I guess we'll have to wait for them to catch on to the needs of what is probably still a minor market in their eyes. Strikes me as a trivial modification to existing products though.
  7. Karl_northwind

    Karl_northwind Member

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    I just noticed you meant the differential controls.
    those might do it. Caleffi has a line of differential controls that can do a lot of different things. you'd install them in reverse, and would want to have a couple other controls, limit controls and such
  8. Bob Rohr

    Bob Rohr Minister of Fire

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    A couple issues with the Caleffi or any Resol based solar differential control. They can only motor down to 30%, still a fairly high GPM rate. They start at 100% speed for 10 seconds. That is quite a slug of cold water before it modulates.

    I believe a tekmar 365 works, if you put a fixed resistor on the supply sensor to "fool" it to thinking about 220F or so.

    I'm not sure that you could run an Alpha or any ECM with a variable speed, PWM signal control however, I'll check with Grundfos.

    Grundfos has plenty of circs that have PWM built in, but only in European versions 230V, 50hz. I have a few samples and they come with two PWM connector wires out of the motor. With enough interest I suspect the solar ECM pumps would be the first to be US ready.

    Here is a possible option for a high flow pump, about 35 gpm, for large 350,000 BTU/ hr. boilers. For smaller flow rates the price of the pump drops considerably, of course. I believe this, piped properly, would thermosiphon during power outages. Thanks to Siggy for the drawing.

    Attached Files:

  9. kuribo

    kuribo Feeling the Heat

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    I have a call in to Taco as well about the bumblebee running in a reverse acting mode. They told me they would call back last week and I have yet to hear anything. Nice to know they are working on it....I will need it by this fall, hopefully it will be ready by then.

    I plan to use it to vary flow to storage to maintain boiler output at a fixed point.

    Thanks for the info.
  10. lotawood

    lotawood Member

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    I'm going to add return temperature protection when I add storage to the 500 gallons that I have already.
    I would use a PID controller, like ewdudley suggested, or this newer bumble bee pump with reverse acting control.
    A year ago I was looking at a reverse delta-T taco 007 for the same price as the alpha. The price of that pump went up a lot. Hopefully the bumble bee wont double in price when they add a reverse feature.
  11. kuribo

    kuribo Feeling the Heat

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    Talked to taco today and they confirmed that the new bumblebee will have reverse acting control and be more powerful. Estimated to become available in the fall...
  12. Coal Reaper

    Coal Reaper Minister of Fire

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    yeah, i can see the BB going up in price. did they mention how much more powerful? or what pump curve it will be similar to? i think i will be near the limit but i hope the current model will be able to move enough BTUs for me...
  13. Pat53

    Pat53 Minister of Fire

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    Same here, I would love to be able to have the circulator either speed up or slow down automatically to send only 190F water into my storage tank, no matter what level of fire is burning. But I need something a little bigger than the Bumblebbe they currently offer. Hopefully they'll make a bigger model too.

    Pat

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