Grundfos Alpha Vs. Taco Bumblebee?

NNYorker Posted By NNYorker, Feb 24, 2015 at 9:48 PM

  1. NNYorker

    NNYorker
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    Currently have a Grundfos 15-58 for my main circulator. My Econo is tied to my oil fired hot water boiler and 30 Gal. Superstor. Three zones - all on zone valves - 1st fl., 2nd fl., DHW-Priority.

    Looking to save some $$ on my electric bill. Both the Grundfos and Taco seem like $$ savers vs. the 15-58. I've read reviews at Pexsupply,et. al. and general consensus is both are good options. Would the Alpha (Delta P) be a better option with my zone valves vs. the Taco ( Delta T)? Any suggestions / recommendations appreciated...........
     
  2. ewdudley

    ewdudley
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    Bell & Gossett Auto, Wilo Stratos, Grundfos Alpha, and other deltaP pumps will work correctly and quietly, and will save power in one-pump-multiple-zone-valve situations.

    The Taco HEC-2 (Bumblebee) will work also, but suffers disadvantages due to failure modes made possible by adding the complication of a temperature sensor, which can fail outright or even unplug itself. For one-pump-multiple-zone-valve applications the HEC-2 offers no advantage. ([Edit:] Which is not to say temperature control, outdoor reset, and variable speed ECM pumps couldn't offer advantages, but now you're talking Tekmar level of expertise, not Taco.)

    Contrary to what Taco marketing pseudo-thermodynamics would have you believe, deltaT control does not increase flow to zoned circuits when it gets colder outside and building load increases. What will happen is that the zones will call for heat for longer periods. The temperature the emitters will see stays about the same since the conditioned space temperature is being controlled to a setpoint, and therefore deltaT through the emitters will remain constant.
     
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  3. varadhammo

    varadhammo
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    Well stated; when I was just learning about this stuff, I had to think long and hard about that claim. It suppose it might provide a bit of a boost when recovering from a large setback though. But I can't imagine it would make much of a difference there either.

    If it's used in conjunction with outdoor reset however, it should indeed slow down when the building heat load is less (here it is responding to the delta between emitter water temperature [i.e. outdoor reset controlled] and indoor setpoint). In my system (zone valves w/ an Alpha), when it's cold out, some zones will run a 10-15F delta. When the weather's mild, those zones might run as narrow as 5F since (Twater - Tsetpoint) is small and there is less heat flux from the emitter. I assume the Bumblebee would slow down in this latter case. But (without having crunched numbers) I can't imagine the energy savings would be very noticeable in real life.

    But the biggest "issue", or at least potential issue, I saw with the HEC-2 in a zone valve application (and why I decided against it in the end) is that all the pump sees & controls is the system's "average" delta T, i.e. the supply temperature minus the average of the zone return temps. That means that for the deltaT setpoint control to make sense, you have to assume that all the zones the Bumblebee is pumping are designed around the same delta T (not always the case). Just my two cents.
     
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  4. ewdudley

    ewdudley
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    Good point, which I had overlooked. But as you say, not compelling.
     
  5. NNYorker

    NNYorker
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    EW & Varadhammo-- I think I will go with the old "KIMSS" ( Keep it MORE simple stupid-AKA-"KISS" ) theory. One less thing to go wrong.....I like the plug-n-play / set it - forget it. In the first couple of years I had a couple of electrical hiccups but after that my system has been pretty bulletproof.
     
  6. maple1

    maple1
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    I can't say much from the comparative/vs viewpoint - but I can say that I really like my Alpha. I have four heating zones & one DHW zone, all with zone valves - the Alpha is a smooooooth operator.
     
  7. jrod770

    jrod770
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    Because I'm trying to plan my system, you have 4 heat zones and DHW on a flat plate all running off of 1 Alpha?
     
  8. maple1

    maple1
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    Yes. Have it set on lowest speed setting.
     
  9. atvalaska

    atvalaska
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    I have my alpha on my main boiler to shop and back run of a 120', speeds 1-3 work like the pump u have now, auto-a ...did not work for me ,I found that "constant pressure 2" was the key to my set up
     
  10. maple1

    maple1
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    Ya, for me its constant p, lowest speed setting.
     
  11. NNYorker

    NNYorker
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    Maple--is this your pump ? http://www.pexuniverse.com/grundfos-alpha-15-55-f-circulator-pump-59896877 It says check valve is optional --I assume one is included inside the box? I called Grundfos tech support and they couldn't tell me yes or no.
     
  12. maple1

    maple1
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    Pretty sure that's it, yes, and I'm also pretty sure it came with the check.
     
  13. varadhammo

    varadhammo
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    Yes, comes with the check in the box. But not preinstalled.
     
  14. mooselake

    mooselake
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    Jan 30, 2010
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    I have both a Taco HEC-2 and a Grundfos Alpha 15-55F in my multi-zone multi-boiler (way to complicated) system. I'm a retired electrical engineer/real time software programmer, which is part of the problem.

    It's a primary/secondary system with the boilers on an injection loop controlled by a Tekmar 356 outdoor reset control. The 356 pulses a (non-smart) 15-42F to control the water temperature in the primary loop based on outside temperature, and there's 6 zones fed by various age 15 series pumps (3 fixed speed, one variable), one with a zone valve. Until a few months ago the injection loop had a propain boiler in series with a 3 way zone valve that switched a Jensen indoor boiler into the loop if it's water temp was high enough. The Jensen (and zone valve) was recently replaced with a w-w heat exchanger connected to an outdoor wood boiler. With dual pumps in the LP boiler and the primary circ there's around 10 pumps in the heating system; don't ask why... Except for the Tekmar and whatever's in the gas boiler, all the controls are relays or mechanical aquastats.

    The outdoor boiler loop is OWB->water heater sidearm->HE->50K garage heater on basement shop ceiling->OWB. The heat load varies considerably based on what's on. This loop has the Bumblebee, set for a 30 degree temp differential, and always on per the OWB manufacturer's recommendation. It spends most of it's time around 11W, bumping up to it's max 41W when it's -20F and the basement heater's running. There's an Azel dual temperature remote reading thermometer sitting in a box, waiting to be installed if the arctic blasts ever leave, so no temp loss monitoring yet. The couple times I put the thermocouple thermometer on it was pretty close to 30 degrees. The sensors are getting a closer look at their positioning when it warms up a bit, since I suspect the return temp is too close to the boiler and reading warmer than it really is. The piping is pex-al-pex and seems to have some insulating value so the sensors are currently on iron Ts with a quick insulating job. Did I mention you should never start installing one of these in the fall before a record cold winter?

    The Alpha replaced a non-smart newer variable speed circ that developed an unnoticed air bubble and died, and is feeding a well insulated basement office with a 4" heated slab (where I'm sitting now). It's set for auto-adapt and from it's display runs at 14W.

    Bumblebee:
    The temperature differential mode works well with it's varying load. Since the flow resistance is constant, unaffected by heat load, delta T looked like the best choice with all other factors equal.

    It lives up to it's namesake, with a high pitched whine that increases with speed. It's on the OWB, no one can hear it scream (except when filling the beast, when it's kinda reassuring), but inside it could be noticeable.

    The sensor hookups are on a push-in terminal block. It was easy to connect, but far too easy to bump and knock loose. When off the pump quits with an error code. I'd consider this a major design defect; it should have gone into full power fallback mode, trading extra power cost for replacing frozen pipes (yes, I have backup, but if this were a single pump no-backup system you'd be paddle-less up the brown creek). As soon as it warms up it's getting hot glued into place. Stupid, stupid, programmer decision.

    With our 25 cents/kwh power cost it pays the difference in price over a stock 80W circ in 12 months, and it's complete cost (I got it locally at higher than the online price) in 24, assuming an average 20W power consumption.

    With only a month of operation I can't predict it's reliability. Online reviews show it's got some early failure problems.

    Programming is tougher than it should be, using long and short presses on a couple buttons. I've got a section from the manual stuck behind some pipes next to it, and despite considerable experience programming similar devices have to refer to it if I change anything. Definitely fails the user interface design test.

    It starts up at full speed for two minutes, then switches into the programmed mode, so it can reach sorta steady state and measure an honest temperature drop.

    It has a constant speed mode that doesn't require the sensors, but still saves a lot of power usage over the old AC pumps.

    During startup while trying to work out the air bubbles it airlocked and said it was running at full flow with no actual water movement. Didn't test that one for more than a few minutes...

    Alpha:
    It's driving a constant flow resistance zone, but since it's only one large room with a very large heat sink that doesn't matter. I could have set it for the lowest constant power mode, but decided to let it do it's thing. It picked close to it's lowest power.

    It's very quiet, not noticeable over low sound level of the other pump(s).

    The fried pump was set at it's lowest speed, 60W per the datasheet. It doesn't run a lot once the floor is warm, so while it'll be cheaper assuming it lasts the 20 or more years like the older Grundfos pumps, it's quite a slow payoff even at our outrageous electric costs. YMMV...

    While purging out the air it also ate a bubble and quit pumping, but it noticed and reported 0 GPM. Also just a short term test.

    Both:
    They both have LED displays showing the current power use and what supposed to be the current GPH, plus a few fixed mode LEDs for the Alpha. The BB displays the current mode in seven segmented letters. The GPM numbers are probably suspect - I'd guess the BB calculates it from rpm, and the Alpha from load and rpm. I wouldn't use either for flow balancing, but they're interesting.

    Overall, both pumps are doing their job. I'm considering replacing my 200W primary loop pump with a bigger Taco delta-t pump if the bumblebee holds out, as it's the fastest payoff of the remaining pumps - although I'm concerned that it may be as noisy, or noisier, then the screaming yellow zonker. I may drop in at least one Alpha on the higher on-time zones over the summer, using the removed pump as a spare to keep the OWB going. In most situations I'd pick the Alpha over the Bumblebee, given the extra cost, noise, and failure prone sensor wiring connection with a freeze your pipes failure mode. The BB can be used as a higher cost higher noise substitute for the Alpha, but without any reliability data it would be difficult to wonder why. In a situation where you can take advantage of it's differential temperature mode, and where noise doesn't matter, it's a reasonable choice.

    Kirk
     
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  15. mooselake

    mooselake
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    Well, despite all the homework I did before getting the Bumblebee, found out that it's replacement is already out from a couple week old post here. Figures; I'm the guy you watch before buying something. As soon as I do the better/cheaper model comes out. Kinda a bummer for the buy local policy, too.

    Supposedly it's quieter, and it has a much cooler looking display with useful things like the measured temperatures. Cheaper than what I paid for the Alpha, based on finding a couple online prices, so it could be a worthy competitor even if run in constant speed mode and the sensors tossed. Might change the equation a bit, depending how it lives up to it's claims. I'll add it to the short list to consider for the next small pump. Like to see somebody else's review first, there's some discussion on Dan Holohan's heatinghelp.com forum.

    They kept the same plug in sensor wire plug, but added a cap to hold it in place, even.

    Kirk
     
  16. NNYorker

    NNYorker
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    Ordered Alpha Fri. delivery on Monday
     
  17. NNYorker

    NNYorker
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    Installed the Alpha today........humming along 3GPM @ 7watts--fixed speed #1.
     
  18. JP11

    JP11
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    I bought two bumblebees.. then promptly bought two more!

    I have all 4 setup on 'delta t' mode. The circ I replaced feeding from wood boiler storage to my 'close spaced tees' routinely runs at 12 watts vs the 79 of the old circ.

    The other 3 are all radiant zones. One does single duty, the other two supply two zones each with zone valves. They run the 2 minutes at full flow (still almost half the power consumption of previous 00R) then kick down to supply water to make a 20 degree delta T.

    I have watched it when all zones are calling, that ALL 4 of the pumps aren't using the total power than just ONE was using with the conventional pumps.

    We'll see what the electric bill does. If the 4 feet of snow will ever shed off my solar panels.. I'm thinking I'll start making some good power with all the snow for reflection, and the direct winter sun.

    JP
     
  19. JP11

    JP11
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    I can't imagine that this March was any warmer than last March. Power usage down 20% I credit the 4 bumblebees.

    JP
     
  20. velvetfoot

    velvetfoot
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    I wish insert fans came with ECM motors.
     
  21. JP11

    JP11
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    In rough numbers.. a month on oil boiler.. 1250kwh, wood boiler 925kwh, now boiler with new circs (boiler still has plain 0011) 750kwh

    I like it.
     
  22. mooselake

    mooselake
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    Now on it's 3rd season the Bumblebee is still buzzing along, and despite the new pump our power consumption is half to 2/3 what it was. Well that's not the BB's doing it isn't hurting anything either. The BB spends most of it's time at the lowest power setting, bumping up in steps to 41W when more zones and the basement ceiling heater kick on. The Alpha's doing it's job as well, but since it's a switched zone it's not full time like the BB. I'd buy either one again depending on where it goes. Actually, mean to get another Alpha or two for the higher on time zones, and use one of their pumps as a spare for the BB, just haven't gotten to it yet.

    Added a Taco 0012 delta T pump this fall, replacing the primary loop's 1/6hp Grundfos. Even set at a 5 degree differential it's activity light pulses once a second or so. No fancy meter or display on this commercial grade pump, the only feedback is how fast an LED blinks. Can't hear it at all, even in the basement. Less noise than even one zone pump. Not sure it'll ever save enough to pay itself back (even at 25c/kwh) but the other pump was pushing 30 years old. The 0012 was a drop in replacement, and since there was a spare set of contacts on it's relay it's switched on/off with 24VAC rather than using the 120V supply.

    Kirk
     
  23. Pat53

    Pat53
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    Mooselake, whereabouts are ya? I'm just NW of Rapid River. I have an Alpha that runs both my zones in the house. Even when both zones are calling for heat, it is using only 8 watts (according to the read-out) and moving about 6 GPM.

    You must have UPPCO for your electric provider? LOL My rate is about 25-26c/kwh also. From what I've read, this is not only the highest rate in Michigan, but close to the highest rates in the country !!

    Pat
     
  24. mooselake

    mooselake
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    @Pat53, missed this until now. I'm south of Houghton in the serious snow belt. We've got the one company that's more than UPPCO, REA.

    Kirk
     
  25. Karl_northwind

    Karl_northwind
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    i have tons of alphas out there and they have been absolutely bulletproof. flawless. bumblebees i have had all the problems listed above, up to and including frozen pipes. i have a few of the new viridian 2218 circs out there and had one go into overheat mode next to a boiler water jacket. a piece of foam fixed that problem. i probably use half alphas and half everything else.
     

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