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Grundfos vs Wilo (23 Posts)
Grundfos vs WiloI've been using Wilo for a while now for my zone valves mod con jobs. It works very well. However the set up on it is a bit involved. I was told to come by on a cold day turn on all the zones and tweek the adjustments until I get a delta tee to my liking. In most cases 20 degrees. After that it should be self adjusting. Perhaps I'm being picky but, what if it's installed in the Summer? What if going back is not convenient? How long will it take to really smooth out to a fair representation of the correct delta tee? Time is money. In short, final adjustment to fine tuning is a PITA. I've not used the Alpha yet but the sales line of automatic adjustment is attractive. Not lost on me is the lack of any description on the Grundfos web site as to the parameters of the automatic adjustment. Perhaps I've not looked in the right place, but claims of magic adjustment by the push of a button smacks of a slick haired salesman hiding behind his sun glasses , saying "trust me, it works great," and then flashing me a stainless steel smile. I like the display feature that lets you know the watts/gpm being used real time. Does the Grundfos have the self protection mode that slows the circ down to stopping if all the zone valves are closed but the pump is turned on? I like that Wilo feature. I could use that to turn on the circ by outside temp on a TRV rad system. I want to know how the Alpha "self adjusts." Trust me.
flawlessly operating on AutoAdaptWW,
Yanked out my 11-circ (10-zone + 1-primary) distribution system and installed 3-watt Caleffi ZVs with two Alphas (two temp system) and installed a Caleffi hydro-separator. Hit the AutoAdapt button and forced myself to "step away from the circulators". Might as well toss out most of what I thought I knew about required flow rates. Been in and on-line for this year's heating season and my power reduction is nothing short of having fallen off a cliff; from more than 1,100-watts to under 100-watts when all 10 zones are on and our comfort level was improved, which was tough for me to believe having what I'd assumed was a creme-of-the-crop radiant system using hi-eff & outdoor reset.
Here's the thing: the outdoor reset curve immediately skews the run-hours, which simply means longer run-times for zones/circs and multiple zones compound the issue. I slashed my operating costs. Data-logging with a Kill-a-watt meter - both before & after - to get accurate data.
Don't much care if it's to be D-P or D-T - ECM technology is here to stay. Soon we'll have a new player with their own ECM version.This post was edited by an admin on February 27, 2010 10:22 AM.
InfoWW, Grundfos's site is misleading. You would think they are selling cars or sports apparel
or something. If you are diligent and poke around there long enough you can actually find useful information. Look for a link to a white paper written by the engineers who designed the algorithms .bob
White paperWW, try thisbob
thanks for that bobinteresting reading.
so does that mean if you use on/off zone valves with a proper reset curve (i.e., they are open most of the time) that the pump will keep trying to increase its pressure output in autoadapt mode?
I'm thinking teknet 4 systems, where it's shooting for minimal temps using indoor feedback. It will work to "saturate low" aggressively. Meanwhile the alpha sees that as a sign that its speed is too low? ouch.
I guess it's good that its max power usage is still 50% lower than normal usage. but that's not ideal for any indoor feeback on/off systems, it seems. it's good, worth using, but not as optimized as it could be.
Not sure that will happen...Conflicts due to scheduling pumps per the Tekmar algorithm may happen - the Grundfos system is likely best suited to analog valves that open proportionally based on need. However, I'm not convinced that the alpha would necessarily get confused as described in your post. As I see it, the unit modulates until the area described by the green line above and below the median (black) line is even. The tekmar staging valves may interfere a bit but the Grundfos has been designed to operate on systems involving potentially dozens of valves (i.e. an all radiator system with proportional valves) and hence is likely designed to work around rather strange flow conditions.
The good news is that if you find the alpha alogrithm to be wrong, you can still set the pump to operate on a simple Δ-P basis, dial in one of three heads, and call it a day. I believe the Wilo ECO gives you more options re: head pressure but the benefits of a permanent magnet motor with Δ-P feedback are the big features for either pump.
it's trueI just lose the bottom 6 watts off my power draw curve if I leave autoadapt :(
still, it's good that the hairsplitting here is based on fairly low power differences. it really is a new day in residential pumping for both Wilo and Grundfos.NRT.Rob
Thanks BobI just finished reading it too and unfortunately it didn't do the job for me. They say it works because of the algorithm. Well duh! They could just as easily say it works because it's magic and the message would mean as much to me. I need a talented communicator to put things in English and in layman's terms. If Grundfos wants to hire me to speak for them and teach me how it works I'm sure I could do it. Most engineers are not good communicators and should be held responsible for that deficit in their abilities.
AlgorithmWW, my take on autoadapt. If you look at centrifugal pump performance curves you will notice that the H.P. ( current draw) curve parallels the head/gpm curve. All the alpha measures is current draw and time. They equate K factor with current draw. As zones open current draw goes up, as zones close current draw goes down. By recording variations in current draw over time the microprocessor makes a SWAG at a system curve. As current draw decreases the pump rpm is reduced so that the pump curve shrinks and the pump operating point follows the SWAGed system curve. In my lexicon
SWAG is a synonym for algorithm. The feedback I'm getting is that it works pretty well, it tends to kill the noise in micro-zones. Does any body know what units K would be expressed in?bob
well, a little more on thatI was getting from the paper that it records the range of draws, and watches how often it is at the top or bottom of the ranges. If it's at the bottom draw too much, meaning zones are off a lot, then it adjusts itself to run slower to keep open on longer. If the zones are open a lot, then it adjusts to run faster to try and close the zones a little more often.
If i'm all wet on that, great, but if not, that means reset curves of any kind prevent the pump from fully optimizing itself... they would all top out at the top end of the power draw curve (45 watts) even if they could have, say, maxed out at 30 watts instead.
would be nice if you could adjust it for "reset" operation.NRT.Rob
"would be nice if you could adjust it for "reset" operation."I'm not too familiar with the Wilo circulators, but resetting based on the outdoor temperature is attainable using only delta t as I see it. Isn't variable speed most beneficial to the system operation if temperature is the measuring factor?
Small or large zones combined have virtually no effect on system performance if only DP are measured given the variables in emitters right? Maybe I am not seeing it, but that far away micro zone opening while others are running may increase flow from the pump but to what disadvantage to the other zones that were optimized before the micro zone opened?
I think we've got a true game changer when we see a ECM DT circulator hit the market. For now its one or the other. One way is definitely not clear to me if it is even the right way to control flow. The other is definitely an improvement over existing technology but not yet as efficient?
"If you don't like change, your going to like irrelevance even less"
what I mean isI wish I could tell the pump "hey, most of my zones are SUPPOSED to be open most of the time, don't speed up if they are", that's all. since I have water temp shift already I don't need the pump to increase as well.
I am splitting hairs at this point, of course. I suppose the next step would be simply a 0-10 input, and for controls with system pumps to start modulating pump speeds along with water temps. I know the commercial boys get that sort of operation.NRT.Rob
Taco Bumblebee?I'm looking for an efficient (ECM?) dT circulator for my 1 zone (maybe 2 zone) radiant floor system I'm installing. I plan to use a 4 way mixing valve with outdoor reset control on my cast iron boiler...
I keep trying to decide about the Wilo or the Grundfos but the Bumblebee seems ideal and I can't find out if it's available yet... (assuming no?)
BumblebeeLast I heard it was supposed to start shipping in quantity during January 2013. It's the only ECM pump with true ∆T operation (though I'm not convinced that ∆T is actually the best algorithm in many applications.)
Wilo has a temp sensor in the Stratos, and while (despite multiple conversations with people at WIlo) I don't really understand the algorithm, their auto day/night mode seems to work quite well with ODR.
the algorithmis posted lower in this thread: max head at max flow, half head at zero flow, line between the two.
I just went around with my local wilo rep trying to figure out why the heck I would want to cut my HEAD in half just because I had zones closing... I design for a given head in each zone, and I need the same head in each zone whether other zones are open or not.
However, in applications where your COMMON PIPING is a significant proportion of your head loss (mixing valves, heat exchangers, small common pipes, large zone counts with lots and lots of flow maybe) then as zones close the head in the common piping drops and you don't need as much.
so this is how I would use these pumps:
1. If you have significant losses in piping that is common to more than one zone, use the "variable pressure" mode on WILO
2. If you do not, and have multiple zones, with reset water temps/long on times, use constant pressure modes on WILO or Grundfos
3. If you have multiple zones with fixed water temps, then AutoAdapt on the grundfos can be ok. I'm not convinced it's necessary though and would probably choose constant pressure still for predictability.
4. For single zone systems, or systems where you are designing for the SAME delta-t in all your zones, then Delta-T based operation is great. might be Bumblee time in that case.
I can't believe Taco is releasing the bumblebee without a constant pressure mode. I am really bummed about that. I guess they are assuming that everyone designs for a constant delta-T in all their zones, which is really unfortunate. I'll definitely look at and use it for delta-T apps that aren't large enough to need Stratos sized outputs, and I have some, but man. they could have nabbed it all if they had constant pressure instead of fixed speed as the fallback setting. ah well.NRT.Rob
taco responsenot sure if this answer's Rob's point: "the bumblebee does in fact allow for a fixed speed mode as noted in the instructions. It also allows for a fixed temperature and a delta t mode of operation, those among many other options make this an extremely versatile pump."This post was edited by an admin on December 7, 2012 12:08 PM.
yesthat's fixed speed, not constant pressure. If I run at a fixed speed, it doesn't change speed based on pressure (i.e., how many zones I have open). Fixed speed is how all normal non-modulating circulators operate.
the delta-T operation in a residential circ is nice. but for me to use it I have to nearly double my total system flow rates which would both strongly reduce the benefit of using ECM in the first place, and would also increase the number of pumps I need on most systems.NRT.Rob
answer?2nd response: "There is a third setting on this pump called set point, which maintains a fixed temperature (not just a fixed speed); the setting varies the speed to maintain the temperature at a certain point."
Someday I'd like to use a circ like this in my home; if this answers your issues then perhaps it's not clearly stated enough in their instructions.
hehyes, I'm not sure exactly what set point is supposed to be for unless you're using the pump as an injection mixing device.but it certainly is not a constant pressure mode, and not helpful on any system using reset water temperatures... as they all should be ;)NRT.Rob
algorithmiaI do understand the ∆P and ∆P-V modes. ∆P is a better fit for most of what we do, since we work hard to minimize distribution losses and use reverse returns wherever possible. The night setback and ∆P-T modes are still somewhat of a black box. One of the great attractions of the Stratos line for us is the BACnet option. Grundfos is still stuck on GENIbus, which adds extra work and costs.
I also believe the BumbleBee needs a pressure-dependent mode. I just don't see how ∆T can respond properly to an armload of zone valves located downstream of the pump. It's ideal for a boiler circ or an indirect, but they do need some additional size options. 008 hydraulics are not really ideal for either a short boiler loop (though it might work with something really restrictive like a Giannoni) or an indirect.
Swag = AlgorithmNow that makes sense to me. I know what a SWAG is. Thanks for helping me understand.
Glad to help... :-P... and even gladder to see/hear you're feeling better.
N/A March 25, 2010 @ 3:39 PM
ECM - how do it do dat?Not a fan of algorithms either. This is how I train on ECM and delta PV...
Motor windings have a rolling magnetic field when power is on. The permanent magnets in the ECM rotor "grab" the winding field and spins.
The "brain" "sees" the relationship between these two magnetic fields and knows when there is a flow and pressure change (as it changes the rotor/winding relationship). If more flow is seen the pump speeds up and the delta pressure is increased (cool cause the friction loss increases at the same time).
Delta PV means if the ECM pump is set at say 14 feet, that is 14 feet at max speed and exactly half of that at zero flow (or 9 feet). Because of this inclining performance curve it will 99.99% of the time run perfectly, regardless if it is fired up when it's warm or cold.
The built in automatic setback function is cool too...