'A' Rated Pumps.

[lightfoot]

Evening All,

So hands up......how many of you (both DIY & Trade) are now fitting low energy 'A' rated pumps like the Grundfos Alpha Pro or the Wilo-Stratos ECO-ST as standard in your solar and other heating installations.  (Or even giving the customer the option.)

Pumps don't last forever, so when it's time for a replacement shouldn't we be fitting these.  If not, why not, as it may cost less than fitting low energy light bulbs throughout your house.  I wonder how many pumps are being fitted today....right now?

I like to think as more and more consumers start adopting these new energy saving technologies, that it sends a clear message to the manufactures and must surly help to bring the costs down.  Should we have to rely on the government to legislate on the use of low energy equipment as they did with condensing boilers.

Here's some info for those that are not familiar with the (not so new) low energy pumps.

http://www.grundfos.co.uk/web/homeUK.nsf/Webopslag/DMAR-6EGDHG

http://www.wilo.com/cps/rde/xchg/en/layout.xsl/4759.htm

http://www.pumps-processes.com/magazine/news_en/doc3085x.asp

http://www.bsee.co.uk/news/fullstory.php/aid/3641/Energy_Labelling.html

http://www.constructionbusinessnet.com/mechanicalexplorer/news/282.html


Should they be the standard for any energy conscious installer?

 
Lightfoot.

[lightfoot]

From a technical standpoint, I would be interested to hear the views of the Electric-techs on the forum.

What are the pro's and con's of this technology etc?

Do they cost that much more to manufacture?

Are they the future?

What's around the corner?


Lightfoot.

[Paulh_Boats]

Realistically how much power do they save? I estimated that my pump, at 38W, is maybe 2.5% of the power extracted from a 30 tube panel. So with a 97.5% generation efficiency is there much to be gained?

I'm thinking that there might now be a demand for a smart speed controller for older pumps. Full torque for the first 10 seconds, slowly dropping to a user supplied speed.

"Pumps don't last forever" - our Grundfos is 23 years old!

-Paul

[Antman]

Lightfoot

I am undecided at present...

I fitted the Alpha+ on my system last November (only because the original pump started to whine when cold, poor thing). I was not prepared to stump-up over double the cost for the Alpha Pro.

I am disappointed with it as it seems to conflict with the Bypass valve installed as part of the Part-L update with the solar system. The idea of these pumps is to sense back pressure caused by the TRVs closing and throttling back the pump speed accordingly so as to maintain constant pressure (with reduced flow). The problem is that the BPV and pump seems to work against each other and therefore the pump never runs below the equivalent of speed 1. Hence I am no better off (energy wise) than with a standard pump running only at fixed speed 1.

Granted it does improve the flow rate at cold system start - when all TRVs are open. However whilst this improves system warm-up efficiency it is not an energy saving feature as far as the 'pump' is concerned.

Also the Alpha + has a very annoying design feature whereby it always powers-up seemingly at speed 3. Then after ten seconds or so begins to slow down. Therefore  I now have the irritation of a in nearly closed TRVs whever the pump initiially starts up - something that did not occur with a low fixed pump speed.
Design-wise, it would be better if the pump ramped up to the desired speed rather than slowing down from warp drive!
Eliminating TRV noise is supposed to be a feature of the Alpha range - but is completely negated by firing at full speed after power-on. My system never has a requirement to run that fast even at full tilt mid winter! (Speed 2 for cold system starts followed by slow-down to speed 1 or less is ideally what I need.)

Therefore my conclusion based on personal experience of the Alpha + is that it is a double-edged sword. You make system efficiencies in one sense, but you can also end up with unwanted effects. I am not convinced that the Alpha+ pump itself actually saves energy overall.

The Alpha Pro may well work differently and use a different programming control algorithm - maybe others have experience of this one.

I am not convinced that the extra cost of the LED display on the Pro is work the extra money - and there is no reason why the Alpha Pro features (less posy display) should cost any more that the Alpha + model !

Antman

[Paulh_Boats]

Following on from Antman's comments.........   

Modern condensing boilers modulate the pump speed, which will already save power.

From a system control perspective, the smart software in the boiler must be in control of the final speed to do its job properly (load balancing, weather compensation etc). A smart eco pump that works in isolation is not the best control system design for domestic heating.

-Paul

[dinitro]

I have an Alpha+ like Antman

My Alpha+ circulates the contents of my thermal store around the CH circuit.  It is under the control of a boiler
manager and one of the design specs of the system was to remove the BPV.

The effect of this is that the pump runs silent, I cannot hear it going to Warp speed and then powering down!
Percieved energy savings can only be measured if I have an ammeter somewhere in the supply to the pump.

I think the Alpha+ is rated B... the Alpha Pro is A.... though I don't see how an LED reading makes a difference!

dinitro

[lightfoot]

Hi Paul, Antman, Dinitro and All,

The way I see it there are two possible energy saving functions to these pumps.

Going by the data supplied from Grundfos, for any given flow/head output, a standard or 'B' rated pump (which includes the Alpha +) appears (?) to consume roughly between 2 and 3 times the energy than that of a 'A' rated Alpha Pro pump (?).  For example a standard pump set a speed 1 uses say 25 W, whereas the 'A' rated pump uses only around 8 W for the same output, and at position 2 the standard pump uses say 35 W compared to 18 W for the 'A' rated pump.  This in itself has got to be a step in the right direction and it would be good to see these efficiencies on all pumps regardless of any other energy saving functions.

The other function is the ability to regulate it's output to meet the changing needs of the system and therefore consuming the minimum amount of energy.  This is obviously only really a advantage if the system uses TRV's or other thermostatically controlled circuits as used on UFH.  As Paul mentioned some boilers/system controls may already have this function built in, if not then surely a smart pump can only be an advantage.

As for the bypass issue, they recommend the use of a manual rather than automatic bypass valve, which makes sense and is not only cheaper but also one less thing to go wrong, when setup correctly the pump should run at the optimum setting.

I believe the high speed start-up idea is there to help clear any debris and avoid pump seizures, but as Antman mentioned it can go against the principal of reducing the pump output to reduce system noise.

They do seem to be marketing them as a 'one pump fit's all' solution, with the option to set the speed manually rather than using auto-pilot, which is useful for systems not requiring a modulating output, but why not just produce a cheaper 'A' rated manually adjusted pump for this purposes.  I guess as TRV's and alike are becoming the standard now, both here and in other European countries, the use of modulating pumps are becoming more common/necessary to achieve high overall system efficiencies and low system noise.

So I guess any energy saving has got to be a good thing, especially when multiplied by many households.  How much energy they will actually save will still come down to how well the overall system is designed and installed.  Some people will always be looking at the capital/energy payback time to see if they are getting a good return for their cash, so for them the bottom line comes down to price and let's face it their not cheap compared to a standard pump, but the prices do seem to be coming down slowly.

So are they worth the money.........I'll let you decide !

Lightfoot.

PS,  I dare say the LED is a bit of a marketing gimmick, but it may have it's uses for all the data addicts or to rub up the neighbors.

[wyleu]

It's probably more justifiable to recycle an old pump rather than buy a new one, but I don't imagine that's a concept that would sit with most solar end users.

Is the alpha pump really a 3 phase device with electronic control? or have they found another way of getting such an impressive saving?

[Antman]

The Alpha+ appears to be a standard pump casing with a burst firing module. You can hear the 'step' changes in burst cycle at lower 'speeds'. I guess they do something clever with sensing the back emf from the windings, which presumably has some relationship to imposed rotor torque associated with flow impedance.

Well it sounds impressive b*^%%ks anyway 

Antman

[lightfoot]

Wyleu,

Not totally sure how it's achieved as I'm no Electric-tech and just deal with the wet bit, but from what I could make out from their tech guy, it's a combination of hi-tech permanent magnet motor and better fluid dynamics ?  Maybe you could fill in a few blanks for us?


Lightfoot.


PS,  Surly to be awarded the 'A' rating over the 'B' rating of the Alpha +, there must be more to the Alpha Pro than just improved automatic modulation, otherwise it would be like awarding a fridge a higher rating only if you don't intend to open the door very much 

[wyleu]

Single phase motors are pretty lossy, the classic approach is shaded pole http://en.wikipedia.org/wiki/Shaded_pole_induction_motor. The real efficiencies come from a fully rotating magnetic field, which by using 3 phase supply and reasonably simple winding produce a simple efficient motor that will repeat at a multiple ( set by the number of poles used) of the AC frequency. The current consumption goes up as the torque increases but the actual motor speed is very accurate, till they eventually stall. OF course this is great for mains clocks, which are very accurate, largely cos the supply companies are required to produce just the right number of cycles of mains in 24 hours to make this the case. In essence the electricity system is nothing more than a contrivance for transferring the torque from the generator  to your water!.
The difficulties come when you want to modify the speed of the 3 phase driven pump. You can do clever tricks with the windings to get other torque/speed curves but smooth modification of a 3 phase motor is a fairly involved process althou' in this day and age it's probably nicely encapsulated in one control chip and a few triacs.

There are some wonderful high power magnets nowadays, Neodymium, Ion Boron  being a personal favorite and since the whole process is governed by maxwell's equations the stronger the magnetic field used the greater the force derived from a particular current.
Given that the current increases with torque a lot could probably achieved by altering the control slowly from one speed to another, whilst both accelerating and decelerating. Course if you were really going for it you could regeneratively brake the pump when it stops so it puts the energy of the stream back into the mains, but this really does seem overkill.

The traditional central heating impeller is a wonderful piece of kit which manages an impressive reliability in a very hostile environment. Quite how the fairly complex electronics involved will cope with the traditional degree of neglect that impellers experience, is an issue that time will reveal. I'm sure grundfos will have done their homework, but there's probably the odd component that will fail eventually in the early attempts. Expect the copies to be even more error prone.

[lightfoot]

It all sounds like witchcraft to me............some of us have only been walking upright for a fortnight, up here in the mountains. 

[lightfoot]

Some more info for anyone interested  http://mail.mtprog.com/Presentations/Session_C/C4NielsBidstrup.pdf

[Ted]

Also this doc has a bit more technical data:

http://www.mtprog.com/ApprovedBriefingNotes/PDF/MTP_BNDH20_2006December4.pdf

Claims savings of upto 100kWh a year can be made by changing to the newer pumps.

[KenB]

List,

I just bought a Wilo RS 50 which has a C rating.

I'm measuring 30W, 42W,56W respectively for the 3 settings.

Has anyone got any real world measurements for an Arated pump rated pump



Ken