Does efficiency of circulators really matter much?

Jean-David Beyer

My heating system uses Taco 007 circulators that do not use lots of power compared to other things in my house, but now that I have a mod|con boiler with outdoor reset, they run a lot of the time, so I care some about efficiency.



I have seen on the web that ECM circulators can cut the electrical load 50% to 80%. Let us assume that that is true. At first glance, it seems that, capital cost excepted, one would think it obvious that all circulators should be changed over to ECM versions.



But looking at something like a Taco 007, where does the heat produced by the inefficiency of the circulator go? The entire circulator is cooled (and lubricated) by the very water used to heat the house. So it is not as though the heat caused by the inefficiency of the motor is wasted, since it is used to heat the water. It seems to me that the waste is only due to the higher cost of the electricity vs. the cost of whatever is heating the boiler, no doubt gas or fuel oil. In other words, the efficiency increase provided by the ECM type of motor is is not all pure profit, though some of it is.

Dave Yates (GrandPAH)

depends, but I'd vote yes & here's why

As you noted using ODR increases run-times. With multiple zones that can often mean the primary loop circ is on 24/7 during heating season. But, let's assume the following:



3,800 circ run-hours / 87-watts for the standard circ / 10 watts on average for the ECM circ



I'm currently at 11-cents per kWh, which translates into $36.37 vs. $4.18



Next year we get deregulation and, which will bump us up & I'll use 16.5-cents per kWh for this example. That translates into $54.55 vs. $6.27



Might not seem like a big deal, but after adding an annual 5% increase in cost for electricity, I'm only looking at a 4-year payback in the cost difference between the two circs! Over the course of 20-years, I'd save $1,506.58.



Now - consider my savings with a 10-zone system by installing two ECM circs (2 temp system) along with 10 3-watt zone valves. Anticipated cost savings over the same 20-year time-span = $17,609.98



Nice to see all the major players now offering ECM circs.

Jean-David Beyer

regular vs ecm circulators.

I agree with you, as far as it goes. Let us assume your numbers. A regular circulator uses 87 watts (probably what my Taco 007's require), and an ECM circulator takes 10 watts. That means 77 watts are lost due to inefficiency, but the 77 watts are turned into heat, and that heat increases the temperature of the water, so I burn (in my case) less gas to heat the house. So in a sense, I am using the inefficiency of the regular circulator to heat the water.



So, since 77 watts = 262 BTU/hour. If I run 3800 hours per season I use 262,600 watt-hours and generate 995,600 BTU. Say 262 KWH or about 8.94 therms. I pay about $0.19 per KWH (including generation and delivery) and about $1.31 per therm (including therms and delivery). So $48.78 for the electricity wasted (cost) and $11.71 in gas saved per heating season of 3800 circulator hours. So if I fail to replace my circulators, I waste about $37 per year per circulator.

Unknown

Interesting angle,,

I had never really thought of that before,, but it does make sense electrically speaking.

Unfortunately, that outlook does not help our "environmental footprint" much.   

Dave Yates (GrandPAH)

not quite how that works

The circ's shaft is hollow, which allows water to enter and surround the motor's winding housing (can). The only movement out of the 'can' to carry away waste heat is via thermal expansion of the water and conduction through the impeller's housing. The water doesn't circulate through the 'can'. As a result, the waste heat generated radiates away from the body and also via convection to the surrounding air-space where the circ is located.



That's why they shouldn't be installed standing on their heads unless system pressure exceeds 20-PSI.



But, even if that waste heat were to be captured and put to work, the ECM motor would still kick it's butt for efficiency. Nice to see the thermal bridge between source and emtter become a strong link in the efficiency chain.



1 week left to name the Taco ECM circ and win that Smart Car! 

Jean-David Beyer

Go to extremes to find weak points.

At least when think about something. I am not suggesting to try it physically.

Imagine I get a 50 KW circulator that runs at 20% efficiency. Then it produces 40 KW of heat which well might heat my house with no boiler at all. My previous calculation shows that this is more expensive than burning oil by a large margin, so it is a dumb idea.



My previous suggestion, however,  is not good for a Taco 007 or related circulator or related designs in any case because, as Dave Yates pointed out, there is essentially no flow of water through the motor section of the circulator. There must be a trifle, to ensure that water can get in and air can get out, but that would be nowhere near enough to get a useful amount of heat out from the motor and into the circulating water.



I cannot tell from Taco cut-away drawing if the motor shaft is hollow or not, but it does not change the arguement.

Dave Yates (GrandPAH)

R&D - idea floated years ago

Prior to ECM circs hitting the streets of hydronica, (About six years ago.) I met with the R&D dept of one circ mfgr and suggested they capture that waste heat with a cuff that could be retro-fit over any circ on the market. Plenty of materials suitable and the retro-fit could be accomplished with either new flanges or a new style gasket between existing flanges. It was discussed at great length, but they felt there were too many potential issues involved for little gain in efficiency. As it turned out, they had ECM circs in their R&D labs undergoing rigorous testing, which dramatically shifted our conversation's focus. I agree with you that it's not a bad idea. It's just a bit too late in the game as ECM technology is going to sweep the PHVAC electric-motor industry.



My own two ECM circs paid for themselves in my first year of operation. If I had charged myself standard installation rates for my system's energy-conservation-makeover, I'd be looking at a 4- to 5-year payback - with no small part played by deregulation of power rates starting Jan of 2011. Predictions range 37% to 80% for the hit we'll get.



ECM technology presents, I think, a game-changing moment in our trades. Modcon technology gave us an average boost in operating efficiencies of 30%. With ECM, that's more like an 80% to 90% boost. My own home's boost was a shade over 90% after two years of data-logging.    

EricAune

Respectfully disagree

Unless you are switching your ECM's for each heat call, the savings you are stating are likely overstated.



I have no idea how your system operated, I am sure however that it is top notch and exemplary.



Most retro fit situations do not find themselves candidates to lower operating costs as significant as your numbers show.  Most systems switch the pumps on and off with a call for heat, these circs were designed for constant power and, therefor, consume energy while idle where a 007 (example) does not.



If you calculate the amount of energy an ECM circ consumes while idle and when working and compare to a switched 007, the savings are far less extraordinary.



This explanation says it more clearly (consider the source, I have and trust it):

http://jbblog.flopro.taco-hvac.com/?p=464 

Jean-David Beyer

I have no idea how your system operated ...

" I am sure however that it is top notch and exemplary."

I do not know if it is exemplary or not, though it seems pretty good. I am switching heating contractors because the one I chose to install the system seems to do pretty well at installation, but their service leaves a lot to be desired, unfortunately.



My system is partly primary/secondary and partly not.



The boiler has an indirect hot water heater across the supply and return, with a Taco 007-IFC circulator. This runs when the water heater is unsatisfied, and is off when it is satisfied.



Above that is a boiler circulator (a Taco 007) that goes through a flow check valve to two closely spaced Ts. So except when the water heater is running, the boiler sees primary/secondary operation.



On the secondary side of those closely spaced Ts are two Taco 007-IFC circulators, one to each zone. One zone is radiant at grade slab. The other zone is two rooms with 14 feet of Slant/fin in them. Each of the circulators is controlled by thermostats in the zones.



So any change I might make would be called a retro-fit situation. I guess if I change anything, I might swap out some of the circulators. But which ones? I guess I could replace the two zone circulators with one delta-P circulator and two zone valves too.



1.) Since the indirect water heater runs only 10 - 20 minutes per day, and its circulator is off the rest of the time, I doubt it makes any sense to change out that one. (Priority 1)



2.) The boiler circulator (the one in the primary loop) runs the longest, since it is on whenver either or both zones call for heat. So maybe I would change that one.



3.) The radiant heat zone runs the longest; I tried to diddle the reset curves so it runs almost all the time, and it does that sometimes when it is very cold out. So it makes sense to change that one out too. (Priority 2)



4.) The upstairs zone runs maybe 4 hours a day. Not enough to matter, though more than the hot water heater. (Priority 3)



The ECM circulators I have seen on the Internet all seem to be variable speed, and I do not believe I need that feature (unless I convert from circulator zoning to valve zonng). The thing is that these circulators seem to cost around 5x the regular ones, and would take 5 years or more to pay back. I have not decided what to do yet.



I wonder how difficult it would be to switch circulators. It they have the same mounting flanges and the flanges are spaced the same as the 007s (I have not looked this up, but I assume the numbers are available), it would be pretty easy to swap them out, but anything more complicate I would need a professional to do it, increasing the time required for payback. And what would I do with all those slightly used regular circulators? I already have a nearly-new one from my old boiler that I am keeping as a spare.

Dave Yates (GrandPAH)

I do too - mostly

However, the blog article has some info that's not accurate. The D-P ECM circ can, in fact, be left "plugged-in" 24/7, but that wouldn't be my choice for the typical system. In my case, I installed a duplex receptical and split the two outlets to be turned on/off by my zone relay box (5-watts for the zone panel and that's included in my kill-a-watt metered monitoring). I've rarely seen 30-watts or usage above that rate (5-zones per ECM circ - 2 circs & 10 zones) and more often than not, it's well below 20-watts. Real-world vs. theoretical. Seeing watts below 10 is also quite often seen with 6's and 7's not at all uncommon. No 5's in my system as that's the no zones calling condition if the circ is left plugged in.



If I hadn't been using a beta-test model (since returned), I'd have cut the cord and hard-wired the circ instead of using the duplex receptical. Black, white & green jacketed wires inside under that black cord & it doesn't get any plainer than that for simple 110-V wiring.



The run-hours need to be extended when using ODR. SE PA lists 2,250 run-hours for standard it's on/off non-ODR equipment. As I expected, my ODR curve greatly increased those on-cycles while virtually ensuring the zones circ (or a primary circ) ran pretty much 24/7. Once you take into account the extended run-times, the cost disparity widens as I listed for my home above. Our heating season is also longer - 7- to 8-months with the shoulder seasons included.



I get the argument. We aren't talking about huge sums of money over a short-term look at the system's efficiency. However, as our systems have become more efficient and the low hanging fruit has been harvested (boilers/furnaces/heat pumps & A/C equipment along with the delivery side) we're left with a low-efficiency transfer-bridge. The HVAC industry is embracing ECM blowers and not giving installers the option to use PSC motors and no one, it seems, is debating the energy savings vs. cost to use the more efficient technology! As time moves on and consumers become more attuned to parasitic energy consumption, these smaller bits of fruit will loom larger. It is our job, I believe, to be responsible for giving our customers the option to spend a bit more green up front to keep more of their hard-earned green as the years pass by and power rates continue to climb.



DT or DP doesn't matter to me so long as it's ECM-based. There's an argument where we'd be picking nits(G).   



 

LarryC

What about susceptability to Electrical problems?

I would like to bring up the point that shown up with the mod-con systems.  Equipment failures due to lightning strikes and other electrical problems.  I agree that saving $50 a year is great, but for those who live in areas that have a good number of thunder storms, lightning strikes, and general power outages, the reliability of the electronics is a major concern to me.

I plug my PC and TV into a surge suppressor.  How do I plug in my circulator?

When you as an heating professional goes to replace an ECM circulator, do you ask about surge suppression?  Should you?  Do you cover this as a warranty replacement?

I assume replacing a surge damaged circulator will greatly extend the payback period.

Larry C

NRT_Rob

respectfully disagree with your disagreement

you can switch the ecm pumps off and on like normal if you like. However doing so, means your transformer in your relays is probably going to draw the same kind of "ghost load" the ECM pump would in idling. I still like zone relays for the nice little lights, but I think it's a wash, power wise. unless I"m wrong about the ghost draw of a transformer, which I may be, I haven't metered it myself.



I do disagree with dave's estimation: 87 watts to 10 watts is a bit extreme. I think that might make sense for zone pump replacements where the modulating ECM nature really kicks butt, but typically the circs I'm seeing can use about half the energy of a comparable non-ECM pump for the same work. they modulate of course, so in his example I would call a typical situation more like 87 watts to, say, 25 watts or so.



A typical non-ECM pump can run up to 65 KWH/mo if it's on full time. you can save about 40 of that then, or some fraction of that based on run time for the kind of system you are running, from constant circ to high temp bang-bang (most to least).



what I'm generally finding is that the economics are very good if you are replacing a bypass valve. If you drop the relay on a multi-zone system as well. both, even better. but if you can't drop any hardware, you're "greener", but payback is very poor.

CMadatMe

How About

Everyone seems to be focused on electrical usage. Doesn't the adaptation to regulate flow also play a part in the savings? If I can consistently maintain the best flow rate for the best heat transfer doesn't this savings fit into the equation. I guess the question I have is. Does delta-t influence system fuel savings? Where as a 007 may be pushing a 8 to 10 degree system delta-t the Alpha (as example) may give me a 12-15 degree delta-t. Flow does influence btu output of baseboard for example.  

Jean-David Beyer

Equipment failures due to lightning strikes

My mod|con is wired direct to its own circuit breaker in the power panel. Since there was no easy practical way to use a computer-style UPS and surge protector in there (maybe someday), I had an electrician install a whole-house surge protector in the power panel. It does not provide as much protection as I might wish, but it sure takes the larger peaks off the incoming power. I hope it is enough. Since my current circulators are just circulators, there is no electronics there to deal with. I do worry about the control board in the boiler, though.

Dave Yates (GrandPAH)

Rob - interesting

Good observation Rob. However, in my case I previously had 11-circs and 4 zone relay boxes - each with its own transformer. In order to eliminate the zone relay box transformer I could utilize non-electric thermostatic valves and leave a DP ECM circ plugged in 24/7. I chose to use Caleffi 3-watt powered-on zone valves instead, which I connected to the new zone panel box that draws 5-watts. I tranny instead of 4. Saves a whopping 5-watts over plugging in and leaving on the two ECM circs, but also eliminated the watts previously used with four seperate zone relay boxes.



Sure would have been simpler to design from scratch rather than doing a retro-fit!!!



87 to 10 is not extreme, in my case, because of the smaller zones. Easy enough to determine by turning on just one zone at a time in order to monitor each zone's energy draw. More than a few consistently operated below 10-watts while being able to maintain comfort-settings. The ECM's ran closer to the numer you suggest only when all, or almost all, zones were actively calling for heat.



Woulda had a hard time believing too without having had the first-hand experience of living with the new technology.

Dave Yates (GrandPAH)

just another fuel

Over the past decade, we've begun to incorporate cost savings - or potential to reduce costs - by upgrading to high-eff equipment. Unitary equipment incorporates things like ECM blowers and variable speed drives - like inverters. Same for multi-stage HVAC equipment. Squeezing efficiency from all angles. ECM simply comes along as part of those packages.



Hydronic systems differ in that they're field-assembled using components from a wider number of manufacturers, rather than arriving as a complete system. ECM technology is now granting us the ability to slash parasitic power consumption.



Flow rates do play a role, although I personally think that's to a much lesser degree in residential apps where watts are being used. Moving more GPM would need more energy. If I can satisfy a zone using 7-watts with a DP and 10-watts with a DT circ, we're really beginning to pick nits. If both provide the same level of comfort, then I am just happy we're moving to ECM motor technology. In my mind's eye, I can see apps where each style would be appropriate and others where either is suitable.



It would be interesting to operate a multi-zone system for a year with one type and then swap out to the other to gauge the overall performance re power consumption. Lots of other criteria would need to be monitored in order to ensure an apples-to-apples comparison. Might actually require a test lab with steady-state load-demands to ensure the playing field is level and fair.  

CMadatMe

I hear What Your Saying Dave

But isn't the principal behind an ECM motor in a furnace to just increase motor speed as the return filters begin to clog with dust to maintain that units designed CFM. From speaking with a furnace manufacturer the electrical savings isn't as big as one may think. Actually once that motor starts ramping due to a filter beginning to clog that savings starts to really diminish. How many homeowners change filters when they are suppose to? So, I really think an ecm motor has more of a savings effect in an hydronic application than any other.



Most of us were taught that the best way to zone was with pumps. With the ecms I'm really beginning to feel that the best way to savings as far as zoning goes, is to zone with valves utilizing an ecm pump as a system pumps. That includes zoning valves on indirects providing I am sizing my domestic needs and load properly. 

Dave Yates (GrandPAH)

ecm

While it's true an ECM blower can automatically compensate for restrictions via dirty filters and undersized ducts - within tolerances - they can do much, much more and their operation is more eff than a PSC motor. they're moving air, we're moving water - but both are really moving thermal-comfort-energy.



Just came from a class today on a Canadian geo mfgr - Geofinity - and the filter change need can be programmed to send e-mails. It's ECM blower reacts to lots of sensor-inputs to compensate for many different things while squeezing out added operating efficiency. Adaptive intelligence on board. A few years ago, I'd have had a different reaction, but today I embrace these changes because of seeing how well mini-splits operate with the higher-level of adaptive intelligence. Much as I'd love nothing more than to return to the days of standing pilots and thermocouples, that's the past and we're headed into the future at speeds that can be disconcerting and more than a bit uncomfortable while we grapple with the knowledge that much is being wrested from our personal control and being managed by mirco-computer chips. It is indeed a brave new world.



I was, just a few years ago, a dyed-in-the-wool zone with circs only kinda guy. My aversion to zone valves could be traced back to the 70's & 80's when they failed with great regularity while circs ran like the energizer bunny. Radiant heating and telestats began to change my mind-set a bit. While I still favor circs, more than a few of today's zone valves offer similar reliability, are simple to install, can be changed out rapidly, are not expensive, and conserve power - like the 3-watt Caleffi ZV's I decided to incorporate that operate like a telestat but can be installed on either the supply or return.



One thing is certain - change is constantly changing and we need to stay abreast of the evolving changes. Who knows - in a few years we could be moving water with sound-waves while minerature micro bits of nuclear fuel power our heating & A/C systems! I look forward to whatever changes we'll see. Hoping for solar to win the day as time goes on and the folly of continuing with fossil fuels becomes blatantly apparent.    

CMadatMe

Same Path

I really here you on the changes. I don't think our industry has every seen the changes come as fast as they have in the last few years. With the every changing technology in this computer age we all need to adapt more reactively to what has come out and is on the horizon.



What once was a fight in new product technology change has now become a reactive and adaptive change. Those that take the fight will now find themselves out of business where as years ago they could just coast by. I think that the science of the new technology though is harded to justify as we adapt the science to old and unkept homes. It's much easier to apply new technology to homes that are built today and those home that are maybe 10 to 15 years old. It's a real tuff battle to apply todays technology to all those much older homes that we all experience everyday to justify the added cost for the new technology.



The need for a new business is greater today than it was yesterday, That new business would be to incorporate home energy audits into our businesses to help homeowners with long term solutions instead of short term solutions. Instead of being installers of products we should be energy consultants that install equipment and products. I think that is the future of the industry as a whole. It may come sooner than we all think. I believe the new energy rebate bill past the house today and is on to the senate. If that passes it opens up a whole new avenue for all of us.

Jean-David Beyer

Luckily for me, I am not in the business ...

so I do not necessarily need to keep up with the technology. But I was in the computer and digital system business most of my working life, so it does not scare me. I actually am of two feelings about technology.



In favor, because it permits more efficient products that save energy doing whatever they are designed to do. In favor, because they can lower the maintenance costs. In favor, because they can lower to costs of operation and maintenance.



Opposed, because things become ever more complicated, so the opportunities for failure become greater. Opposed, because they "dumb-down" the quality of the people needed to operate the things. Opposed, because the manufacturing of the things is more automatic, and that tends to cost jobs. Opposed because they are more difficult to understand in detail.



Consider a few more modern inventions. Steam locomotives could be built and maintained by people with an 8th grade education, and needed a highly qualified engineer and fireman to operate. Most of the parts needed to ba accurate to only about 1/100 inch. Electric and diesel-electric locomotives need a lot of stuff made to 1/1000 and 1/10,000 inch. They have far more moving parts. They cost a lot more to make. And the labor to operate one is less. They do not need to be checked out every 100 miles anymore. They do not need a crew to lubricate the bearings and blow them down every 100 miles or so, etc. They are much more capital intensive, but that is good for the railroads, but not so good for railroad workers.



Consider wrist watches. They used to require extremely skilled specialized machinists to make them, one at a time, and the best of them were very very good. And they cost a lot. Now an automatic machine, or child labor, can make them about as fast as cookies. People often throw them away rather than going to the trouble of putting batteries in them. I am not sure, but I would imagine the skill necessary to make a traditional (formerly traditional) watch is passing from the earth.



The list could go on, but you get the point (though you need not agree with it).

hot_rod

a chicken in every pot, a circ on

every radiator. Add this small POI point of use circ to those Jaga high efficiency ECM fan radiators and behold low energy fluid and air moving. Or the larger central ECM circ with TRV's. From the Mostra show in Milan, Italy.



hr

NRT_Rob

I can't wait

for 24v pumping. *drool*

Unknown

ECM Efficiency

Gents, I am watching this post thread with great interest for sure (Hot Rod, how did you like our little 24 volt 1 watt circs - cool eh!).  We launched in Germany this spring.



Regarding the "thermal efficiency" of a water cooled wet rotor circ, I have fought that battle for a few years now.  Line to water PLUS thermal (the fact that a wet rotor circ DOES help heat the water) should be the rating of all wet rotor pumps.  But bare in mind, only 30% of the heat is water dissipated, 70% is air cooled.



Energy savings of ECM is the "typical it depends" answer.  At full speed and BEP an ECM pump is more efficient than a standard wet runner due to the permanent magnet rotor but not much more than about 15 to 20%.  At low loads and low flows is where the huge savings come into play.



Electrical savings (assuming 4,000 operating hours & $0.08/kw):

Standard circ: 90 watts/1000 x 4,000 hours x 0.08/ = $28.80/year

ECM circ: Average 20 watts*/1000 x 4,000 hours x 0.08 = $6.40/year

* wattage is based on system load profile (% operating at full output, % at 75% etc) and is dependant on the location and how over-sized the system is.



Most systems run below 50% output most of the time.  I crunched some numbers and if all pocket circs in the USA were ECM that would save annually the equivalent power that 500,000 homes use in one month! (1,400 tons of carbon emissions saved annually).  PLUS, remember every kw of electricity produced in the USA CONSUMES 2 gallons of water to make it.  Trust me DOE is very interested in these numbers.



Note average electrical cost in USA is $0.12/kw (not $0.08/kw).  Electrical costs WILL go up soon.  And these savings do not include increased system efficiency nor fewer components (no by pass).



Regarding surge protection, ECM is soft start but the protection in residential circs is similar to standard pocket circs - impedance only.  Commercial ECM has all kinds of overload protection built in (over/under voltage, dry run, locked rotor, over temp, over amps etc).



Stay tuned guys.  AHRI (IBR/GAMMA) has a new "Fluid Pumps" section and we are looking at all this stuff to be able to provide a circ efficiency rating so you won't have to do the math.  Kind of like AFUE for boilers.  More to follow for sure.

LarryC

ECM reliability

With respect to the ECM pump reliability issue, what I am most concerned about are the electronics.  As the physical size of the solid state devices get smaller and smaller, they become less tolerant of abuse and non-design conditions.  I understand that things are getting smaller, smarter, and faster,  I just don't know if the reliability of the electronics are at the level they need to be, in order for wide acceptance into the market place.  Once the ECM pumps have a proven history in the market place, and people use them where they are an appropriate choice, I belive that they will make a better choice than the existing single speed circulators.

I recognize that I am biased towards "trailing edge" technology.  I prefer a proven, reliable, robust system rather than the latest and greatest.  I also prefer systems that work when I need them.

Kevin Koenig_4

24vdc pumps

  A 24vdc ecm pump is available now.  http://lainginc.itt.com/files/LTSS-28.pdf

 I am curious to know if there would be much interest in zoning with pumps similar to these if the cost of the pump was reasonable.  It seems to me that decentralized pumping in north American architecture would be unpopular for a variety of reasons. Difficult acess to pumps. Lots of wiring tampering,etc  For these reasons I think most installers would prefer to have all there pumps in a common location. If the pump speed was manually adjustable then each of the circulators could be dialed into the best speed practical or possibly use delta t control on each zone to keep the watts down. I would estimate that ecm zone pumps would run in the range of 10-25 watts each for an average three or four zone system.  Certainly more power than zone valves but still a lot better than PSC motors. So, is it likely zoning with small  ecm circs would gain any popularity.  Kevin