Delta-P/Delta-T Part #5

CMadatMe

It's getting more interesting. Come on guys haven't heard back from you in a while. Sure sounds fair and accurate.



<a href="http://jbblog.flopro.taco-hvac.com/trouble-boys-2/">http://jbblog.flopro.taco-hvac.com/trouble-boys-2/</a>

SWEI

I'm just curious

how much of this is attributable to differences between minimum pump curves as opposed to control strategies?



Even smart circulators must be properly sized.  Wilo, Grundfos, B&G, and Taco all offer a single "residential" smart circulator, and all have similar hydraulics.  The situation improves for light commercial applications, with both Stratos and Magna offering a reasonable range of sizes.  We need some additional options in smaller sizes...

Eastman

Well...

From part 4:



"So at design conditions, the BumbleBee will give you the right flow, no

matter what combination of zones is calling.  The BumbleBee will also

vary its speed as it gets warmer out, ultimately spending most of the

heating season running at or near its minimum speed..."



It doesn't work miracles, does he ever mention that the btu delivery will be unbalanced in these examples?  I'd like him to address how different control strategies effect the performance of such incorrectly configured zone systems.



Regarding part 5:

Pretty sure condition "C" is not mathematically possible in relation to "A" and "B".

hot_rod

sounds like

you are angling for a PR job at Taco, Chris



One of the first ads for the BumbleeBee read



"So called variable speed ECM pumps imported from Europe are not as smart as they look. They are designed for European systems which operate on constant circulation with non electric valves"



And ends with



"The bottom line is that they don't save much energy"



I have 6 different ECM pumps on my various hydronic, wood, and solar system here, including the Alpha, Bumblebee and Xylem ECO versions.



I put a KilloWatt meter on the previous pump, and on the replacement ECM. In every case, regardless of the fixed speed solar DB application, or the autoadapt function the electricial consumption was cut by 50- 60%.



I'll end up with 10 circs between my home, shop, and mother in laws place, counting 4 solar systems and 3 hydronic systems.



To me a 50% cut in power consumption is a big energy savings? With over 5 million Grundfos Alphas in service, that savings should not be dismissed.

SpeyFitter

Marketing bafflegab

Sorry but this is just another case of marketing bafflegab. No one ever sold pumps by claiming to have a second best product. Also the Europeans are about as electrically conscious as anyone in the circulatory department and delta p is a strong reason for that.

CMadatMe

Not At All

Nope like my job and not going anywhere. I just find it fascinating that when a new idea or product comes along everyone takes it as offensive because they feel that they are being called out or that what they have been doing for a number of years is wrong.



I think this blog is showing the truth in the operation of both pumps based on the conditions given. What's unfair about that? I don't see any bashing of product nor do I not see any untruths.



Everyone is open to post their own blog or thoughts on this. But so far all I have seen is opinions and not comparison or facts as to the operation of pumps. I don't think John mentioned anything about electrical in any of the blogs but electrical is a big part in the energy savings when you have a wall of old fixed speed pumps.



His focus has been on flow delivery which means btu/hr and how each pumps reaction effects the system.



I think everyone needs to take a step back and take the information for what its worth. Information and pick the pump that fits your job. I don't think anyone is saying use one pump over another. It's saying, this is how it reacts and what happens under these conditions.



He's given the map so plot it on your next job and see which one fits best and use it..

CMadatMe

Whether Delta-P or T

Neither has any reason electrical savings its the motor. I can still vary the speed of a pump with a standard motor so saying Delta-P is the reasoning makes no sense. ECM motors are also mandated by the government. That's like saying all the boiler mfgs decided on a morale standard to go to some type of outdoor compensation controls on the boilers here last Sept.

hot_rod

"Everybody takes it as offensive"

??? A handful like to question authority is what I see. That's how we all learn and evolve. That's a good thing. Simmer down now, Chris;)

SWEI

Electrical savings

Come from two factors:  The improved electrical efficiency of a permanent magnet synchronous motor (typically 92-96%) over a fractional horsepower single phase induction motor (typically 50-60%) is quite significant.  Once you add in the savings from variable speed operation (whatever the control algorithm) the result is a huge drop in annual energy usage.

Rich_49

How it got started

http://www.linkedin.com/groups/Delta-T-vs-Delta-P-3753681.S.226828119?qid=cdaadf1d-8fcf-41b5-b89a-0da809e9d4b8&trk=group_most_popular-0-b-ttl&goback=%2Egmp_3753681

Above is a link to a discussion that took place recently on LinkedIn . It was being watched by some at Taco .  This is what initiated the Delta P / Delta T blog series so as to clarify the differences between the 2 technologies .

My position is that Delta T is superior to Delta T simply because if our we want to control DeltaT ,  both will save money on the electrical end but what product has a more favorable effect on our emitters . 



The article that was written by Mr. Brandon is in Mechanical Business March April Edition , Page 52 .

http://www.mechanicalbusiness.com/digital-issues/

SWEI

My Position

Is that there are applications for both ∆P and ∆T (and I'd prefer to have both options selectable using one SKU.)



Edit: Just read most of the LInkedIn discussion, whew!

Quote from one of Rodney's last posts:



Basically, for the example given, the system requirements are way, way, way below the pump capability.



This is precisely what I was alluding to above.  The correct answer is to get a smaller pump, but neither Taco, Wilo, Grundfos, nor B&G currently offer smaller ECM circs (the ecocirc e3 is not available with ∆P or ∆T control.)  Running any pump at the edge of its operating envelope is asking for trouble.



If Taco offered the 'Bee in 2-3 smaller sizes, we could build mini LoadMatch systems and eliminate zone valves altogether.  I'm ready...

SpeyFitter

Smaller Circulators

Speaking of smaller circs I seem to recall hearing somewhere that Wilo actually had some individual circulators that mounted on a radiant manifold and fed each loop individually. Anyone see anything like this?

SWEI

Wilo Geniax

http://www.tealinternational.com/ThinkHydronics/Articles/ISHsummary/ISH2011.htm is quite tantalizing.

NRT_Rob

the marketing BS in this

reeks.



You absolutely cannot make a pump run faster in constant pressure mode by closing zones. That's a ridiculous statement. It will run as fast as it needs to in order to create a certain amount of pressure. opening up additional zones makes that a REQUIREMENT that it run faster to maintain the same pressure.



that's like saying you can fill up a bucket by drilling a hole in it.



Taco is losing a LOT of respect from me with their really, really bad arguments for the bumblebee. trying to claim you can make a boiler cycle less by slowing down flow... also a very poor argument.

Eastman

The examples he picked

are very odd.  I don't understand why he is not emphasizing conditions where a more persuasive argument could be made for delta T. 



Also, this blog series is focused on the manifold side of the heating system, but I don't think it's possible to completely analyze the impact of a pumping strategy without considering the primary side.  For example, I don't see the benefit in locking the secondary delta only to  leave the primary loop to modulate on fixed flow.  Seems like there should be a better solution for this particular case.

hot_rod

offering

the ability to use the ∆T in either mode will open up more possibilities. I'm not sure how a focus group missed that unique option. Rumor is that may be available on the next version?



When I heard this circ was hitting the market I doodled out a few different applications with "reverse ∆T" I think this is where the biggest bang for the Bee will be, selectable ∆T.



The version I have is a bit noisy on full speed. A whirling blender noise of sorts? Other brands of wet rotor ECM circs are completely silent.



"Put me through some changes, Lord. Sort of like a Waring blender" Warren Zevon

knotgrumpy

More like

Lawyers, guns and money...

Eastman

I feel the implicit conclusion of this article

is that your average residential system should be using 3/8 or less tubing.

R Mannino

The Bigger Problem

is the boiler that can meet the demand of 3/8" pipe.

Can we make one small enough?

SWEI

offering begs the question

How long 'till JB cites Zevon?



I agree -- more modes, more better on ECM circs.  More sizes, more better too!

Rich_49

Zevon was last year SWEI

http://jbblog.flopro.taco-hvac.com/lawyers-guns-money/

Rich_49

and in 2010

Go figure

http://jbblog.flopro.taco-hvac.com/werewolves-and-boilers-of-london/

Rich_49

Why

3/8" tubing ?   You like high head pressures and more manifold outlets ?

Eastman

the dT vs dP debate seemed to quickly

reveal itself as an argument over which strategy insures the pump gets to and remains at its minimum speed first.  If so little energy is really necessary for pumping in a typical manifold system, perhaps one is better off taking advantage of this efficiency and downsizing diameters or significantly increasing loop lengths when the opportunity arises.

CMadatMe

I Feel That

A lot of people have taken it all out of context. I take JB's blog as education in looking at both pumps and seeing which one fits the application I'm looking at. They both have their place and there is nothing wrong with plotting how each pump would react in a particular job and pick the one that fits best.



Reality is that for the application he is putting both pumps in that is how each pump reacts under those conditions per how the pumps are set up. If everyone remembers the first paragraph in the first blog he says, take it how you see fit.

Eastman

Likewise

When the electrical power usage difference between these pumping strategies is probably only around 10 watts or less, isn't the thermodynamic performance impact a critical variable?  Keep in mind that 10 watts is about 34 btu/hour.  And minimum heat source btu output is often 10,000 btus and up.  I feel like I'm not seeing a complete picture in this debate regarding total system efficiency.

Rich_49

You will

inevitably end up with at least a few loops or manifolds including S&R that will exceed the head pressures any of these pumps can deliver . Than what , use a 008VDT and save no electricity ?  

I must say it is very cool to Know for sure that your radiant panel is operating at it's designed for Delta T . Never could nail that 100% of the time no matter the conditions  with Delta P circs , do it regularly with Delta T  . Just sayin !

Eastman

I don't understand the

desire to hit design temp delta 100% of the time.  If a system requires a 20 degree delta at 160 supply temperature, does it also require a 20 degree delta on day that is calling for 120 degree supply?

Rich_49

Watts are watts

and BTUs are BTUs . Unless we are using an electric boiler the pump wattage and BTUs have not much to do with each other .  A 007 uses X amount of watts and can deliver a wide range of BTUs to the system , it will work on a 170,000 boiler @ 4' of head , and a 75,000 boiler at 8' of head and if those are your requirements it will maintain the designed for Delta T at design conditions at one wattage , but what about the rest of the time when your system really only need be 130,000 or 45,000 , will your Delta T not narrow ? The Delta t pump will have you pretty damn near system requirements ALOT of the time .  Let's not get increased electrical efficiency causing guys to make design choices they normally would not . That kinda goes against why this technology was created .  

Rich_49

Yes

Eastman , it does .  Certain heat emitters work optimally at a certain Delta .  Why would one let Delta run wild and go wherever it wants ? Bad Parents .  at 160 or 120 the manufacturer of that emitter wants the same Delta T .  

Eastman

My point was that electrical efficiency

probably doesn't correlate directly with total system efficiency or total operating costs.  I was hoping to illustrate that by comparing the minute power differential between dT and dP pumps relative to the massive amount of thermal energy that is typically being transported.  For example, the pumping power is typically less than 1% of what is being burned, even at the minimum modulation of the smallest modcons.

Eastman

What kind of emitters

did you have in mind?  Does a radiator need a fixed delta?

hot_rod

todays modern hydronic systems

like to embrace varing temperatures, which is why we see so many mod-con boilers and not just -con boilers. They strive to match the supply temperature to the load. Also low supply temperatures are a good target to shot for, all boilers are most efficient at low operating temperatures, even non condensing boilers as long as return temperature protection is provided.. Condensing boilers like cold return temperatures, and if they are run on ODR then the temperature (mod-con) always changes to the load.



∆T wants, and likes to vary as supply temperature is reduced.



I'm not sure what heat emitters demand, or run optimally at a fixed ∆T and, or why? Can you point us to a manufacturer that dictates a certain, fixed ∆T for their product?



The Uponor design manuals for radiant show both 10 and 20 ∆T choice. A tighter ∆T could be selected for more even floor temperature and comfort on a bare slab for example. in a large commercial slab, you could run a wider, maybe even a 30 ∆T. in both cases the ∆T could change as supply ramps down on lower load conditions.



If a piece of baseboard has a 180F supply and 160F return, the output is based on the 170F average across the board. Look at the manufacturers output chart and see how many BTU/ ft it will transfer at 170F.



If you chose to run a wide ∆T, maybe for pump sizing or pipe sizing reasons, or you embrace the Euro approach 180F return at 140F the average is 160F. Look at the output charts to see what that equates to.



Panel rads are a good match for wide ∆T as they don't depend on just convection transfer like a fin tube emitter. If you follow any of the Jaga teachings they propose below 120F supply, some of their forced convection emitters can run at 90F supply. I don't think a forced 20 ∆T would be wise for that, why not let the ∆T adjust to cover the load? If the system controls allow the supply to run down to 90F, let the ∆T run 10- 12, if it ramps to 140F supply, why not let it run a wider ∆T?

Eastman

I would expect the optimal system

delta to fall as heating demand decreases and lower supply temperatures are called for.  I would expect a low temperature system in particular to develop unbalanced btu delivery within a zone over the course of the season if a fixed delta was enforced on the circuit.



--Don't get me wrong though, I'm not advocating for delta P, but surely there is a better control strategy than either one.

SWEI

or just size the pump properly

sorry to sound like a broken record, but 008 hydraulics are not the solution to all problems -- even when you run them on a VFD.



Missed the Zevon posts - thanks.  Still have my original Excitable Boy LP on the shelf.  Miss that guy.

Rich_49

Uponor

offers a choice of Delta T based on product used and installation method . They would like to see 10* for floors unless you are using quiktrak which requires a 20* Delta T , embedded , LW overpour and joist trak are supported at 10* . Warmboard wants 10* , Thermal Trak wants 20* .   Am I mistaken or do we design systems using a designed for Delta T ?  We no longer have to accept swings in system Delta because we have tools that allow us to more tightly control how our systems operate .  We are already changing the SWT to compensate for differing conditions , why make our equipment work at different levels of efficiency . Sure , we could make the Delta T whatever we want and the exchange of BTU from the emitter to the space will change every time we do that .   

   Same system different pumps , Ready ?

1 zone calling , 10,000 requirement , 20* Delta T , doesn't matter what temp .  1 GPM .   Delta T pump .

Same as above @ 12* Delta T  ,  1.66 GPM .

  We can do anything we want like I said but isn't what we are doing primarily about occupant comfort , energy efficiency ? If an emitter performs optimally at a tested flow and we know that flow or Delta will maximize our source efficiency why would we accept less ? 

And then there's the electricity used .

Although this paper was written about building practices it applies to us , please read it ,

http://www.buildingscience.com/documents/insights/bsi-007-prioritizing-green-it-s-the-energy-stupid

 

hot_rod

so if a system

has a mix of slab with floor coverings, and quick trak or Warmboard operating at the exact same design temperature, do you set for a 10 or 20 ∆T?



The beauty of a design software is it allows you to adjust tube spacing, loop length, or flow rates to match temperature requirements. This eliminates having multiple mixing devices, reduces cost and complexity. Also the entire system can operate on one ODR device.



I believe the RPA suggested if temperature requirements for different zones of installations were within 10 degrees of one another, additional mixing devices were not needed.



I'm still not sure where the word "wants" comes into selecting design ∆T? The Wirsbo design manual I have, a bit dated, Appendix F, gives you a choice of 10 or 20 ∆T for each and every installation method. I suspect that would include a 11, 12, 13, 14, 15, etc ∆T designs.



I have installed quite a few commercial slabs, with manufacturer designs, that were built around 30 ∆T. This allows for long loop lengths which are also helpful in big open buildings.



Properly designed and installed systems run efficiently, and comfortably with an un-fixed ∆T, that's what they "want"



If you start a concrete slab radiant on a cold winter day, slab at 35F, why would you limit that to a fixed ∆T. If the heat input "device" condensing boiler, heat pump, solar, etc, can handle it why not a 40 or 50 ∆T on start up, and taper down as the slab approaches max. operating temperature? In fact any of those heat input devices increase efficiency as the retuir temperature is lowered, more condensing in a condensing boiler, closer approach temperatures for the HOP, less ambient losses for the solar collectors.



This is why I try shifting the conversation to electrical energy efficiency. If the circ, regardless of ∆T or ∆P logic, can save 40- 60% operating cost, while still providing comfort and reliability, that is worth talking about with a customer. Especially if their plan has 10- 20 circs included.



The ∆T pump spiel, to me, feels like they are selling the sizzle, not the steak. Suppose sometime in the future they were to offer a small ∆P circ, how would that be promoted?



Is the Viridian ∆P circ just for large "Euro" system? Zoned with TRVs?

CMadatMe

I See Alot Of Big % Numbers

But % of what? $100.00 operating cost, $1,000 operating cost. Let's define a dollar amount. It's nice to see big percentage numbers but what are we talking about in dollars and cents? Are we replacing pump for pump or removing pumps and adding zone valves to lower our electrical footprint.



The electrical talk while valid also needs to be looked at on a job by job basis.

hot_rod

big picture thinking

It's not just the savings for one residential customer with a few circs running. I'm thinking about all circs that you and hundreds of dealers, installers, and manufacturers sell to consumers.



It's like you are saying I don't recycle my trash because my six beer cans ( a week, day, or per hour) don't make a difference :0



Polls show (NAHB data) that consumers have energy efficiency at the top of the list when building new or up grading appliances and HVAC components.





Notice car ads on TV tout MPG more then ever before, that is a big part of what consumers base their decision on. To the extreme point that one manufacturer has been padding their MPG numbers to sway buyers.





Marketing a "green" green pump to homeowners would probably sell many mores circs more then trying to explain ∆T or ∆P via a contractor. Isn't this what the multi million dollar Canadian Beautiful Heat campaign is all about?



Consumers understand their electricity cost more so then pumping logic.



Isn't the goal here to sell better, more efficient "stuff" that the consumer "wants" and is asking for?

Eastman

I think you're confusing

the function of suggested max deltas.  10 and 20 are conveniently nice numbers, doesn't it seem odd that optimal performance happens to fall on multiples of 10?



"Am I mistaken or do we design systems using a designed for Delta T ?"



The delta in question is in reference to peak output on design day.  To extrapolate this value and apply it to other design conditions and ODR temperatures seems unfounded to me.  It is this relationship that I am questioning.  Fixed delta seems like a holdover from less sophisticated fixed temperature and fixed flow.  If one has the ability now to control delta T,  how should it be varied in relation to other system parameters?  Perhaps there is a relationship that is better.

Eastman

Cost

There are 720 hours in a month.  10 watts is 0.01 kilowatts. 



720 hours/month x 0.01 kilowatts = 7.2 kilowatt hours



What's the typical cost electricity?  Call it 12 cents?



7.2 x 12 cents = 87 cents per month.  Is the math good?



I think the power usage difference between deltaP and T is typically around 10 watts or less.   And a bit more if we're comparing to fixed speed ECM circ.



So, if you buy my assumptions we are probably arguing over around a dollar or less in electricity per month per pump.  Certainly in a one or two pump manifold system thermodynamic performance and occupant comfort should likely dominate debate.