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Delta-P/Delta-T Part #5 (63 Posts)
Delta-P/Delta-T Part #5It's getting more interesting. Come on guys haven't heard back from you in a while. Sure sounds fair and accurate.
http://jbblog.flopro.taco-hvac.com/trouble-boys-2/"The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
I'm just curioushow 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...
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".
sounds likeyou 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.
Not At AllNope 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.."The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."This post was edited by an admin on May 29, 2013 9:51 AM.
Marketing bafflegabSorry 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.Class 'A' Gas Fitter - Certified Hydronic Systems Designer - Journeyman Plumber
Whether Delta-P or TNeither 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."The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
Electrical savingsCome 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.
"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;)
How it got startedhttp://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/You didn't get what you didn't pay for and it will never be what you thought it would
My PositionIs 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...This post was edited by an admin on June 2, 2013 1:58 AM.
Smaller CirculatorsSpeaking 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?Class 'A' Gas Fitter - Certified Hydronic Systems Designer - Journeyman Plumber
Wilo Geniaxhttp://www.tealinternational.com/ThinkHydronics/Articles/ISHsummary/ISH2011.htm is quite tantalizing.
the marketing BS in thisreeks.
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.NRT.Rob
The examples he pickedare 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.This post was edited by an admin on June 3, 2013 10:29 PM.
offeringthe 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
More likeLawyers, guns and money...
offering begs the questionHow long 'till JB cites Zevon?
I agree -- more modes, more better on ECM circs. More sizes, more better too!
I feel the implicit conclusion of this articleis that your average residential system should be using 3/8 or less tubing.
The Bigger Problemis the boiler that can meet the demand of 3/8" pipe.
Can we make one small enough?
Zevon was last year SWEIhttp://jbblog.flopro.taco-hvac.com/lawyers-guns-money/You didn't get what you didn't pay for and it will never be what you thought it would
and in 2010Go figure
http://jbblog.flopro.taco-hvac.com/werewolves-and-boilers-of-london/You didn't get what you didn't pay for and it will never be what you thought it would
Why3/8" tubing ? You like high head pressures and more manifold outlets ?You didn't get what you didn't pay for and it will never be what you thought it would
the dT vs dP debate seemed to quicklyreveal 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.
or just size the pump properlysorry 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.This post was edited by an admin on June 6, 2013 2:34 AM.
LikewiseWhen 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.
I Feel ThatA 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.
You willinevitably 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 !You didn't get what you didn't pay for and it will never be what you thought it would
I don't understand thedesire 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?
Watts are wattsand 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 .You didn't get what you didn't pay for and it will never be what you thought it would
My point was that electrical efficiencyprobably 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.This post was edited by an admin on June 5, 2013 10:09 PM.
YesEastman , 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 .You didn't get what you didn't pay for and it will never be what you thought it would
What kind of emittersdid you have in mind? Does a radiator need a fixed delta?
todays modern hydronic systemslike 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?
I would expect the optimal systemdelta 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.This post was edited by an admin on June 5, 2013 10:54 PM.
Uponoroffers 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 ,
You didn't get what you didn't pay for and it will never be what you thought it would
I think you're confusingthe 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.
so if a systemhas 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?
Bob ( 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 would do as I always do in this instance . Use a single temp , zone it appropriately ( actuators) , 2 remote manifolds , 2 circs , 1 for each Delta .
" Wants " comes into selecting Design Delta from the following philosophy :
Smith's Environmental Low temp convectors open on 110* , close on 130* .
Buderus Panel radiator 18*F or 36*F Delta T
Warm board recommends 10 Delta T to insure rated output
Uponor recommends 10* Delta for floors except Quiktrak which is to be 20* Delta T .Uponor CDAM " Flow rates for ALL Quiktrak installations are calculated to a 20*F temperature differential " Appendix F is only Generic flow charts for 10 & 20 * Delta T with (100% water) or without differing %'s of Glycol
If you start a concrete slab at 35* .
If you have a concrete slab that is 35* that has been operating call an attorney . But in the instance that it did happen on a 10,000 sq ft slab in Eau Claire ,Wi on a -13*F day this is what would be required . 178,789 BTU , 53 loops , room design temp 55*F .
10*T SWT = 77 , 87* from boiler , returning 67* , 35.8 GPM @ 5.4 '
50*T SWT = 97 . 122*F from boiler , returning 72* , 7.2 GPM @ .33'
Now how long do you think it will take that slab to get up to temp ? Probably just in time for everyone to punch the clock , turn the heat off in the warehouse , and hope the whole place does not freeze up overnight . Let's try to heep things realistic for the sake of progress . I would point out that the 10* Delta system's boiler will enjoy an albeit ever so slight higher efficiency . Maybe someone will create the pump that will allow multiple , modulating Deltas in the future .
Care to substantiate claims about compensated folks ? No Bob not particularly . You Know better than that . But feel free to do the research I have done on those who start threads about all sorts of stuff .
You didn't get what you didn't pay for and it will never be what you thought it would
I See Alot Of Big % NumbersBut % 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.
big picture thinkingIt'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?
CostThere 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.
80W vs 10Wor 80 vs 40W maybe more average. This is where I was going. If you install or replace a circ, up-selling to an ECM just for the energy savings, even running on a fixed speed mode component may appeal to buyers.
Keeping in mind consumers spend 10- 20 K for SDHW systems to to offset 300 bucks a year worth of energy savings. Same with multi thousand dollar PV systems, when a KW is 7 cents in my area, 4 cents for off peak in some states.
I doubt many consumers know or care about the ∆ twins, or could follow the discussion if you were to engage them :) Even the pros here have spinning heads watching this T vs P discussion. Offer your customer nicer, more efficient equipment, they often say yes!
I doubt phones will be ringing off the hook with customers gushing about how much more comfortable their building is with a few degrees different control of the ∆T. But they will brag about efficient light bulbs, appliances, cars, etc.
RightThe marketing war is for the contractor not the consumer. The flow pro blog isn't being read by the average homeowner, it's intended for people that are already considering ECM or would like to utilize the delta function. I'm sure Taco would be more than happy if the end user even associated them with hydronic systems.
I don't think the goal should be up selling at all cost, but clearly ECM has a place in this industry. How does one decide which version to pick for a given situation, though? I don't feel like there is framework of thought out there that is totally convincing.
Eastmanwill the pressure in the system change with differing flows at differing temperatures ? I think so and this is my case for Delta T over Delta P . One can do what the other can and one cannot perform the added function . I will spend my customers money on the higher level of control and options . By the way , I don't know if anyone has noticed but most of the Delta T bashing has been originating from those paid by competitors as far as I can tell through researching the names associated with starting the discussions . Remember that Taco produces both technologies .You didn't get what you didn't pay for and it will never be what you thought it would
questioning fuzzy logic is bashing?I thought the intent of "The Wall" was to question, learn and share experiences. Share what we have all learned from the years of collective knowledge. That's why I signed up.
Care to substantiate that claim about paid competitors asking the tough questions?
Why would anyone keep starting a fresh thread about this topic unless they wanted to hear more opinions?
Can't take the heat, stay out of the boiler room, or let the ∆T be free :)
Wow!That is quite a claim. I've asked questions about this topic. Am I a spy from Grundfos? Wilo? Xylem? Nah. Just a guy who likes to tinker with and think about mechanical things.
Besides - if the 'competition' is going to rush to produce Delta T circs soon anyway, why would their moles question the technology?
Address payments to...How do I sign up?
Rich, I hope I don't sound like I'm trying to promote delta P. I think there are uses for delta T, delta P, and fixed speed ECM. (And all the hybrid modes that are available on some units.)
BashingMy entire point has been that John has not been bashing. He's been showing how both pumps operate under the conditions in his blog. It's information and education for contractors that haven't a clue as to how either pump operates.
Take the knowledge apply both pumps operation to your job and pick the one that fits best for you. What's wrong with that. He hasn't said anything that is not 100 percent true.This post was edited by an admin on June 6, 2013 10:03 PM.
I havea lot of respect for john... he was the first trainer I ever experienced in this industry. he's a great guy.
but the fact is you cannot make a pump speed up by closing zones. can. not. happen. ever, in any circumstances, no matter what.
so he is NOT educating and he is NOT being even handed in this matter. he's wrong. and he's using sales BS... either intentionally, or mistakenly. but either way, this is a fluff piece, not serious analysis.
Delta T has a place. Delta P has a place. but Delta T doesn't get its place by being misleading about how Delta P operates.NRT.Rob
How Can You SayYou cannot change pressure by opening and closing zone valves? Are you saying each zone has the exact same head loss and flow requirement? So no matter what, I'm moving x gpm consistently no matter the zone length, head loss or btu/hr requirement 24hrs a day seven days week or as long as the pump is running?
nicestraw man there. I didn't say you couldn't change pressure.
I said: you cannot SPEED UP a pump by CLOSING zone valves. not in a real, operating system. but his analysis says, in fact, you can.NRT.Rob
Conditions A, B, and Cimplicitly define two different head requirements at the same flow for some of the zones. Hence the erroneous conclusion.
You cannotSpeed up a pump by closing zone valves ! Rob , you may possibly want to read the blog you are referencing . I believe John said as zone valves close the circ will slow down .You didn't get what you didn't pay for and it will never be what you thought it would
Read it again.John is saying that 2 small zones running could run faster than all 3 zones calling. in his blog, condition "b" vs condition "c".
that is not possible in a real system with the equipment he is talking about.NRT.Rob
Show UsWhat happens Rob so we can all see. Your throwing opinion and not seeing any facts. Chart it, plot it and write it. Show us what happens. We are all here to learn more. I need more information then just opinion. I'm a, have to visually see guy.
From the articleEdit failure. Somehow everything got erased.
From the article
"But it’s when the two smaller zones are calling that this gets
interesting. If you calculate out the system curve of 4 GPM at 2′ of
head (Red B), plot the points and connect the dots, you see where that
system curve intersects the pump curve (Purple B). Not only is actual
flow rate more than 2.5 times what it needs to be (10.5 GPM vs. 4 GPM),
the pump will be running close to full speed.
In fact, it’ll run faster with two zones calling than it will with all three zones calling.
Program the Delta-P pump more accurately, the situation improves, but the same dynamic exists:
see attached image
The circulator is dead on with all three zones calling, but when the
small zones are calling, the supplied flow rate will be double what it
required, and the circulator will still go faster with two zones calling
than it does with three zones calling."
I think this is a good example of why balancing is important. Adding hydraulic resistance to zones 1 and 2 actually improves efficiency while leaving additional pumping capacity for future zones.
For reference: Condition A is zone 1 calling, B is zones 1 and 2 calling, C is 1, 2, and 3 calling together. Zones 1 and 2 required 2gpm at about 1' of head. Zone 3 required 3 gpm at 4'. The problem here is that John added the target flows from zones 1 and 2 at 1' of head to the target flow of zone 3 at 4' of head, and then called that condition C. (the red one) This is not a physically possible condition though, as at 4' of head, zones 1 and 2 will be moving much more water then required.This post was edited by an admin on June 7, 2013 4:32 PM.
Bob (Hot Rod)First question ;
1 SWT , 2 manifolds , ? zones ( actuators) , 2 Delta Ts .
35* slab .
If this were to happen I would recommend contacting an attorney .
10,000 sq ft slab , Eau Claire , Wi , -13*F ODT , 55*F IDT, 4 large garage doors on 1 wall , 12" spacing , 1/2 pex , 53 loops , 178,789 BTU .
10* Delta T 77* SWT = 87* from boiler , 67 returning . 35.8 GPM @ 5.4 feet .
30* Delta T 87* SWT= 102* from boiler , 72* returning . 11.9 GPM @ .81 feet .
Will the 30* slab even heat up before it is time to punch the clock and go home . You know this slab would never be less than 60* surface temp except at startup , by the way we probably should not let this or any slab suffer such temperature swings . Keep it real Bob for progress's sake .
Substantiate claims . You know better than that . Anyone should feel free to research those who start the debate to find out who feeds their families .You didn't get what you didn't pay for and it will never be what you thought it would
come on RichEveryone of these ∆ posts were started by Chris, I suspect he wants to learn and hear other opinions. I don't feel he is bashing anyone or product?
I'm not attacking you, bashing a product or person. I am, like others questioning some fuzzy math, and how it relates to actual heat transfer.
So, again if you are hurling accusations in a public forum, man up and tell us who you refer to. You owe it to all that are following this post. Feel free to PM me if you'd like to carry on this conversation.
I suspect we will see some non biased opinions and articles on the topic of heat transfer and what actually happens to heat emitter output when you force the flow laminar.
Let the installers make choice which technology best suits their job and customer, once the math and concepts of thermaldynamics is applied together in a non biased way.
Also, no need to call an attorney when you start a snowmelt slab on a 35F day :) Or even a building slab for the very first time on winters day. It happens, the ∆T changes a lot as they warm, and they are just fine.
By the way , I don't know if anyone has noticed but most of the Delta T bashing has been originating from those paid by competitors as far as I can tell through researching the names associated with starting the discussions . Remember that Taco produces both technologies .
Chrisis not who I am referring to . Don't quite know how anyone got that idea but if they did I apologize . I refer to others Bob , from other forums . Please see one of my first posts here titled " How it got started " . Did not think you were talking about a snowmelt slab , accept my apologies but again I have not encountered snow at 35* but then I would start the slab early in forecast of snow .
I too have no problem with laminar flow vs turbulent and if you read that How it got started discussion my viewpoint on things , old standards , agencies that think they know will become quite apparent .
I will PM you to discuss other things further .You didn't get what you didn't pay for and it will never be what you thought it would
PayrollRich, conversion with paid reps is a lot more entertaining and should be the norm on contractor oriented sites. What forums are they on? Get them over here if you can. I think a lot corporations use marketing proxy wars, which is really too bad. Engaging the curious customer directly is always a positive strategy and eliminates the possibility of miscommunication. I'm surprised we don't hear from more people on the take.
Edit: I meant to say ~conversation~, but I guess ~conversion~ could work too.This post was edited by an admin on June 8, 2013 2:59 AM.
I Posted ThemBecause from the 1st one there was a lot of opinion and wanted to make sure the entire process of the blog was seen. There still is one more to finish it out.
I enjoy reading each and every opinion. You never no what you might learn or pick up on. I'll still stick my stance of, use John's blog and what you know about a Delta-P pump and choose the one that works best for you.
There is not a right or wrong nor a good or bad. In any case both styles of pumps will work. One may tend to working better in a particular application over another and that's for you, the installer to choose.
That in my opinion, is what his entire blog is about. Remember the first blog? Information, take it how you choose.
The other Green pumpalso can be made Delta T with the use of IR package .You didn't get what you didn't pay for and it will never be what you thought it would