Discussion in 'Maintenance and Troubleshooting' started by Dakotafig, Oct 14, 2015.
Is it possible to make a transition elbow that goes from 18"x18" to 8"x32"?
Turning vanes are used by guys who understand that an equal air flow through the oversized vertical heat exchanger, which is placed right behind the return shoe, is crucial for the performance of the heatpump.
This is something a drop cheek elbow itself cannot achieve, the majority of the air then always hits the upper part of the coil (as visible by dirtier upper portion of the filter) and leads to higher refrigerant pressure in the lower coil, meaning decreased efficiency.
Well we disagree with that. That is actually insane as you are the furthest away from the truth on that one.
But I will leave that one alone. But I will say check out manual d sometime it is amazing what they teach us.
Yes we can go from 18x18 to 32x8 by allowing enough distance on your throat. We always allow 18" on our throats so that you are not choking down the fitting. But the opening on the geothermal should be much bigger than 18x18.
If not then we would make a centered tapered transition from
Turning vanes are only needed in situations where the contractor made mitered fittings instead of the proper radius throat and back Ells. Just check most manufacturers install methods and they even specify radius fittings and fittings with turning vanes.
Again turning vanes are to repair a faulty designed duct system.
You get absolute coil coverage with the radius throat and back ell as there is no where else for the air to be trapped and swirled with that design.
And yes there is a science behind adequate design and installation of a good duct system.
I hope this helps.
You might not understand that this is not about decreasing air flow resistance, but to ensure that the coil is seeing the same amount of airflow in every area.
Size of the heat exchanger/coil is usually 28x30" so you need to have even flow through all parts of that area.
Why don't you show us where in the manual D, which you always refer to and you seem to know well, it addresses the means which are needed to ensure equal flow through a vertical coil which is positioned right after a 90 degree turn.
I am also sure you have good backup evidence, since you are calling me "insane an further away from the truth".
Keep in mind that this is on the suction side of the blower, where air is moved via negative pressure, not positive pressure, like on the supply side.
All I can say is that we conducted tests with our monitoring systems, and have installed curved return shoes, and square ones.
http://welserver.com/WEL0662/ for curved
http://welserver.com/WEL0713/ for squared
It made no difference in the COP of the units wether they were curved or not. However, the COP dropped significantly if no turning vanes were installed in the return shoe. Essentially only a portion of the coil saw airflow, namely the upper portion (again, the air is sucked in with negative pressure) so the unit behaved as if would have a dirty filter. The refrigerant pressure was higher, resulting in higher electricity use by the compressor.
Climatemaster does recommend vanes in the return and supply. The pictures show curved elbow transitions but don't list those as requirements. I obviously have an issue, potentially on both sides. I don't know if the contractor I hired knows how to make curved elbows or not but he acted like he didn't. Doing that should most likely fix the turbulence in the supply duct. I never thought about the COP being impacted by something on the return side.
If vanes were put in there I'm not for sure where I will put my power humidifier as there really isn't room in the supply duct.
Lastly, the supply flange on the unit itself is 18" x 18" and that is the size of the pieces that were sent to screw the plenum to. If it is supposed to be bigger than that, how would that be accomplished?
Just like all the skilled trades, no one wants to pay the apprenticeship price to bang tin.
O.K the supply opening on the CM should be close to 13x13 depending on if you used an external heater package. You would then do a transition from that to your 32 side and then make a 32x8 short way wye. That solves the supply side in the design of airflow. But you then would have to big of a supply duct for each direction as you shouldnt need 32x8 duct to go each way. A 4 ton system cant push that much air. So you would need a damper on each side so that you can actually shut down each side to balance it out.
Once you do this you can then address the return side.
Please trust me as this is the most neglected side of all HVAC systems because of the sizing and space required to install it correctly.
I have armed you with enough info to do the math yourself to understand that your duct system return is undersized along with a very restrictive design. I have been in business since 2001 and can count on both hands how many compressors I have had fail. Thats for a reason.
The return side is just as important if not more than the supply side. But usually most contractors either don't have the equipment or knowledge to do the sheetmetal job right the first time.
If you had the time and equipment to log static pressure reading with a good digital meter at certain locations. You then find someone to make the fittings and install them. I will promise you that the noise will disappear and your new testing will show you the proof that I speak of.
4 ton system needs 1600 cfm design and you have 1000 on the return side
If you cant find someone to make your fittings as I doubt you will please let me know.
I can personally hook you up.
Any professional sheet metal company never uses turning vanes as again it is a tall tale sign of a low end contractor.
That kind of work has gotten people fired from our company.
Properly designed fittings get absolutely 100% air coverage at a less EQ feet of restriction versus anything other design. Just check out a little of manual D
Attend any CM factory training and it is in the training materials.
what were the design specs of your ells if you dont mind telling me. And yes actually I do understand them. I would also like to see your tests and results with both systems. Again I would also need you fitting design specs as well
Thanks so much
So I looked at your first job that has the mitered ell with turning vanes. Then I look at the other photo that you claim changes the COP. It isn't even apples to apples.
Your mitered ell set up has a tight 8 inch throat that taps right into your return main duct. This is also a square tapped fitting instead of a return ell fitting. So those connections show that you kind of get it but then you don't.
So you then claim that the second unit is your radius throat and back fitting and that it claims it doesn't cover the entire coil surface area and that it changes the COP.
Well I agree with you because that job has a mitered throat with a radius back which throws the air down right to the bottom of the ell before entering the coil. So that fix is so simple as when you actually take your dividers and swing a radius throat you take the EQ restriction values from 90+ feet of restriction to under 20' if that make sense. Plus on the second system you also have a twist transition which if it isn't done with in 3-4 times in length of fitting it again is a very restrictive fitting.
I again would love the specs of all fittings please sir.
Duct sizing, fitting specs, Unit sizing, All return duct sizing as well of supply duct sizing.
Also wouldn't it be fair if you run a test to disprove a method that you test both on the same system and design to be true and honest?
So no wonder your COP numbers dropped versus turning vanes.
As you didnt do a true radius design nor are these two jobs alike. The second one is much more restrictive than the first one because you dont have turning vanes.
That's the reason your numbers support your theory.
Now do me one favor and remove the fitting with the turning vanes in it and install my ell. I will even be glad to make it and ship it to you. Then let me know what your numbers prove.
Then lets do one more thing lets modify your existing second photo to the proper fittings and then test that system and it will concur what I have stated.
It's ok though because I love teaching others and actually enjoy it.
Turning vanes are effective but as my original statement it is much easier to design and make the fittings than to have a to design a fix for a faulty designed duct system from the get go.
Is that what our customers deserve?
So on your second photo your twist looks to be 25 inches wide and twisting to 26 or 28 by duct. So in that fitting you need to take the widest portion of the duct which lets say 26 x 3 times for the actual length of the twist of 78" long to equal the minimum design of that fitting. Yours looks like it is 24-30" long. So you have a 1 to 1 twist which is extremely restrictive as it needs to have a minimum 3 to 1 and ideal for a 4 to 1.
So yes sir I do understand quite a bit about sheetmetal design and installation
It's called Manual D
I am not trying to single you out but I am just being honest here. As again these are only the average installations in the industry. And in our market place really isn't considered that. Again I am not trying to offend you but your photos speak 1000 words and in my case even more.
plus one is a 7 series vs 5 series
There are no duct fittings called shoes. They have specific names.
Again please read and educate with manual D
Ok, here is a status update at the moment. I convinced the guy to come out and redo some stuff. Just to clarify, the supply flange size on my unit is 18" x 18". He is going to put a smooth radius elbow transition on the supply side that goes from 18" x 18" to the 32" x 8" duct. I think that should take care of the turbulence on the supply side by removing the current "splat" duct transition.
Here is my question on the return side that still isn't making any sense to me. With the area of the return drop I calculate 685 cfm (not counting the basement return). My basement is just one big open area which is the reason for the common basement return grill. 685 cfm is a very respectable velocity for a return, or at least I think so. Also, the real velocity should be less than that because I calculated all 1600 cfm going through the return plenum, obviously the basement return will count for some of the airflow which will drop the velocity even more.
When I am talking about pressure differentials, I am talking about a true differential between the supply side and the return side. At full airflow right now I see about 0.1" of H2O which is far below 0.5" of water column limits. Also, if I take the return completely off, meaning it should be able to get all the air it needs through the brand new filter and the micro channel exchanger and then measure just the supply static pressure I still see about 0.07" of H2O. So, what that is telling me is the return side is putting a restriction of about 0.03" on the system, which is minuscule. Again everything is far below 0.5" of H2O.
I gave the 2 weblinks to show that we had installed curved and squared return boots, I did not say that one system was directly compared to the other.
Obviously that would introduce factors that would not allow a direct comparison, different units, different houses different ductwork etc.
We actually installed different return boots on the same unit and measured before and after, since we noticed different KW draw from the compressor between different installs, and the difference were different return boots installed. Then we found that the difference was not wether a boot was curved or squared, but wether it had turning vanes in there or not. We also noticed that the return boots without turning vanes had filters getting dirty quicker in the upper part of the filter, suggesting that more air is moved through the upper portion of the coil, and lesser through the lower one, resulting in higher refrigerant pressure and more KW draw. After we put in turning vanes to direct more air towards the lower part of the coil, which you call "...a tall tale sign of a low end contractor", the refrigerant pressure dropped, and the COP improved between 8% in 1st stage and 10% in second stage.
So the air does not "get thrown down to the bottom of the ell before entering the coil" as you state, it is actually sucked into the coil by negative pressure, which is the difference between positive pressure in the supply ducts. That also means it goes the shortest way which explains why the majority hits the upper portion of the coil, and not the bottom of the boot, as you state.
So it does not matter by what return boot design you achieve that the same amount of air floats through each portion of the coil.
While you think that turning vanes are nothing but a fix for a faulty design, and that our customers deserve better, we are streaming data from many of our systems live here, with the delta T on the air side, and the compressor and fan power, including the overall efficiency. Our customers want (and deserve) efficient systems at at the lowest possible costs, without sacrificing performance. The monitoring data we stream public demonstrates that.
Why don't you show anybody here that you can do the same, and actually contribute here with data and evidence, instead you are making a lot of claims without any supportive data.
supportive data. It's called manual D. And your so called curved boot does not have a radius throat, it is a mitered throat. If you actually understood duct design there wouldn't even be an argument. Please spend time and actually understand manual D.
Your the one that needs to prove your false claims not me.
If need be i will take a picture out of the manual D book to educate you on proper duct fittings, name, and most importantly design.
Look I am just calling it as we see it.
Sorry that your not as great as you claim.
The bad thing is all you need to do is swing your dividers on the inside throat and you got it but you would rather argue that your right even though your design is a 6 out of 10. And yes your customers do deserve better because a very restrictive duct system cuts down on efficiency and COP. And unit repairs.
We haven't even looked at your supply side yet.
Please provide me with more photos, true static pressures and your actual test result that you claim as well as the photos of the entire ducted tie in.
And you did supply both examples to prove me wrong about COP when you do not have a true radius fitting and there is a big difference in EQL of a mitered throat. But it does prove what I have been saying. Your turning vanes are performing better than your so called radius shoe because your radius ell has a radius back but a mitered throat which the EQL is 90' of restriction. Swing the throat to radius and open your eyes to being the best contractor in your area and then run your testing. And if I am wrong then I will eat all my crow I promise.
So stop trying to pull the wool over everyone's eyes that your so great when all I see is sub par work at the best.
When people start to offer actual methods that we are all supposed to be designing to you are very offensive because you obviously dont design to those standards.
I don't care about data logging if you cant prove your actual recordings of both return ells. Plus you don't even have a true radius ell. you only made a radius back ell with a mitered throat.
Please go to the following link to view the proper fitting that has an actual name other than a shoe. It is called either a " short way transitioning ell", or drop cheek ell. Depending on your terminology. Once on that website go to ductwork and you can see the actual duct system that every system should be designed to regardless of GEO or not.
And yes I see it first hand that when you do not design to these standards as well as proper sealing of the ductwork you lose major efficiencies and COP's.
Proof is in the pudding.
One constructive point I do give is if your hitting those numbers with a sub par duct system then I would hate to see the numbers you would be seeing with the actual fittings installed. I think the reason your seeing somewhat good numbers is you must be mastic painting right much of your duct system as one should.
Like I said before I am not knocking you I am just trying to get you to open your eyes a little. We can all improve on our ways unless one thinks he knows everything even when he is wrong. And that does cut you and you customers short of the full potential.
I am so sorry that you cant understand that.
I am not designing or doing anything that others havent done before but they are just the correct methods. That's all.
How can you actually look at our ducted systems and compare it to what you have done your entire life and even come up with a legitimate argument to defend your designs versus mine. Pictures actually do speak 1000 words.
Then look at manual D and that's all the proof you need. The only thing saving you are the turning vanes. Lets remove them and we would be replacing compressors like we do behind everyone else as well as trying to fix high utility bills.
Our designs are just pure common sense and natural without any need vanes to direct airflow.
I guess when I get you here to view our Geothermal distillery we could arrange for a geothermal project to show you first hand how true custom designed sheetmetal is designed and installed.
Thanks and have a great day
EQLR= Equivalant Length of Restriction
When we design for the pressure drop across the system we should be designing to maintain a 1/2" pressure drop across your system as every HVAC manufacturer recommends.
They want and need this pressure drop. so you design the supply at .10 static for a total supply restriction equal to 100' of ductwork.
And the return is figured at a .05"w.c.
This allows for the restriction of the airflow moving thru the coils and equipment from the factory.
We design to a .03" W.c on our return static to allow for restriction of your air filter when it starts to load up. That way when it is time to be changed our customers are still running at peak efficiency. This only makes sense, So that means we design to a pressure drop of .07"w.c in our systems.
Which is going to be the new standard these so called contractor will need to follow.
But we cant even get them on board at a .05" w.c drop in the duct sizing.
This is to include all of your straight ductwork and fittings on both of the supply and return. So when you are only allowed EQLR of 100' in your entire duct system design, you can see that when people square tap a duct into another without making the proper fitting that it becomes very restrictive.
So when you can make a radius ell with a radius throat it is equal to 10-15' of duct. But when you square tap a duct into another duct without the proper fitting that one joint could have a EQLR of 90-120'. So lets add up the math when you see multiple square taps versus radius ells it can have a very bad dynamic effect on the entire system.
Supply plenum boxes on the supply side are EQRL = 190'. And so do the supply transitions that are in question in these photos.
Yet they are installed on 95% of systems installed today based on convenience and cost and not whats right and wrong. Thats why you have what you have and that's why these guys dont want to get it.
When you go to my website and see my radius supply WYE that has an EQRL 15' that still allows me 85' feet of ductwork to design to. So it's all about math and fittings to get these systems to function as they are designed to period.
Duct design is a great science to get it right and most good old boys really do not understand how to design let alone to manufacture these fittings.
We are a dying breed.
You need to invest in a very accurate mag gauge instead of those very slow vapor style you are using.
Your cfm measurements need to be 3' from any fitting or joint connection to get a true static reading.
Can you do the math on your system to see your actual cfm that your system is producing?
You are too funny! Again, any evidence? Indeed, you are a dying breed.
The only evidence I truly need are our list of references from satisfied customers when they stroke their monthly check to their utility company.
I hope you try to do a little respectful research in to manual D before you continue to feed fuel to the fire.
I will agree however your monitoring of your systems is quite unique and I do like it. And hey bro I truly feel that you are a quality guy and contractor for that fact. I am just stating my point of view as the designs we see on a daily basis in our mechanical business as well as what we see in these and your photos
Also please check out a company in AVON Ohio called National Comfort Institute.
I am good friends with those guys.
They are a relative cheap source to get on board with the proper design of highly efficient duct systems. As equipment has evolved so are the minimum standards for the design and installation of the most important part of the system which is the air delivery system.
They have a ton of data on different types of duct systems on hundreds of thousands of homes that they were able to layout the research to prove that the average duct system in this country is 56% efficient. Most of these duct systems were undersized, high static with poor duct design, leakage, everything that we see on a daily basis.
Of course we have been installing the proper designed duct systems for 20+ years. Our company motto " We set standards that others follow everyday".
I am a dying breed and proud of it!
Please let me know if I can assist you in any way shape or form in incorporating some of my designs into one of your systems and then lets monitor that system to compare apples to apples. Or as close as possible. Again I know you will see better numbers I promise.
Heck I might even sell you a job from start to finish to install in your own home.
CM Trilogy Perhaps?????
Bro it's all good as I can tell there's no changing your mind and I can tell you are trying at least, which is a lot better than most out here. I can honestly say that by looking at the few picture that I have seen. Your just missing just a little on your ducted side but again with a few slight changes we could improve that.
Thanks again for your objective thinking and difference in opinion, I am very serious so lets try one system
That will be my proof
Measured at Heatpump
Stage -CompWatts- Pump W- Pump % -Blower W -Blower % -Total -gpm -HE -COP (with circ pump and blower)
1 - 344 - 16 - 4.23 - 18 - 4.76 - 378 - 5.1 -4700 - 4.64
2 - 483 - 23 - 4.31 - 28 - 5.24 - 534 - 5.7 - 6911 - 4.79
3 - 617 - 26 - 3.82 - 38 - 5.58 - 681 - 6.2 - 8580 - 4.69
4 - 784 - 33 - 3.86 - 37 - 4.33 - 854 - 6.7 -11898 - 5.08
6 - 1133 - 53 - 4.23 - 67 - 5.35 - 1253 - 7.9 -15132 - 4.54
9 - 1718 - 85 - 4.38 - 136 - 7.01 - 1939 - 9.5 - 22577 - 4.41
12 - 2453 - 122 - 4.42 - 186 - 6.74 - 2761 - 10.8 - 26714 - 3.84
Since you are judging us by pictures, above is some steady state data for one of the systems you are criticizing and call a poor design. You indicate that many homes have undersized duct system, high static and poor design, with leakage.
The fact that we are using between 18 and 186 watts for the blower depending on the stage (37 watts at stage 4, and 67 watts at stage 6) actually indicates that the ductwork is not undersized, has low static pressure and is actually performing very well. It has minimal leakage since it is sealed from the inside via Aeroseal.
Do you have any performance numbers for your systems, including the amount of work it takes to move air through your ductwork, which is the essence of this conversation.
You got to have some data or evidence for you setting the standards others follow, especially when it is according to you the most important part of the whole system.
Separate names with a comma.