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"Seeing" Inside an Over-pumped Radiator

Steamhead
Steamhead Member Posts: 16,796
Gordon and I have equipped ourselves with FLIR thermal imagers. We're still mastering their operation, especially when "taking pictures" with them. I have to admit being skeptical when we were considering buying them, but they are proving quite useful.



This group of pics came from a converted gravity hot-water job, where we determined that the circulator was too big. The occupants were complaining that the boiler would run forever and the house wouldn't really get warm. First thing we did was service the boiler, a Slant/Fin Liberty L-40 with a Beckett AFG- and we found the usual neglect. Supposedly it was "serviced" every year- you can see they just ragged and tagged it. Note to the oil guys- this explains your "customer attrition".



That improved things, but not completely. When we started the boiler, we took a few thermal images. These were the only ones that turned out. In the first one, you can see there is warmer water at the top of the radiator (American Corto, a large-tube type), warmer water flowing along the bottom and cooler water in the middle. What had happened was we ran the boiler for a bit, stopped it for 15 minutes or so, then re-started it.



The warmer water that had been running along the bottom of the rad had convected upward while the system was off, and after we re-started it we had warm water running along the bottom again. But there was no diffusion thru the rad! With this situation, only about 25% of the rad could function as designed.



The last pic is a column rad doing the same thing. There is some diffusion in the first couple sections but most of the water is going straight across the bottom to the return connection at the right.
All Steamed Up, Inc.
Towson, MD, USA
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«1

Comments

  • Steamhead
    Steamhead Member Posts: 16,796
    edited February 2012
    With the smaller circulator

    the water is now moving slowly enough that it can diffuse thru the rad. The first thermal image was an attempt to get the same angle as before. The second shows how the water travels thru the rad from end to end when the flow rate is not excessive- it comes in from the right, travels out to not quite halfway across by which time all the water has risen to the top, then drops toward the return connection on the left. I had to leave before getting a good image of the rad heated up all the way- maybe next time we're there.



    The last image was Gordo having some fun as I checked the shutoff valve on the column rad shown in the previous post.



    This system has 1062 square feet EDR, but you could see where some the rads had been smaller originally and the piping was modified to put in larger ones. I believe it originally had 850 square feet or thereabouts, so we replaced the B&G 100 with a Taco 007. We're now circulating 19 gallons per minute rather than 27, and for the first time we can "see" the results.



    Since then I've taken some more "before" images of other jobs. I'll update this post from time to time when I get the "after" ones.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
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  • NYplumber
    NYplumber Member Posts: 503
    results

    Seeing is believing. Seeing results in an all new way.



    Which thermal imaging camera is being used for the photos?
    :NYplumber:
  • MikeyB
    MikeyB Member Posts: 696
    GPM

    Very cool Frank, how were you able to determine your Flow Rates? were you able to install gauges on the old and new pump?
  • icesailor
    icesailor Member Posts: 7,265
    Hot Rads:

    Steamhead, everything you say is absolutely true. Absolutely no questions.

    However, if you would install a Taco "I" series 4-way valve in that system. you would find that one could own the pie and enjoy eating it too.

    I have found that if you let a gravity system "run" after pumping it. the radiators have no idea **** is going on. But, with the "I" series 4-way valve, the boiler pump keeps the boiler above 140 degrees (if that is where you set the DIP switches, and the "new" system pump circulates the water that is needed. I ran one on ODR and with ODR, I went there last week when the outside temperature was 16 degrees. The system water was 120 degrees and the thermostat was set at 63 degrees. The whole house was comfortable in spite of the fact that most of the second floor radiators are disconnected. Before the 4-way, the front hall (over the boiler) would be 75 degrees when the thermostat was set at 60 and the rest of the house was either hot off cold. The boiler barely runs, drawing off the 170 degree water in the boiler. I've never cleaned this boiler. The guy who services it never cleans out the chamber. I have heard that he feels that the crud in the bottom doesn't natter. That it makes it more efficient because it reflects heat back into the flame.

    This system is LARGE. Big stand-up radiators with 4" screw pipe supply and return. All radiators are fed with 1 1/2" pipe. A lot of water. When started cold, within 1/2 hour, the entire system is the same temperature and the circulators are running merrily away. The valve is operating.

    Try one. You will not believe how well it works. If I could ever figure out how to post pictures from my camera here, I would post them. All I had to do was connect the system supply and return so it was a boiler loop and install two PROPERLY spaced tees to connect the boiler side to the valve, and connect a new circulator to the system side, and wire them together. No major re-pipe job.

    Not all oil companies clean like that. There are plenty of service persons that do the same thing. I see it all the time.
  • Steamhead
    Steamhead Member Posts: 16,796
    edited October 2016
    In the old B&G Handbooks published when forced circulation was first being applied to old gravity systems, they determined that they should size circs for 3-1/2 feet of head. This accounted for the resistance in the flow-check and air separator. The rest of the system was piped so it would circulate itself, and didn't really need any help from the circ.



    So that's the basis for my flow figures. Just look at the pump curve and see what flow it will produce at 3-1/2 feet of head.

    All Steamed Up, Inc.
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  • Steamhead
    Steamhead Member Posts: 16,796
    It's a FLIR i7

    with a resolution of 140x140.
    All Steamed Up, Inc.
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  • Steamhead
    Steamhead Member Posts: 16,796
    I'm looking at that option

    to try in my own house first. My converted gravity system has 554 square feet, currently pumped with a Grundfos UP-15-42F. 
    All Steamed Up, Inc.
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  • icesailor
    icesailor Member Posts: 7,265
    "I" valves

    You will be as amazed as I was when you try it. The system was pumped with a Taco 010. It is now the boiler pump. I used a Wilo 3-speed for the new system pump. I run it on #2 but it works as well on #1. I put temp. gauges on the supply and return to the system. It runs as close to a 20 degree delta tee as I have ever seen. All the radiators are just warm to the touch.
  • MikeyB
    MikeyB Member Posts: 696
    Flow Rate

    Thank you Frank for a great explanation, I appreciate it  
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    edited February 2012
    Your comment about slowing down water flow makes sense now...

    When you stated last week that flowing down to an emitter would increase output didn't make sense to me because I had BBR on the brain, not standing cast iron radiators.



    A word of caution as it pertains to using a thermography imager. The colorization is only a "guide" if you will, so show you where you need to do further pixel by pixel evaluation with the included software. In other words, don't depend strictly upon the visual image for analysis. In general, in the proper hands, with the proper training.education they CAN be one of the most useful tools in your truck.



    I just took a "Basic Thermography" course sponsored by my camera manufacturer (FLUE) for the 2nd time, and I learned more the second time around than I did the first time around.



    The one factor that will throw you for a loop more than anything else is the different e (emissivity) factors. If, for example in your scenario, you are looking at the radiator, the imager is seeing the lower emissivity reflectivity of shiny metal (nickel plated brass) along the higher emissivity cast iron. To the untrained eye, it will make it look like the lower e metals are cold, when in reality, they are hot. (Ever pointed a non contact thermometer at a shiny copper pipe and had a it lie to you about the actual surface temperature? I thought so...)



    There is another phenomena called "the cavity effect". Their example was looking at a shiny metal bus bar in an electrical panel. Where the allen wrench normally goes into the lugs that hold the bars, when looking at it through the eyes of the imager, the cavity looks hotter than the surrounding metal. It IS, and it indicates a problem that can't be seen from the surface images.



    Where this tool REALLY shines (pardon the pun) is in showing the consumer where a problem lies, like with a failed trap, or a failed cross connected shower valve that causes a LOT of other problems with systems as a whole. The graphic is so visual, that the problems sticks out like a sore thumb.



    I am not sure about your camera, but the evaluation software that came with my FLUKE is worth its weight in gold. The only parameter that can not be adjusted in the evaluation mode is FOCUS. If the picture is out of focus to begin with, all of your evaluations are going to be fuzzy at best.



    FOCUS FOCUS FOCUS...



    You can then adjust the back ground temperatures, ambient temperatures, and emissivity and use the cross hairs to show point temperatures, or a box to show average temperatures and so on and so forth. You can then transfer what ever image that is in your evaluation to a JPEG image, and use it in a report. So you can show them what it looks like in normal light, and then what the same image looks like in the infrared spectrum.



    There are the equivalents of "The Wall" out there that are run and attended by people who use these cameras for a living. You can learn a LOT about the use of this tool by hanging out at these web sites.



    I have literally THOUSANDS of images that I have collected over the years with mine.



    A final word of caution. Do NOT leave the camera in a cold environment, and then take it inside a warm humid environment. The humidity that forms on the IR sensors will scramble the picture. That pretty much applies to ANY delicate electrical instrument, but everyone already knows this, right :-)



    Enjoy



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Steamhead
    Steamhead Member Posts: 16,796
    edited February 2012
    Obviously we're still rookies with these things

    but even so they're eye-openers. I should mention that when we took these images we had watched the rads start to heat up and followed the water as it flowed across the bottom. Have to remember to take more images on the next ones, to show this.



    The radiators in question were painted and so were the pipes supplying them. That might at least partially equalize the emissivity of the pipes versus the rads.



    Regarding baseboards- yes, I've seen them over-pumped too. We've slowed the flow thru these units and gotten more heat out of them. It's probably harder to over-pump baseboard than old gravity rads,  though- regardless, we'll take some FLIR pics of the next ones we run into.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
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  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    edited February 2012
    Absolutely true...

    Painting a surface will dull its emissivity, thereby showing true surface temperatures.



    I've resorted to painting spots on bright copper pipes with teflon paste dope to get a better idea of the surface temperatures.



    It just takes time and experience with the software and the camera to add competency to your IR skill sets. Just wanted to make sure that everyone reading this understands to not put all their faith in the color palette.



    BTW, I assume that is Dr Schweizer in the one picture, because there is no pony tail showing :-)



    Tell him he is running a little cool for a steam powered mechanic ;-)



    Good job of educating Frank.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • bob_46
    bob_46 Member Posts: 813
    Pump Logic

    If you take this logic to the extreme you get maximum heat transfer with the pump off. What flow rate gives maximum output of a length of baseboard , a rate that gives a delta T of 100F or a rate that gives a delta T of 1F ? Are we to use the GOLDILOCKS method of pump sizing ?
    bob
  • Steamhead
    Steamhead Member Posts: 16,796
    Dr. Schweizer took that image

    it was I who was crouched by the rad. I never had a ponytail- you must be thinking of Noel or Boilerpro.
    All Steamed Up, Inc.
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  • Steamhead
    Steamhead Member Posts: 16,796
    edited February 2012
    Good question

    and I don't have the answer. I do remember that when I was trying different circs on my own system, when I tried the little B&G NRF-9F/LW the flow dropped to the point where the rads at the ends of the mains didn't heat well. So I guess that would be the practical lower limit.



    Remember on a gravity system as originally installed, the flow rate would vary with the water temperature. With a circ we can maintain flow regardless of temperature. Our target is to maintain flow at the highest rate it would have been on the coldest day of the year, even on the mildest days, but not to exceed that rate since it can produce short-circuiting thru the rads.



    I think baseboard is more forgiving, but have still seen it over-pumped- though less often than on gravity conversions. But now we're in a position to "see" this as well.
    All Steamed Up, Inc.
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  • scott markle_2
    scott markle_2 Member Posts: 611
    edited February 2012
    base output

    I don't see how you could over ever pump base board to a point where the output would go down. Flow and temperature are not a linear relationship there is no flow that will provide a delta 0.



    With base it's visually obvious that a low delta will mean larger hot radiator surface area, thus higher transfer potential.



    Your saying that these images suggest that the natural convection that happens in the individual sections is adversely effected by high turbulence through the bottom of the rad, thats interesting...I would think Dan might have something pre thermal imaging that supports this idea of over-pumping and reduced output. Do you think this is a significant effect on output? could the pictures be exaggerating the actual effect.



    It would be good to put the over pumping (reduced output) myth to rest, but this is compelling evidence of an exception.
  • Steamhead
    Steamhead Member Posts: 16,796
    edited February 2012
    The shortest distance between two points

    is a straight line. And given enough force, that's how the water flows thru the rad. So it's not a myth, and now we can "see" it.



    In a system designed for forced circulation, both of these rads would have been fed with 1/2" pipe, not 1" or 1-1/4" as on a gravity-designed system. The velocity in the 1/2" pipe would quickly dissipate as it entered the relatively wide-open rad, allowing the hot water to diffuse within the rad.



    But on an over-pumped gravity conversion, the larger pipes allow the velocity to continue thru the rad in a straight line without much diffusion. This results in short-circuiting.



    This is the hot-water equivalent of steam boiler pressure settings: Above a certain point there is no benefit from higher flow, and it's very possible to have too much flow.



    Again, we haven't had a chance to take thermal images on a baseboard system. But we will.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
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  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    The shortest distance between two points

    There is a similar saying I like very much.



    A short cut is the longest distance between two points.
    Tinman
  • icesailor
    icesailor Member Posts: 7,265
    Overpumping:

    Steamhead,

    That's the best explanation of over pumping I have seen. It fits perfectly to what I see in over pumped systems.

    Like pouring a 5 gallon bucket of water on a floor or squirting the 5 gallons through a small hose onto the floor. One slowly spreads out and covers an area. The other squirts across the floor and until the velocity drops, it can't flow over the floor. Both with the assistance of gravity.

    If that makes sense to you.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    My mistake...

    Could have sworn you had one. my bad...



    Maybe we should ask Dan to set up a new section called Infrared Thermography where we could exchange images and explanations. I've got LOTS of different images to share. With the costs coming down, more and more people will need this kind of useful information...



    I'd love to see an end view of a gravity feed 3 column radiator showing the natural convective patterns at work.



    I have some of a panel radiator heating up that is pretty interesting. I also have lots of pictures of radiant windows as well, but they are SO consistent that they are boring...



    What thinks ye fellow Wallies?



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Steamhead
    Steamhead Member Posts: 16,796
    edited February 2012
    Dan?

    What say ye?



    Meanwhile ME, why not post a couple to whet our appetite?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
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  • Steamhead
    Steamhead Member Posts: 16,796
    It does

    time to start stocking some smaller circs!



    On my truck I have a Taco 007, Taco 005, Grundfos UP-15-42-F and B&G NRF-9F/LW. This way when I encounter an over-pumped system I can fix it then and there, assuming it has standard flanges.



    Multi-speed circs can reduce inventory, but people can mess with them. So I use single-speed on gravity conversions (and smaller forced systems) to avoid problems and callbacks- once the flow rate is set, it stays where it is. The exception is if there are zone valves or a lot of TRVs, where a ΔP circ makes sense.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Bob, what pray tell is the Goldilocks principle.

    Feed a wolf, starve a fever.



    I suspect it has something to do with a short cut but wanted to clarify it with the author.



    Thanks



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Steamhead
    Steamhead Member Posts: 16,796
    Good one!

    hadn't heard that before. I'll make good use of it.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    I'm betting...

    That one or two IR camera manufacturers would be interested in sponsoring an ad for that area to help defer costs :-)



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • NYplumber
    NYplumber Member Posts: 503
    cautiously asking

    Cautiously asking, what's a radiant window?



    Let's see pics please.
    :NYplumber:
  • bob_46
    bob_46 Member Posts: 813
    Goldilocks

    I'm not sure what it means , it just popped into my head. Let's see , this bowl of porridge is

    too hot , this bowl is too cold and this bowl is just right. I just picture a tech with a pile of

    pumps on the floor next to the boiler saying to himself well I think this radiator is putting out more heat with the green one.
    bob
  • bob_46
    bob_46 Member Posts: 813
    Interpret

    Frank, I wonder if the thermal images accurately show the flow of water , or of the flow of

    heat ?
    bob
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Thanks for asking Moe....

    This is a WONDERFUL product that I'd been exposed to about 5 years ago. When first approached, the original group basically had a window that when you plugged it in, it got hot. No controls, no knowledge of input versus output, and no real idea of how to properly apply them. I spent about 3.5 to 4 years working with that group (at no charge) coming up with different applications, different means of controlling the windows, and suggestions about how we could enhance the product. Unfortunately, that company ran into hard times, and is struggling to even keep their heads above water...



    I was so enamored with the product that I continued my research and applications. I have two houses in the mountains that have them incorporated in the overall comfort designs. I have found that the ideal temperature of operation in the long run is 70 to 75 degrees F. That way, when you are sitting or standing right NEXT to the glass, your body can not "feel" the window any more than it can "feel" the other surface temperatures within the room (think HUGE MRT influence here...)



    The windows are UL listed for up to 115 degrees F operating temperatures, and in that mode CAN be used (under the right conditions) as the whole house sole source of radiant heat. We have a couple of homes that are being heated primarily by the windows. Not suggested in my book due to inefficiencies at elevated temperatures (15% back loss to the outside air) and the associated cost per therm (Electricity = $2.00 versus N.G. @ $0.50 and propane someplace in between, and in some remote areas LP is MORE than electricity, hence the few applications that we have where N.G. is not available). Plus, as KSU proved, the lower operating temperature produces a higher degree of radiant energy input into the room, and lesser amounts of convective energy input, which works better for raising the MRT within a given room. Lower is better for sure.



    But they can also be used to "accelerate" the MRT in situations whereby the home is kept at low (40 F) temperatures during unoccupied conditions (like my weekend home in the mountains for example), and needs to be turned up prior to being occupied. Kinda like putting the pedal to the metal if you know what I mean....



    So, I had to move beyond the original company that introduced me to the idea. Unfortunately, they had a GREAT idea, and a good and robust means of doing the heated glass, but they only had UL approval for up to 48 vDC power. I kept telling them that if they wanted to get into the LARGE glass market (think commercial buildings) that they needed to go back to UL and get a control and their glass certified for higher (120 VAC) power. This required a complete rethink/design of their controls. Unfortunately (for them) they hired (actually self appointed...) a CEO who decided he knew more about the windows and controls than the core technical group of co-inventors and myself, and shortly after coming aboard, he decided that we were not "team" players, and cut us out of the picture as it pertains to decisions regarding the control. I wish them the best of luck in their future.



    Moving on, I discovered another local company that had already patented and gotten a UL approval for a control and window that that required no low voltage thermostat wiring (wireless controls), whose products were tested and rated for 120 VAC and the owners were willing to listen to my recommendations as it pertained to these controls, and their applications.



    I am set up as a manufacturers rep for them, as well as being a dealer. I have made a major decision that this is going to be the year of the Radiant Window, and am going to do everything in my power to make this product a standard in homes with large amounts of glass in close proximity to humans at rest.



    We are looking to apply the radiant windows not only in situations where human comfort is important, but also in areas where condensation production on the glass is an issue (hospitals and natatoriums) as well as sloped glazing on green house rooms, where snow/ice fall can be a major hazard to pedestrians and many other non human comfort applications (think heated windshields on HumVees with ultra thick explosion/armor proof glass that can't easily defrost the glass with just the inside blower that is typically used to maintain a clear wind shield) as well as keeping lizards, snakes and other cold blooded pets warm :-)



    I am on the wrong (Mac) machine to be able to give you an IR photos of the radiant windows in action, but will switch machines later and show you what a heated window looks like right next to an unheated window and see which one you;d rather be seated next to.



    Oh, didi I mention that if these are used with Solar PV that one could actually pump sun shine into the north facing windows thru the wires of their homes, thereby putting sunshine where it has never shone before, and that if wanted, this energy can be "banked" in the north facing rooms, raising the MRT to allow dissipation through the night until the sunshine starts falling again?



    In the 36 years that I have been doing this human comfort thing, this technology represents the BIGGEST advancement in technology that I have ever seen, bar none.



    Stay tuned... and feel free to ask questions.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Steamhead
    Steamhead Member Posts: 16,796
    They show

    the flow of warmer water thru a rad starting at room temperature. Remember, these are snapshots. Eventually the rad heats fully and remains in that state until the flow stops.
    All Steamed Up, Inc.
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  • don_9
    don_9 Member Posts: 395
    convection

    Hello Frank.I wonder is it possible to show a pic of a rad with a 68 degree room temp with a 007,then one with a 005 with a 68 degree room temp.

    I would think the faster air thru the rad would give off more heat and make it red all the way up verse one where the air is cooler and less dense giving one less heat more blue if you will.just another equation to add to the math.lol
  • SWEI
    SWEI Member Posts: 7,356
    radiant glass

    This needs its own thread - want to learn more!
  • Steamhead
    Steamhead Member Posts: 16,796
    edited February 2012
    I might have to set that experiment up on my own system

    which I never seem to have time to mess with these days- too much work, but I guess I can't complain ;-)



    Remember, the pump size for a given system will depend on the amount of radiation on that system. So for a certain size of rad, a small system might need an NRF-9F/LW to circulate that rad, but a larger one might need a 007 or whatever.



    Whenever I post about this, I'll be sure to mention the amount of radiation on the system.
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  • bob_46
    bob_46 Member Posts: 813
    Re-invent wheel

    Frank, I found some research that may save you a lot of time. The conclusions confirm

    your findings. I would have bet you were wrong but you nailed it. This whole pdf is pretty interesting .As regards over pumping see page 33.
    bob
  • Steamhead
    Steamhead Member Posts: 16,796
    edited October 2016
    Interesting!
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  • Steamhead
    Steamhead Member Posts: 16,796
    edited March 2012
    Some more examples

    These are from a very small gravity conversion we worked on today- 255 square feet EDR. Boiler had a Taco 007.



    First thing we found was that most of the radiator valves were turned off- no wonder it took forever to heat the place. When we opened them, we found the usual short-circuiting. We took some images, then switched to a B&G NRF-9F/LW



    This pair of pics shows a small-tube rad, connected top and bottom on the same side. In the first pic, we see the water running thru the inner cast-iron tubes but not diffusing properly thru the outer ones, as noted in the Illini report Bob cited. The second one shows the improved diffusion after the circ change- there is less contrast between the inner and outer tubes.
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  • Steamhead
    Steamhead Member Posts: 16,796
    edited March 2012
    Here's a column rad in the same house

    connected bottom-to-bottom. In the first pic, the water is shooting across the bottom from right to left, with just a bit of diffusion. The second pic shows a noticeable ∆T between supply and return, with good diffusion in the first several sections.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
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  • Steamhead
    Steamhead Member Posts: 16,796
    edited March 2012
    And some Dead Man got it backward

    we found a couple rads connected top-and-bottom where the hot water actually came in the bottom. Oops! Fixing this will have to wait for another day.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 3,976
    edited March 2012
    To tell you the truth

    both pictures look the same to me - but I'm just though with dinner and had a bottle of claret. 



    The second image shows the same diffusion, but at 15F lower temperature.  I'd put back the 007.



    Edit: Oh dear, the pictures have changed - I should know better.  Great job, Frank.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Steamhead
    Steamhead Member Posts: 16,796
    edited March 2012
    You have to look closely

    at those first two pics. The difference in temperature when they were taken actually highlights the issue. In the first pic, the rad had had time to warm up more, but the outer tubes had much less circulation than the inner ones and the contrast is notable.



    In the second one, the measured temperature is less, but the water is flowing more evenly thru the rad as evidenced by the lesser contrast between inner and outer tubes. There is still some contrast, but not as much as before.



    I might not have been looking for this were it not for Bob posting that report.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
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