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radiant heat loss because of pex placement?

2

Comments

  • Zman
    Zman Member Posts: 7,610
    Ohm the sensor

    It looks like you have this thing on the run. If your sensor is consistently off, you can isolate the sensor and check it with an ohm meter. This certainly could be contributing to your problem. Keep in mind the outdoor reset curve is different for every project. Taco programed a "starting point" when they shipped your mixer. It is up to the installer to "tweak" it for a particular job. 
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • panman
    panman Member Posts: 82
    re- OHM sensor

    Zman, what sensor are you talking about? Yes, i feel like i am getting somewhere thanks to people like you, Gordan and others that have taken time out of your schedules to aid me in this dilema. (much appreciated). I think a few tweaks and pulling the carpet and i will be in good shape. My local propane company has good techs, but do not seem to have the expertise that a few of you have on this site. Thanks again-Peter
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    why the outdoor temp reads 15 degrees warmer than the acual temp

    Here are a few possibilities.



    1.) My boiler has an adjustment I can make to correct for what the outdoor sensor (a thermistor) thinks is the outdoor temperature and what I think is the outdoor temperature. If this is adjusted incorrectly, I could get a difference. Mine will go from -10F to + 10F. Yours may go farther.



    2.) If you have a defective thermistor, or the wrong thermistor, you could get erroneous readings.



    3.) If you used wire that is too long or too small (gauge), that could cause it to read lower. I do not think this would cause it to read higher.



    4.) If you run the thermistor wire too close to a power line, you could get unexplicable readings.



    Sensor underneath a deck? Does vent pipe run anywhere near it?
  • Zman
    Zman Member Posts: 7,610
    Sensor

    Peter,

    There is an outdoor temperature sensor hooked to each of your mixing blocks and running outside. If the sensor is giving the mixer bad data that will mess with your temps.I would start be putting an know accurate thermometer in the same area as your outdoor sensor. If you still see a 15 degree discrepancy,  I would then disconnect the sensor from the mixer and then check the ohms between the 2 wires. The manufacture can tell you what resistance you should be reading at a given temp. I think the possibility of AC power interference mentioned here is valid. removing the sensor and testing it individually will eliminate this. Keep in mind that handling the sensor will  warm it up and change the output temp.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • panman
    panman Member Posts: 82
    nest on outside sensor.

    I just went outside and checked the sensors. I found out one of them had a birds nest built on top of it. Knocked it off and we shall see if that helps. Thanks for getting me thinking Jean-David. Thanks-Peter
  • panman
    panman Member Posts: 82
    adjustments to mixing blocks

    Zman or Gorden, I am posting photos of the results of all zones running when the temp out is -14, Brrrr. Note that upstairs is being met just fine, and down stairs temp was 64. Please advise on any ajustments i can do to the mixing block menu. Thanks-Peter
  • panman
    panman Member Posts: 82
    adjusrments

    I posted some operating temps of both floors when all zones were running. Take a look at what i wrote on sunday and let me know if you would make any adjustments to basement mixing block. Thanks- Peter
  • Gordan
    Gordan Member Posts: 891
    Let's try this

    On the upstairs zone, change design mixing supply to 130 and max mixing supply to 135. Yes, we're actually dropping it a bit, since it's keeping up at lower temperatures. The reason for this is that we don't want it to be too greedy and steal more hot water from the boiler loop than it actually needs (leading to quicker zone satisfaction upstairs but more lag downstairs, which is the one with a problem.)



    On the downstairs zone, change design mixing supply to 140 and max mixing supply to 145.



    On the BOILER, change the HI setting to 150 and the RES setting to 85. (See section 8.0 - Sentry 2100T Controller - of the attached manual.) What are they at now? How does the boiler outdoor temp sensor read, compared to the ones at the mixers?
  • panman
    panman Member Posts: 82
    re let's try this

    Gordan, thanks for getting back to me. I will reset those settings and let you know what the boiler info read before i adjusted them. Thanks again-Peter
  • Gordan
    Gordan Member Posts: 891
    Please post the new readouts from the mixers

    ...after you change the parameters and the system's been running awhile, all zones calling.
  • paul_79
    paul_79 Member Posts: 91
    radiant heat

    i don,t  know if any one has asked this question but what is the setting of the trinity boiler hot water supply?  is it set as a low temp condensing boiler setting of 130 or so, or is  it at a 1 80 or so boiler loop temp. my thinking is if it is set a  130 or so temp then the Rmb  will not have enough for the mix even at full speed.
  • panman
    panman Member Posts: 82
    Re paul

    I am checking the temp on the boiler. I have to figure out the function and menu operation first. I am not a boiler tech, so i did not dare to mess with the boiler menu last night. Maybe in a day or so!!!! Thanks for your post-Peter
  • Gordan
    Gordan Member Posts: 891
    It's in the manual I attached

    The "HI" and "RES" settings jointly determine the outdoor reset operation. The boiler will produce "HI" at 0 F and below, and "RES" at "RES" F and above. Judging by what your mixers are sensing, "HI" is 130 F right now.



    The "LO" setting is for your indirect.
  • panman
    panman Member Posts: 82
    Attached manual

    Gordan, i have that manual at home. I went to change the boiler temp on the HI to 150 and The RES to 85 like you said, but did not feel confident enough to make changes to the boiler. If it were summer i would not worry so much, but being january, i really need the furnace running. I'm sure it is an easy adjustment. Thanks-Peter
  • Gordan
    Gordan Member Posts: 891
    I understand your reticence

    Though, really, it's no different than tinkering with the mixing station parameters. (And the latter, at this point, won't do much good without warmer water from the boiler.)



    Anyway, whenever you muster the gumption to do it, please be sure to report your results and post what the mixing stations are saying!
  • panman
    panman Member Posts: 82
    Boiler readings

    Ok Gordan, I came home and figured out how to read the boiler settings. I am a little puzzled at the temp settings but here it goes

    Hi- 190      Lo- 153       Diff.- 20      Res.- 80

    SF5-82    HF5- 240     LF5- 45  ER5-  ON

    I did not see an outdoor setting temp. Hope this helps. Thanks so very much for you time and expertise!!! Peter
  • Zman
    Zman Member Posts: 7,610
    Check everything

    I got to thinking on this. What kind of lunatic puts mixing blocks on a modcon boiler that already has outdoor reset? Both floors should be able to run at the same temp directly off the boiler. The boiler never fires hotter than it needs to and runs at optimal efficiency.Those mixing blocks are $1,000 bucks each!

     That being said I think you need to check everything. It looks like you have 1" main lines. That seems small for a 199K BTU boiler is the boiler a 200? What size is the boiler pump and what speed is it on? Are those 1/2" lines going into the blocks? Are the block sensors strapped to the correct pipe. Start  feeling the pipes. Are the pipe attached to the lower (undersized) headers at the same temp?

    Your symptom is cold floors, the pex placement is not helping. There is something else going on.With those boiler settings you should be able to get the temp up. Is the boiler really getting that  hot? Does it have a gauge?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • panman
    panman Member Posts: 82
    re-check everything

    Zman, My boiler is a Trinity 200 propane on the wall as you can see in the pics. The copper piping from boiler to mixing blocks and manifolds are atleast 1''. Pex tubing in the floor are 1/2''. My floors are not cold, the upstairs zones are warm and being supplied fine. The downstairs concrete is warm at times and the area temp is met most of the time until colder weather but the down stairs zones hardly EVER shut off. The water temp is always mixing around 110-120 for down stairs zone. I think if it were running at a constant 130-140 plus take up the carpet and pad, it would be 90% better. The sensor straps seem to be on the right pipe and the boiler temp gauge last night was running around 167 at times with just the down stairs zones running, but the mixing block was only putting 110-120 degree water into the slab. Everything seems to check out. Thanks for the input- Peter
  • Zman
    Zman Member Posts: 7,610
    Good

    OK Good,

    That eliminates some potential bottlenecks. I assume the out put to the lower level does not change regardless of what the upper level is doing.(the upper zone is not stealing all the heat) ?

    Are you comfortable that the zone controller is set for the higher temp, and you are not getting it?

    What I am saying is if you have good flow and high temp in the main pipe going past the  mixing block and you can't get the mixing block to inject that heat into the radiant loop,  it may be time to call taco and get some tech support. You may have a issue with the block
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Zman
    Zman Member Posts: 7,610
    Piped backwards

    It looks like the mixing blocks are piped backwards. If this is the case they are reusing much of the water they are supposed to be sending back to the boiler. I think this is the entire problem. Check the manual and the direction arrow on the main pump
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • panman
    panman Member Posts: 82
    re-piped backwards

    Zman, the mixing blocks are correct in there water flow. The hottest water is pumped out the bottom of the block and returns into the top. In a normal case radiant heat scenario, the concrete slab in the bottom floor would run 85-100 degrees and aluminum finned under the floor would run 130-150, so the mixing blocks would be the ideal setting. Where my pex tubing is under the slab and carpet on top of the slab, the previous home owner(builder) could have ran a straight 130 degrees into the pex on both floors and eliminated the mixing blocks. Maybe some day that may be an option for me, but i do not want to jump ship just yet. thanks for your time and input-Peter
  • Zman
    Zman Member Posts: 7,610
    Backward

    Take a close look at page 2 and 15 of the manual. Then look at the arrow stamped on the grudfos pump. I am certain they are backwards. I live in house with tubing place to deep and with inadequate insulation underneath. I do have the correct carpet padding. I need 130 degree water on the cold design day to make it work. I have also done the the calcs in the textbooks and come to the same conclusion.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Zman
    Zman Member Posts: 7,610
    Arrow on the casting

    It is possible they turned the motor when they installed the pump. if it is pointed down you are OK if it is up it is incorrect
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • panman
    panman Member Posts: 82
    re-arrow on casting

    Zman, i will check the arrow on pump tonight. Thanks
  • Gordan
    Gordan Member Posts: 891
    It's unlikely

    If the boiler temp sensors on the mixing stations are to be believed, the one for the downstairs zone is cooler than the one for the upstairs zone, suggesting that the circ is upstream of the mixing stations.



    But, then, the upstream mixing station is also reporting 129 F as the boiler loop temp downstream of the mixer, which is just about impossible if the boiler is making 190.



    Panman, this is not going to go anywhere unless you become a lot more comfortable with checking things, and follow the suggestions of those who are trying to help you. That means getting a contact thermometer and taking water temperature measurements already... it also means changing the mixer parameters as I suggested, and it also means checking out whether your outdoor sensors are good or busted. If that sounds like a bit much, and I'm not suggesting that it shouldn't be, you really need to get someone on site to fix this for you. It's not impossible to diagnose remotely, but it requires a reliable and capable set of remote hands and eyes. You've got a system with a lot of moving parts, and we're not getting very far nailing some of them down.
  • panman
    panman Member Posts: 82
    re-it's unlikely

    Gordan, If i understand your message, you see something wrong with the systems flow of 190 degree boiler water? Gordan, what would be wrong with by passing the mixing blocks down the road and have 130-140 degree water flow through all the zones calling for heat? Thanks for all your help. I will seek to get someone on site. You have been so very gracious in helping. Thanks-Peter
  • Gordan
    Gordan Member Posts: 891
    I would think that 190 would be higher than necessary

    But no, what I'm getting at is that I don't believe that the boiler is making anywhere near that high a temperature. Based on the readouts you provided of the mixing station sensors, I think it's making 130 or so. You should be able to read it out from the boiler's display (water temp light is lit, should be showing the temperature in the display); you should also be able to read out the sensed outdoor temperature (air light is lit.) If the boiler doesn't automatically cycle between displaying these values, you may need to hit the up or down arrow keys until the correct light is lit.



    You should also be able to confirm it with a contact thermometer, by touching piping at appropriate points (boiler supply outlet, return outlet.) A simple digital kitchen thermometer that you can get at your grocery store for twenty bucks, and then use to make sure that you're not overcooking your roast, would be plenty good. Better than going blind, for sure.



    There's nothing wrong with bypassing the mixing blocks once your boiler is set correctly. You can't just pull them out, but have to replace them with circulators, properly piped and wired through relays. Not much work for a pro.
  • Zman
    Zman Member Posts: 7,610
    Narrow it down

    I have to agree with Gordon.You have to narrow down your problem. You have to know for sure that you have good flow in the correct direction and adequate supply temp. Never assume that because you "believe" the water is going the right way, that it is. By the same token, just because one gauge in one location is indicating a certain temp that the whole system is that temp. Measure it! Once you are absolutely positive that  you have flow and temp then start looking at the mixing blocks. I think 190 degree water for troubleshooting is fine. Eventually I would like to see either no mixing blocks or a boiler curve set slightly above the highest temp block curve. Unless you can get into this troubleshooting mind set you are going to continue chasing your tail.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • panman
    panman Member Posts: 82
    edited January 2012
    190 degree water

    Gordan, the boiler water was jumping between 160-170 when heating my DHW a few days ago. I have a co-worker that has a temp gun that will get me a close estimate. What boiler efficiancy would i lose if the system was set up to pump 130-140 degree water into the zones without the mixing blocks. In my case of needing closely the same temp for upstairs and down, i fail to see the need for mixing blocks. Would the boiler keep up? Would YOU eliminate the blocks if it were your system?PS, my circulator is set on med. setting!!!  Thanks for your thoughts-Peter
  • Gordan
    Gordan Member Posts: 891
    edited January 2012
    So we just need to know what it's showing during space heating

    You wouldn't lose any efficiency by eliminating unnecessary mixing - you would gain efficiency, and lose unnecessary complexity(and potential sources of breakdowns and - once things break down - of difficulties in troubleshooting. As we have seen. :-)



    BUT - and this is a big but - even though they may not be necessary in your system, I don't think they're the source of your problem - or at least not the sole source. They may not be optimal but they shouldn't stop the system from heating properly. What I've been trying to do is get your system to a working state without major surgery, so at least you're comfortable, and then leave you with some suggestions for improvements based on what we find out.



    When you get that thermometer, measure at the following points (while everything is running):



    - outdoor temperature (point at some object close to where your outdoor air sensors are, but not the house itself)

    - piping exiting the boiler that goes to the red circulator (hopefully the supply)

    - the other pipe exiting the boiler (hopefully the return)

    - boiler loop piping on either side of each of the two mixing stations' closely spaced tees

    - all four pipes going into each of the two mixing stations

    - the exhaust flue pipe on the boiler (the hot one)



    Now, if you're using a point-and-shoot thermometer, wrap a couple of inches of the pipe in black electrical tape and shoot it from up close, or you won't get a good reading. That's a total of sixteen measurements and it should be taken in close sequence (so, put the tape on first and then take all the measurements.)



    You also need to check what the boiler is reporting as the water temperature and the (outdoor) air temperature.





    In addition, sample the floor temperature at multiple locations in the downstairs rooms and post those as well.



    Believe me, those measurements should tell us a lot about what's really going on.
  • panman
    panman Member Posts: 82
    Re-heat temp gun

    Gordan, I will try to get all the info that you wrote down. thanks for being so thorough. Thanks - Peter
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    outside of the radiant system

    Gordan is doing a great job walking through the radiant with you... I won't go there and interfere, but keep on with him, he's bringing you to where you want to be with what you have as far as settings and like goes. Nice work Gordan!



    but a couple of other questions, just in case. I'm suspicious about this drop to an apparently constant 64 degree room temp at any temp under a somewhat predictable outdoor temperature threshold:



    1. what are you normally maintaining for a room temp in the basement area before it drops to 64?

    2. do you have any air equipment in the house? Say, like an HRV/ERV? if so, specifically what, and is anything dedicated to the basement or primarily directed at the basement?
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • panman
    panman Member Posts: 82
    re-outside of the system

    NRT_Rob, I want to clerify the 64 degree drop is a gradual drop as the temps get colder. The room is set at 72. Between 10-30 degrees the down stair zones are running all the time and do not get the room to 72. When temps are 10 to -20, the system down stairs can't keep up and temps have dropped to 64. We have no air equipment in the home. Thanks for your input. I will know more tonight when i get all of the system temps as Gordan has stated. Thanks
  • panman
    panman Member Posts: 82
    Gordan- heat gun results

    Ok, Gordan, here we go!!! The maine temp at the time of the reading was 19 The gun results were 14 as you can see.The mixing blocks outside temps were 25. The boiler was telling me that the water temp was 170 at the time of the reading. With all the zones open the mixing blocks were not above 115-120. The results of the info are on the photo. PS- The electrical tape does make a good 10 degree difference!!!!!! Thanks -Peter
  • Gordan
    Gordan Member Posts: 891
    Two things jump out

    1. If the boiler's sensing 170 degrees (this would seem to support the HI setting, as well) and actually producing 125 degrees, there's something wrong with the boiler. The sensor could be broken (there's information on how to test it in the manual) or there could be local hot spots where the sensor is located, owing to restricted flow inside the heat exchanger (this depends on whether the supply sensor is in the exchanger or on piping.)

    2. The exhaust temperature seems too high for the return water temperature. This could also be due to there being something up with the heat exchanger, or inadequate flow.



    What's the model of the red circulator? Does it have a speed selector on it? What speed is it on?
  • panman
    panman Member Posts: 82
    re-two things jump out

    The circulator is a groundfos. It is set on med. Thanks peter
  • Zman
    Zman Member Posts: 7,610
    Which one?

    Of course it is a grundfos. Is it a 15-58 or 26-99? Which way is the arrow stamped on the pump pointing?Is the the pipe size 1" or 11/4". You are positive the the boiler is a 200. Not a 150 or 100?The look the same from the outside. This is really important with a high head boiler. 
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • panman
    panman Member Posts: 82
    re-which one

    Zman, The arrow on the circulator is pointing down. All the boiler manuals that came with the boiler say it is a 200, but i can check if you give me something to look for on the boiler to clerify that it is a 200!!!!! As far as the groundfos model # and pipe size, i will check tonight. Thanks-Peter
  • Gordan
    Gordan Member Posts: 891
    Grundfos makes many circulators

    Hopefully yours is an UPS 26-99FC. Can you confirm?



    Also, are you absolutely sure that what you were reading off the boiler display was the temperature? Was the left-most LED indicator under the display on when you were reading off the value? If it was the third one from the left, you were actually reading gas input.



    Please confirm those two things. Then, do the following test. During space heating, once boiler temperature stabilizes (not bouncing around much - use your IR gun to measure boiler supply and boiler return) then take down the boiler supply, boiler return, and flue temperatures. Then kick the circulator to high speed, wait until things stabilize again, and take another set of supply/return/flue measurements. Also watch what temperature the boiler is reporting on its display, both before and after the speed change, and post that too. Make sure that you're taking down the boiler water temperature and not something else.



    You haven't told me what outdoor air temperature your boiler is reporting, compared to an IR gun reading. This is important. The second-from-left LED under the display will be lit when the outdoor temp is being displayed.
  • Zman
    Zman Member Posts: 7,610
    input btu

    There will be a model number as well as the input btu plate somewhere on the boiler. Modcons can be fickle about flows. I am trying to rule this one out.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
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