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Fins for Pex pipes?

it1991it1991 Posts: 4Member
Hi,

I am new to this so I apologize for any incorrect terminology :)

Background: I recently bought a home about two months ago. Just moved in and noticed the heat wasn't quite reaching the expected temp. Never can really get above 69 in the downstairs, which is okay with me but a bit cold for the baby. I did some research and tweaked the outdoor reset which helped a little but overnight when it got cold, it looked the like boiler kept cycling. I had a professional come out this morning and he changed the parameters on the boiler so that it does not drop below 150 even when cycling.

Problem: This helped significantly in the living room but still have problems in some other rooms. Upon further inspection from the heating company, they noticed that some of the pipes in the baseboard are Pex not copper. In addition there are no fins on them. For example, the office has about 16ft of baseboard. 6ft have fins, 10 do not. Why? I don't know.

Question: Can I buy fins and put them on Pex piping? I saw that there are fins for copper but could not find any for pex. Are they the same, or are they special for Pex?

Details: Boiler GB142. Outdoor reset AM10. House is on Slab with hot water basedboard. There is hotwater running through the pex even in the colder rooms. However it is not as hot as the areas that have fins.

Please let me know if you need any additional details. Thank you so much for any help.

Comments

  • Jamie HallJamie Hall Posts: 10,284Member
    I doubt very much that you'll find fins for PEX. The proper solution to the problem is to replace some of that PEX with proper finned copper baseboard. Figure out how much heat you need in that space, and then add baseboard until you have enough.
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • GordyGordy Posts: 9,264Member
    Well now......

    Wondering what the thought process was on that..... baseboard covers to hide pex, or someone just thought it would work? Which it apparently does not.

    Option 1 only, best, and right option is to buy the correct amount of baseboard to make up the length that only has pex. One should do a room by room heat loss first to verify how much baseboard is needed to make up the deficit.

    No they don’t make fins that would go on the pex. Pex is a poor conductor of heat compared to copper, and aluminum any way. They do make 4” wide aluminum heat transfer plates for radiant heating, but I don’t think it would fit in the baseboard cover , let alone get the correct convective air flow through it to do any good.

    Stick with option 1


  • it1991it1991 Posts: 4Member
    Thank you for your responses.

    someone thought it would work... I reached out to the guy who did it and said he did a heat-loss analysis and that the right amount was put in... oh well. too late to question it now.

    Any idea how much it may cost to replace the plex with copper baseboard? I assume this isn't something I can do myself as I don't have any real experience with plumbing/heating.
  • GroundUpGroundUp Posts: 483Member
    We don't talk cost here, but it should be relatively inexpensive. Probably not much more than the service call this morning, seeing as the cover is already there. Element is cheap and if everything is already there, it's as simple as cutting the pex back and replacing the pex with element
  • GordyGordy Posts: 9,264Member
    edited February 28
    One thing to keep in my in mind of increase the amount of baseboard it would pick up a few efficiency points. If you can get return temp below 130 degrees.
  • neilcneilc Posts: 659Member
    Do we know it's a condensing boiler?
    what boiler? make and model?
  • GordyGordy Posts: 9,264Member
    GB 142
  • neilcneilc Posts: 659Member
    I gotta learn to read, everything.
  • JUGHNEJUGHNE Posts: 5,579Member
    If some baseboard elements froze and split, then the easy fix would be to cut the bad out and stick pex in to complete the circuit.

    Seems doubtful someone would install the extra cabinet/covers
    for length display and put pex in it. (could be a date code on the pex??)
  • hot_rodhot_rod Posts: 11,259Member
    You may in fact have enough fin tube in the rooms and just need higher supply. typically fin tube is sized at 180F for design. If you only supply 150, output is decreased. Possibly the previous boiler was a non condensing type supplying 180 SWT?

    Do a room by room load calc with this and compare to the fin tube output data at various SWT.
    https://www.slantfin.com/products/virtual-heat-loss-calculator/
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • BrewbeerBrewbeer Posts: 575Member
    it1991 said:


    someone thought it would work... I reached out to the guy who did it and said he did a heat-loss analysis and that the right amount was put in... oh well. too late to question it now.

    All heat loss analyses are not created equal. If you want to DIY some of this project the heat loss analysis is a great way to do it.
    Its worth doing just to see how good the original analysis really was. If you are good with simple math and a tape measure, you can do it. It can be done with paper and a calculator, but if you can use a spreadsheet, it's even quicker. You can also use one of the free available on line heat loss programs.
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread: http://forum.heatinghelp.com/discussion/154385
    System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg
  • hot_rodhot_rod Posts: 11,259Member
    If you take the steps and determine that rooms do not have adequate fin tube, those sections with just pex could easily have fin tube installed. if the enclosure is in place you can even but the bare fin section to install, crimp it into the pex.

    In reality with the boiler you have you would like to be over-radiated to use the lowest possible supply temperature and maximize the boilers efficiency.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • it1991it1991 Posts: 4Member
    hot_rod said:

    If you take the steps and determine that rooms do not have adequate fin tube, those sections with just pex could easily have fin tube installed. if the enclosure is in place you can even but the bare fin section to install, crimp it into the pex.

    Would i just use the same fins as for copper? could you send me an example if you get a chance.

    I will try to do the analysis myself.

    Some more info. the whole first floor is a loop. So the pex is used simply as a supply to the copper baseboard however it is covered with the baseboard to make it look like the whole room is generating heat.
  • Jamie HallJamie Hall Posts: 10,284Member
    "Would i just use the same fins as for copper? could you send me an example if you get a chance. " -- no. What @hot_rod meant was to take out a section of the PEX and install a section of copper pipe fin tube in its place, using crimp fittings at the ends.
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • GordyGordy Posts: 9,264Member
    Slant fin sells bare fine tube elements in various lengths.


  • hot_rodhot_rod Posts: 11,259Member
    lots of bare fun tube on Ebay for some reason
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • it1991it1991 Posts: 4Member
    Got it. I misunderstood.
    I'll probably have to get a plumber for that as I have no experience outside of what I've read
  • sallaberrysallaberry Posts: 7Member
    You need about 25 btus per square foot baseboard at 180 is about 500 btus per foot.
  • LanceLance Posts: 122Member
    Try the UltraFin system I have used it quite successfully. When used below floor, not in contact with floor, can use higher water temps. http://www.ultra-fin.com/
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