Radiant floor heat retrofit

ED 3000 Posted By ED 3000, Nov 6, 2018 at 12:31 PM

  1. ED 3000

    ED 3000
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    Dec 23, 2015
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    Removing the big radiators out of my small rooms would be a huge improvement. Also, I'm thinking a huge improvement in comfort.

    Looking for good resources to use to plan a hot water based in-floor retrofit.

    I'll be going in through the bottom, easy access under the wood floors in the cellar.
     
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  2. festerw

    festerw
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    Nov 16, 2009
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    I did a retrofit a couple years ago in my house. If you have enough room do two runs of tubing in each joist bay, I only did one and you can definitely tell "hot spots" on the floor. I think the heat would dissipate better with two runs but I also have true 3/4" floor boards so that may be part of the issue.

    Using a thermal barrier on the bottom of the joists makes a huge difference, I saw a 2 degree temperature rise with 25 degree outside temps with no other changes.

    I'm using an old hot water tank as the heat source, 3/4 pipe to the manifold, 1/2 oxygen barrier pex. 3 zones with cheap Honeywell thermostats, Taco 007 circulators, and Taco SR503 switching relay.

    I'm sure there are better ways to do it but this works pretty well down to single digit temps.
     
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  3. ED 3000

    ED 3000
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    What did you use as the thermal barrier at the bottom of the joists?
     
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  4. EatenByLimestone

    EatenByLimestone
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    Have you considered dropping the water temp in your big radiators? It makes a huge difference in comfort.
     
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  5. ED 3000

    ED 3000
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    No comprende. They work hard to provide any heat as is.
     
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  6. festerw

    festerw
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    ED 3000 likes this.
  7. ED 3000

    ED 3000
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  8. festerw

    festerw
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    It's kind of like foil, but much heavier and it has nylon reinforcements running through it.

    I looked at the foil backed foam but it was way more expensive and unnecessary for my basement since it's useable space
     
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  9. ED 3000

    ED 3000
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    Makes sense. Thanks!
     
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  10. peakbagger

    peakbagger
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    Jul 11, 2008
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    FYI, do a bit of research before jumping in on this. If you have a "thick" flooring system the response of the system is going to be limited. If you have conventional wood flooring that is another consideration. The problem is that the floor system acts like insulation so the heat tends to flow into the space under the floor. That is why using radiant shields and insulation under the tubing is important but ultimately the thicker the floor the higher temp water you will need to run. Definitely avoid rugs or carpeting.

    Once you go radiant in the floor, its set the thermostat and leave it there, no set back as the response of the system is quite slow. It works well in tight homes with tight windows but is less successful if you have a lot of heat loss in the wall and window system. Generally radiators are placed under windows as that is where the heat loss is and if they arent there you may start noticing drafts and cold spots near the windows. I have seen several references to folks having to install insulated blinds on their windows when they switched to radiant floor heating due to the combination of high infiltration and the cold windows causing it to be uncomfortable when sitting near the windows.
     
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  11. zrock

    zrock
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    Have you thought about upgrading your old rads to the newer more efficient and smaller rads?
     
  12. CaptSpiff

    CaptSpiff
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    Examples??
     
  13. zrock

    zrock
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    Google is your friend... you can get them similar to electric baseboards, slimline, wall mount, and everything in between

    Sent from my SM-G903W using Tapatalk
     
  14. EatenByLimestone

    EatenByLimestone
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    A house needs a certain number of btus to stay at a certain temperature.

    Many systems have the water temperature set at around 180-190F. They deliver this heat in short bursts.

    The boiler turns on, blasts out heat, then turns off. You get an on/off effect that really isn't steady. Your body feels this.

    Lower water temperature can deliver that heat with longer cycles at lower temperatures. It's what radiant heating systems do. Only its using the system you already have. The fewer on/off cycles give a more steady heat and the cycles are easier on the equipment.
     
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  15. ED 3000

    ED 3000
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    Got it, thanks! I'll check it out, and see how it works.

    Now I guess I'll have to figure out how to check the temp and adjust it.
     
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  16. EatenByLimestone

    EatenByLimestone
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    On older boilers there's an aqua stat. On newer boilers you have to adjust the computer program.
     
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  17. ED 3000

    ED 3000
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    IMG_20181108_180721988.jpg

    Do you think there's a digital computer adjustment in there?

    I'm guessing it's the grey box. No adjustment on the outside, so I'll have to take the screw out to peek inside.

    Analog, with a few miles on it, just the way I like it.
     
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  18. EatenByLimestone

    EatenByLimestone
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    Lol. Probably not too much in the way of a computer there.
     
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  19. jeanw

    jeanw
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    is that stuff same thing as "double bubble" Hubby called it?was used. under the metal roof. I don't call it double bubble I call it single bubble. I bought some real "Reflective "alum barrier with aluminum with bubbles on both sides. Bought it at a big old hdwe store years ago to wrap water heater etc.s. Still some of both left. just a saying and asking. Thanks y'all.
    Oh we were supposed to do thermal radiant floor under the floor beneath the joist.
    even bought the outside propane unit. Unfortunately Hubby gave away the "Lifetime " nice water htr.it would have held the water. as a storage tank for the Propane unit
    It has never been used yet Just hanging on the outside of this place.. At least it's not in the sun prob full of wasp and spiders . also got lots of books on the subject too...
     

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