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Radiant heating and cooling system in concrete slab 1950's house. Salvageable?

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KillerBootsMan
KillerBootsMan Member Posts: 5
in Radiant Heating

Trying to figure out if I can get an old radiant and heating system working again, but have no idea if it's possible. Please help!

I bought an old house built in 1952 that apparently has a radiant heating and cooling system built into the concrete slab floor that sits on the ground (no crawl space), and the concrete slab second floor. The second floor slab was the roof at the time, but it was built onto in the 80's and there are now rooms above the second floor slab.

I found the blueprints (link below) and it looks like there were copper pipes and concrete ducts built into the first floor slab. To cool, there was a cooling tower used to pump water through the lower slab and through the upper slab...as far as I can tell.

I tracked down the HVAC contractor who has been servicing this house for the last 60 years. He said "there is no radiant heating in the floors" (although the blueprints suggest otherwise). He thinks the architect owner may have installed the copper tubing in the floors, but never used most of them. The owner told him to switch to a boiler system (??) and the only pipes they used in the slab were the ones that went straight to the boiler to force air through the ducts.

He said that that if the copper radiant floor heating tubes were installed, they were never used. He's really old and was having memory issues though. He suggested to scrap the whole system and use minisplits in every room. I'd rather preserve, repair and use the old system (plus new AC for the second floor) if at all possible.

Any idea whether it's possible to use the old system to heat and cool? Can anyone glean anything from these blueprints? Any suggestions on where to start?

Thanks in advance for your help.

https://acrobat.adobe.com/link/track?uri=urn:aaid:scds:US:e36d8676-7566-3bbe-a01b-ac802de4b8d0

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,117
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    The first thing you need to do is test the piping with air pressure at about 15 to 30 PSI. If there are no leaks, then you might be able to use the floor piping for heating. I don't recommend using a cold floor for the purpose of air conditioning. It just seems that a cold floor will attract condensation and constantly have mold and mildew as a result.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    HomerJSmithbburdKillerBootsManMad Dog_2
  • hot_rod
    hot_rod Member Posts: 22,263
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    looks like at least two manifold locations, have you found them?

    copper in concrete can deteriorate from the ground it sits on or the ingredients in the mix

    You could spend a lot of $$ and have tube fail in a few years. Is it worth a gamble?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    EdTheHeaterManGGrossMad Dog_2
  • KillerBootsMan
    KillerBootsMan Member Posts: 5
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    hot_rod said:

    looks like at least two manifold locations, have you found them?

    copper in concrete can deteriorate from the ground it sits on or the ingredients in the mix

    You could spend a lot of $$ and have tube fail in a few years. Is it worth a gamble?

    I found one manifold location in the middle of the house in a little control closet (pictured below highlighted in yellow).



    It has a mess of wires and an old control board with switches that just say "Winter," "Summer" and "Off." There's a hot water heater in there, with two others in different closets. There's also a custom built heat pump outside that runs pipe into the house.

    I did find a couple closed off ends of thick copper tubing in the control closet next to some big valves. Looks like the ends of the closed off system that was never used. The copper looked like it was in great condition, but I have no idea whether it works, what condition it's in or whether it's worth the gamble.

    Gas is super expensive down here...$250 last January for my current 1,900 sq. foot house...so I'd love a radiant heat system (if it works). Everything the owner put in is commercial grade, so I'm hoping for the best.

    I will ask the HVAC guys to do the pressure test as EdTheHeaterMan suggested.

    Thanks guys. Any other comments, recommendations or suggestions are more than welcome!
    Mad Dog_2
  • pecmsg
    pecmsg Member Posts: 4,893
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    Copper in concrete for 70 years highly doubtful it’s tight but you dont know. Pressurize and find out. 
    KillerBootsManMad Dog_2
  • hot_rod
    hot_rod Member Posts: 22,263
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    I'd be surprised if there is any or much insulation under or around the slab? So it could be an expensive heat.

    A pressure test will tell if it is currently ok. Hard to say with copper tube in or below the slab. A pressure test may be an inexpensive first step.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • jumper
    jumper Member Posts: 2,289
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    Forget about it. Bite the bullet and install modern tubing in walls for ceiling height panels. Evaporatively cooled panels will not sweat. Use a closed circuit cooler instead of an open cooling tower. I presume you live somewhere that often enjoys a substantial wet bulb depression?
  • KillerBootsMan
    KillerBootsMan Member Posts: 5
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    hot_rod said:

    I'd be surprised if there is any or much insulation under or around the slab? So it could be an expensive heat.

    Here's what I found as far as insulation under the slab:



    Not sure what "Zonolite" waterproofing is.
    reggi
  • KillerBootsMan
    KillerBootsMan Member Posts: 5
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    Some more..


  • bburd
    bburd Member Posts: 923
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    If I am reading the drawing correctly, the Zonolite is insulation. The waterproofing is a membrane between the insulation and the concrete slab above.
    —
    Bburd
    KillerBootsMan
  • KillerBootsMan
    KillerBootsMan Member Posts: 5
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    jumper said:

    Forget about it. Bite the bullet and install modern tubing in walls for ceiling height panels. Evaporatively cooled panels will not sweat. Use a closed circuit cooler instead of an open cooling tower. I presume you live somewhere that often enjoys a substantial wet bulb depression?

    I live in the south where it gets really hot. The second floor is supported by steel I-beams spaced two feet apart. The current ceiling on first floor hangs below those I beams. See pic below.

    Are you talking about running tubing in the ceiling and hanging cooled ceiling panels under these beams?


  • jumper
    jumper Member Posts: 2,289
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    Radiant evaporative cooling doesn't work in humid climates.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,117
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    Levittown was built with radiant heat using copper tubing in a concrete slab around that same time. No insulation under the slab and the least costly materials were used. I would say that well over 90% of those copper radiant floor systems are abandoned today. They started to abandon them as early as 1970s and 80s

    You have something similar but different. The fact that the person that specified the tubing and other components was an engineer or architect and was planning on using the home himself, makes me think that you have a better than 50% chance that the system may be usable. Better materials and that waterproofing layer can only help. If I were in your shoes, I might give it a go. At least you might get 5 or 10 years of good service... Maybe longer. I would strongly recommend that you install a water meter on the inlet of the boiler feed water. This way you can monitor the system and will notice a leak very quickly. You won't need to see the fuel bill go up substantially to detect the water leak.

    Best of luck!

    Mr.Ed

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Mad Dog_2KillerBootsMan
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,110
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    Whats the harm trying? Forget the cooling aspect...try to get that radiant slab resurrected.  I you plan on a Hot water hydronic system anyway, pipe out a boiler and give it a try...If it doesn't work, or leaks, THEN you're gonna spend some money.  As the guys said, test with air first.  The Levitt houses that ARE still operational are pushing 80 yrs now...I'd give it a shot.  Mad Dog 🐕   keep us posted  
    Consulting by Mad Dog & Matt Jr.
    KillerBootsMan
  • IanCampbell
    IanCampbell Member Posts: 1
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    jumper said:

    Radiant evaporative cooling doesn't work in humid climates.

    what its work in 40 degrees??
  • pecmsg
    pecmsg Member Posts: 4,893
    edited May 2023
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    jumper said:
    Radiant evaporative cooling doesn't work in humid climates.
    Yes it does. 
    The  Dew point has to be controlled 1st. 
    Canuckermattmia2
  • hot_rod
    hot_rod Member Posts: 22,263
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    here is an option for a fill tank to prevent flowing water if there is a leak in the slab.
    Fairly inexpensive to build.
    A wash machine hose to connect to the boiler drain.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Canadian_Al
  • mattmia2
    mattmia2 Member Posts: 9,749
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    Zonolite is a trade name for vermiculite. Looking at that section it looks like there is just a token amount, not enough to provide much insulation.
  • jumper
    jumper Member Posts: 2,289
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    pecmsg said:


    jumper said:

    Radiant evaporative cooling doesn't work in humid climates.

    Yes it does. 
    The  Dew point has to be controlled 1st. 


    How do we control outdoor dew point or wet bulb temperature?
  • mattmia2
    mattmia2 Member Posts: 9,749
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    Dehumidification.
    pecmsg
  • pecmsg
    pecmsg Member Posts: 4,893
    edited May 2023
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    jumper said:

    pecmsg said:


    jumper said:

    Radiant evaporative cooling doesn't work in humid climates.

    Yes it does. 
    The  Dew point has to be controlled 1st. 
    How do we control outdoor dew point or wet bulb temperature?

    You dont control outdoor RH
    You change the Dew Point
    Dehumidifiers
    Chilled water coils

    There are several ways of doing it.

    Plenty of building have evaporative cooling!

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