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1950 Radiant Slab

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Phillip
Phillip Member Posts: 4
Good morning. Seeking advice with concrete radiant slab. Building is a Bucks County PA. barn that was converted to a seven unit apartment building shortly after WWII. Originally, building was all radiant heat. Two ground floor units are SOG with steel pipe radiant heat cast in concrete. One unit's pipes failed 30 plus years ago. The five units on the framed levels have steel pipe radiant ceilings cast in wire lathe and plaster ceilings. One of these units failed 30 plus years ago. Convection baseboard heat was installed in both units with failed pipes. Ground floor unit with working radiant heat is now vacant. Pipes are on borrowed time. Would like to upgrade unit with another type of radiant system. Considering a radiant panel system installed on existing slab to avoid a cold floor. Exterior walls are approximately 18" thick field stone walls with wood framed walls on the interior side. Suggestions and guidance would be greatly appreciated:

1. What brand of engineered radiant flooring is fit for applying direct to existing slab( Warm Board, etc.)
2. Do these products need any additional thermal break from existing slab.
3. Is radiant ceiling an option with out having cold feet. Would like to avoid carpet.
Again, any and all guidance would be greatly appreciate.

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  • Gordy
    Gordy Member Posts: 9,546
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    Look at Roth panels it has the insulation in the panel.

    http://www.roth-usa.com/products_radiant_panelsystem.cfm

    I highly doubt the slab was insulated. Probably sand fill.

    Radiant ceilings are great, but they won’t warm the floors like a radiant floor.
  • Phillip
    Phillip Member Posts: 4
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    Thanks for the reply Gordy. Also, can anyone recommend a good gas boiler professional experienced with this type of system. Building is located in Milford Twp. PA. West side of Quakertown PA. No one close listed on Heating Help.
  • Gordy
    Gordy Member Posts: 9,546
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    There is certainly other methods of insulating slab, and doing an over the top panel. The key is what you can stand to lose for head room, and what can be done with the existing mill work to accommodate the build up.
  • Phillip
    Phillip Member Posts: 4
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    Gordy,
    Although not mentioned previously, build up height is an issue. the Roth panel would work at 1" thick.
  • Gordy
    Gordy Member Posts: 9,546
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    Usually it is unless a total renovation is done.

    You really can’t beat an all in one system for the build up height of one inch plus floor finish.

    Roth also allows different tube spacing. Where warm board is 12”.

  • mikeg2015
    mikeg2015 Member Posts: 1,194
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    IF you can handle the added height add at least 3/4” XPS. I believe it come in tongue and groove with a skin and will also act as a partial vapor barrier for laminate or wood floors. you will need to give up about 2-1/2 of height depending on floor system used.

    For a boiler, you can go wit ha regular wall mount or a combi if you want to combine it with Domestic Hot water. We sell Naviens and have had great results. Just did a garage floor with radiant heat and DHW. They can do long distances on 2 or 3” PVC so lots of flexibility.
  • Gordy
    Gordy Member Posts: 9,546
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    In these situations where the old floor radiant managed the load, I think any over the top detail that includes some insulation is better than the previous tubes in the slab.

    One being r 1 is 100% better than r 0.
    Two an over the top system with some sort of insulation detail is not going to be in the concrete to absorb the btus produced. It will actually respond faster, and have less fly wheel than the old slab.

    So no matter what it’s a step up to put the radiant panel on top of the existing slab. Which should also see some reduced operating costs.
  • Gordy
    Gordy Member Posts: 9,546
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    We would all like to see more insulation under the panel. Sometimes it’s just not cost effective.
  • Phillip
    Phillip Member Posts: 4
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    Thanks again Gordy. I agree 100 percent. No insulation under that old slab. Will look into Roth panel.
  • Gordy
    Gordy Member Posts: 9,546
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    what I like about the Roth is the foam contacting the floor instead of wood.
  • Paul Pollets
    Paul Pollets Member Posts: 3,658
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    Our codes in WA state call for R10 on top of existing old slab when adding a radiant panel