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Do you use floor sensors in radiant system in all rooms or just bathroom?

Joseph_4 Member Posts: 230
Hello out there, I am working on a house with radiant heating.. was curious where i should install floor slab sensors. I was told by a design company that usually you'd use them in a bathroom but not really in a living room. there would rely on air temp. What do you do?


  • STEVEusaPA
    STEVEusaPA Member Posts: 5,318
    edited June 2019
    Depends on the type of radiant. If I needed to, I’d only use a floor sensor in high mass slabs.
  • GroundUp
    GroundUp Member Posts: 1,283
    Depends whether a comfortable floor or air temp is more desired. I will sometimes use both in buildings that have a lot of people coming and going, like offices for example. Depending on finished flooring, I'll use them in houses too. Exposed concrete, and tile no matter the room will sometimes be uncomfortable to walk on when running on air temp alone, especially if there is a lot of glass/solar gain. Can't really answer the question without knowing some more details, other than it doesn't hurt to bury a sleeve so you can drop in a floor sensor later if you want. Tekmar 519 will run one or the other or both and has been my go-to
  • Joseph_4
    Joseph_4 Member Posts: 230
    thank you!
  • Dave H_2
    Dave H_2 Member Posts: 480
    I try to stay away from them, in the past they have been too confusing to a homeowner; then the rooms get huge temp swings, what setting can I change......
    I would rather modulate the water temp serving those rooms on outdoor reset.

    Dave H.
    Dave H
    STEVEusaPAJean-David Beyer
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,307
    I've had very good results with a good outdoor reset curve and a good digital thermostat set on 1 CPH. I like to get the reset curve to achieve about 70% run time on a windy day. Call it near constant circulation. This gives good margins for open doors and slightly faster recovery from a setback (even though I never recommend a setback with high mass radiant).

    I have many systems out there with this control strategy, including my own heated slab home. Even our direct piped mod/con radiant slab shop is this way with two 12x12 overhead doors and temperature settings work very well. When its -20F it works well too, loads of condensation out of the boiler with almost no visible exhaust from boiler.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    Jean-David Beyer
  • hot_rod
    hot_rod Member Posts: 15,048
    There are some applications where floor sensors have some value. A large tile floor bath for example. When the home is in cooling mode, you can set a floor temperature not to exceed, say 80 F or so. They keeps the tile from being shockingly cold on bare feet.

    Keeping in mind that you are heating and cooling $$ at the same time as you want FA registers in the master to help with humidity control.

    I think the ideal control involves indoor air temperature sensing along with outdoor and indoor. Adding predictive outdoor function is another option, watching incoming weather conditions and ramping accordingly. Some would suggest air temp and indoor reset are ideal with modulating heat sources.

    IAQ is a bigger puzzle, as humidity, air quality, and ACH control is also part of the bigger picture

    The goal really is to keep the occupants comfortable inside the building. How much technology you want or need to accomplish that varies depending on the installer and owners technology limits :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 15,048
    BroEliz16 said:

    Is it necessary to use sensors in bathroom?
    How to choose the best sensor brand for my bathroom?

    Not necessary, the floor sensor merely gives you another level of control for the system.
    Many of the electric cable and mat systems use floor and air sensing control to provide floor warming function, in addition to room heating. tekmar, Uponor, Ecobee, Honeywell are a few brands that have sensor options.
    The electric systems manufacturers have some real nice control stats, with sensors but are generally 120 or 240V.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream