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Commercial infloor

I'm installing a new commercial boiler in a building with infloor heat only. It's a large industrial warehouse. Maybe 30 to 40,000sq ft. 
The only boiler control was from 50 years ago and I recently found an outdoor temp sensor going through what used to be an outside wall into a new addition. So clearly it wasn't doing anything and the guys were complaining it was too hot. 

My question is whether or not I need outdoor reset in this application. 
I can install the sensor but I was wondering if I could control infloor temp in another matter. 
I was thinking of simply setting the boiler temp to a certain temperature so the Warehouse is getting the same water temp all the time. But I'm on the prairies and it's gets very cold. 
Just looking for some good options to maintain good temp during winter. 


  • Ironman
    Ironman Member Posts: 7,119
    The supply water temperature to the floor needs to be controlled by outdoor reset or the floor will continue to overheat. It’s called the flywheel effect. The mass of the slab will continue to give off heat for hours after the thermostat is satisfied.

    Any new mod/con boiler has ODR built into it. All you have to do is install the outdoor sensor and set the ODR curve properly.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    EBEBRATT-Ed Member Posts: 13,450
    well you need some type of control. With radiant heat you need an indoor space temperature and an outdoor temp sensor. Look at Tekmar Controls.

    The outdoor sensor should be on the North side of the building in the shade.

    Depending on the boiler you use (cast iron or mod con) you may need a mixing valve and other controls to maintain the water temperature
  • Zman
    Zman Member Posts: 7,447
    More details or pictures would help. You cannot just turn down the temp on a conventional boiler, it will condense and destroy itself from the inside out.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Paul Pollets
    Paul Pollets Member Posts: 3,620
    I'd be using the Viessmann CU3 model. It doesn't require a mixing valve or motor, comes with a sophisticated OR control and computer, can be piped direct and fully condenses. You'd need a low loss header for supply distribution.
  • metrosilo
    metrosilo Member Posts: 29
    Using a Paterson Kelly Mach C1050. It's fully modulation and a condensing boiler. I'm installing the outside reset. I was just wondering if there was different options for control. 
  • Zman
    Zman Member Posts: 7,447
    Outdoor reset controlled by the boiler is the way to go. You will want to pipe that boiler primary secondary per the I&O manual.

    You can probably run at 120 degrees+/- on the coldest day.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Mike_Breault
    Mike_Breault Member Posts: 36
    Mike from tekmar here, if running the wire is an issue for OAT sensor, look athe tekmar 087. https://www.watts.com/products/hvac-hot-water-solutions/controls/control-accessories/087/087

    configurable to match 5 different types of thermisters

    Good luck!