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Frost Heave Prevention w/ Small Hydronic system

barney15 Member Posts: 1
I am attempting to keep a building slab above freezing. The BTU/h requirement for the entire 1500sqft is only about 4500 BTU/h.

As you can imagine, the standard radiant set-ups are way over sized. I am also trying to avoid electric water heaters if possible (prefer natural gas/propane).

I can't find a small gas unit that would make sense, is the 1-2KW electric boiler the best option for this, or is there another way? The system will utilize 60/40 water/pg in case it is shut off.


  • ScottSecor
    ScottSecor Member Posts: 863
    In your case, maybe a strip of electric baseboard heat may be the best solution.
  • GGross
    GGross Member Posts: 1,072
    Without knowing the exact application, if your load is only 4,500 btu I would use a 2kw mini-boiler from electro. For gas you could limit your output on a wall hung modulating boiler. I know I can do this on the new Viessmann boilers to limit their max output right down to it's minimum input, which is 2.5kw on the smallest model. I am unsure but you may find a smaller boiler that has a lower minimum output, that would also allow you to limit the max output.
    Paul Pollets
  • Paul Pollets
    Paul Pollets Member Posts: 3,657
    Most slabs take at least 10BTu's/PSF depending on slab insulation thickness and building envelope. 3 BTu's seems way too low. I'd install the smallest Vitodens, as GGross suggested.