Radiant Floors and Basement Condensation
Hi all, first post here. I know ‘radiant cooling’ is a thing, and that it can create lots of humidity as well. I’m looking for a ‘middle ground’ solution
I own a custom built home with hydronic radiant on the first floor and basement, I have a Fujitsu Halcyon mini split for a/c and auxiliary heat though I rarely use it. Vast majority of the house is concrete slab and cinder block walls, its built similar to the Bachman-Wilson home that FLWright designed. I have about 2200ft of PEX running throughout the home and detatched workshop, most of it 3/4″ and set within the slab. All heat loops are tied to a pair of Embassay manifolds to create a basic closed loop system. This is run through a condensing boiler (cheap Navien unit) with one of those bypass/mixing manifolds right below it (seems water flow can bypass the boiler?).
The issue I have is with basement humidity. There are no windows in my basement, it is 100% below grade and surrounded by the first floor slab, the stairways are open however and air is free to flow up to the first and second floors through the two open staircases. Regardless, even on a mild day the humidity down there sits at 70-80% without a dehumidifier running. On warm summer days this causes the plumbing to sweat (well pump tank and filtration is down there). In contrast I have a large great room with vaulted ceilings, the slab sits on grade and there are 40+ windows in this room, many of which are south facing and let in tons of light. This makes the slab pretty warm on that side of the house, and this space alone has three radiant loops within it. The far side of the house stays very cool, as does the workshop.
So in my mind there is a solution… Swap warm water from the great room slab with cold water in the basement/ workshop slab, in theory reducing humidity downstairs and potentially raising it upstairs (which is not an issue). Can this be done efficiently? Perhaps I can simply run the circulator pump next to the manifold and let everything mix to an even temperature. The workshop slab stays chilly even in the summer (below grade, no windows), and the two workshop loops (300ft ea) run underground between the structures, these two lines alone could act as a form of heat pump in my mind. I know there are many variables and I can provide much more info if it’s helpful, but I dont want to overload my original post. Let me know what you guys think. Thanks.
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