Good morning and happy 2020 ladies and gentlemen! Hope everybody is doing well.
So, I'm looking for opinions on a radiant garage ceiling that's a little "out of the box". Last fall I built a 32x48x10 garage on a radiant slab. The structure itself, walls and ceiling, is actually a mishmash of foam rail walk-in freezer panels made entirely of high density foam, no wood whatsoever. There are structural wood trusses on top of the ceiling that sit on the side walls and actually support the foam ceiling panels using brackets from the freezer MFG. It's a pretty cool setup, R40 foam with zero thermal bridging anywhere but the door and window frames. This is going to be primarily my toybox to keep ATVs, snowmobiles, motorcycles, etc climate controlled but I am also going to move my business items out there to clear some room in my shop and will be doing my prefab and organization out there from now on. I run an outdoor wood boiler that heats my house, shop, and now this building via insulated underground lines which I have set up to run through a plate HX on the OWB to keep the atmospheric system separate from the loads, which allows glycol in the loads to avoid the imminent 24/7 circulation that comes with an OWB. Everything sits idle between heat calls and only circulates underground during a call for heat, with individual load circs in each building. At this point in time, I have only a cabinet unit heater in the new freezer garage just temp'd in with pex until I figure out what I want to do with the radiant. The plan is to set up the system with a mixing valve for the radiant floor (primary heat, just keeping it at 45 degrees), but a bypass around the mixer if I want to use the CUH or radiant ceiling for quick heat up, using the same circ.
The ceiling finish in this garage is currently just the 30ga galvalume skin of the freezer panel and I would like to run a high temp radiant ceiling directly on that surface with no additional covering. I am leaning toward a Thermofin C or Joist-Trak system with the flat side up against the galvalume. Being high temp, I feel PAP or FostaPex would be most appropriate to reduce thermal expansion and noise while maximizing output. This radiant portion would only be about a 6x40 ft strip above the work area along one wall. Running 160-170 degree SWT, using the exposed plates, ought to give me enough of a surface temp to create 70+ BTU/ sq ft of emitter if my research is correct. I'm a radiant slab guy so the walls and ceilings are a bit foreign to me as are the transfer plates in general, so any information and input would be greatly appreciated. With the system I have planned, I will have the slab, ceiling, and CUH all on separate zones controlled by a single thermostat and circ using manually actuated valves with the ability to run the ceiling and CUH in series if I choose to, running a high delta setup at 4 GPM with 160-170* SWT depending on the OWB cycle (10 degree differential). Design heat loss is 17,000 BTU at -30F outside and 60F inside, but the slab will maintain a 45* ambient temp at all times. The ceiling will only be used for quick heat up to 60-65.
Sorry for the rambling, I just don't want to leave out any details. Thoughts?