Garage radiant ceiling

GroundUp

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?

Zman

A structure like that will take very little to heat. I am sure you could do it with just the slab or ceiling (at much lower water temps).

A buddy of mine did a garage similar to yours and had to add an HRV because the shop overheated when he pulled vehicles in. He also needed ventilation to get rid of the moisture coming from melting snow off vehicles.

As much as I think the radiant ceiling would be awesome, I think idling the slab around 60-65 degrees (slab not air temp) and using a fan coil and HRV to bring up temp and provide ventilation would be more functional. The HRV and fan coil could be controlled by both occupied temp and indoor air humidity.

Gordy

I see where you are going with this for quick heating.

I’m not going to say it wouldn’t work, but you may be better off going with fan coil unit heaters for that quick burst. Much more cost effective, and less worry about possibly damaging exposed tubing. Plus you get some air movement.

Saves the cost of plates, tubing,manifolds, and a mixing valve. Plus labor.

GroundUp

Thanks guys, but the heating method is not up for discussion unless it's a variation of radiation in my work area only. As I mentioned, there is already a CUH in place and it will stay there if I wish to heat the whole building quickly. I could easily keep the building at 80 degrees with half the loops in the slab, but I don't want to- the slab will keep it around 45 and that's that. I need response time. What I want, is a form of radiation that only covers my ~200 sq ft work area instead of heating 17,000 cubic feet of air. The moisture thing has already been taken care of with a dehumidifier, I have no interest in an HRV as I tried that in my shop and it's a PITA. I do not have a ton of experience with radiant ceilings, especially high temp like I am thinking, but if you've ever stood under a radiant tube heater you know what I am looking for.

Gordy

Is the skin of the insulated panel smooth?

GroundUp

Gordy said:

Is the skin of the insulated panel smooth?

Not smooth, per se. It's got a texture comparable to linoleum flooring, off the top of my noggin. I can get a picture when I get back out there, just got home from Mexico this morning and had a foot of snow to plow along with several other items to take care of today.

GroundUp

I have done a number of lay-in type radiant ceiling panels that drop into 2x2 or 2x4 grid, which are typically full temp. That is what I'm after, but without buying 40 panels like that.

Zman

The radiant ceiling will work great for rapid radiant heat. It can be done using strips of plywood to support either omega plates or inverted radiant panels. Drywall would go on over the top.

Gordy

@hot_rod did a small scale radiant ceiling with plate, and tube exposed. I’m sure he has a pic. I thought it looked kind of cool.

I’d be curious of what an infrared would show with the galvanized skin absorbing the heat from the directly attached aluminum plate. Especially with high supply temps.

That’s why I asked if it was textured, or corrugated. Sounds like mild texture.

Zman

Exposed would be cool. You could just screw joist tracks to the ceiling and let it be art.

GroundUp

Right, exposed was my method of choice. I thought it would look pretty cool with ThermoFin C or Joist Trak with bare PAP loops at the ends. This building is not photogenic structure by any means, the panels were used and have dents, holes, and butyl smears everywhere so it'll never be a showpiece but I'd prefer something a little more aesthetically pleasing than omega plates with tubing on top or inverted with 1x6 above. Lightweight would be great also, I don't want any more weight than necessary hanging from screws in the galvalume since there's no wood to screw to. As for the skin on the panels, there is 5" of foam on top of the skin so I don't foresee much absorption into places I don't want it, but if the plates are tight together for tight tube spacing a little spread into the aluminum skin should be a good thing, I'd assume. Probably wouldn't go so far as to add thermal paste or anything, but a little transfer wouldn't hurt.

Zman

I think for the WOW factor these would be my choice.
https://www.rehau.com/us-en/mechanical-and-plumbing/radiant-heating-and-cooling/hydronic-radiant-heating/below-floor-plates#tab2

hot_rod

I did exactly that in a hot rod body shop years ago. I used the C shape ThermoFin, screwed to the Galvalum ceiling with zip screws. Then snapped copper tube into it. I used my Curvo to make then loop ends.

Around here they flip the metal panels for ceilings and walls, you probably do also. So no ridges to work around or over when you mount stuff to them.

The metal roofing manufacturers will do a reverse stamp if you ask, so the glossy side is on the reverse, if you use colored panels.

Basically you would have a nice noise and dust free, quick accelerating, non stratification 1536 square foot panel radiator. With that much surface area you might heat with 80° SWT !

I would so do that in my shop since I like unusual approaches to hydronics.

I have pic on floppy discs somewhere, I'll look if you are interested. It sounds like we have the exact same idea.

STEVEusaPA

Zman said:

I think for the WOW factor these would be my choice...

Those look Interesting. Much easier install, and looks like it would be easier on the deltoids. Although it looks like less overall contact to the subfloor over 2 plates.
Any experience with them Z?

Zman

STEVEusaPA said:

Zman said:

I think for the WOW factor these would be my choice...

Those look Interesting. Much easier install, and looks like it would be easier on the deltoids. Although it looks like less overall contact to the subfloor over 2 plates.
Any experience with them Z?

I have not used them yet. Rahau is a good company and the specs look great.

Gordy

Just thinking out loud. On an totally exposed detail like that, I’m wondering if an extruded plate would have more, or less benefit. Thinking more mass of an extruded would take a bit longer to get up to temp than heavy gauge plate, but hold heat a bit longer. Heavy gauge would be a bit faster response. Probably a wash, except for cost.

GroundUp

See, I considered that Rauplate briefly but had this thought that the C channel would be more productive. Maybe I'm nuts? Cost is honestly not a monstrous factor, I'm open to suggestions there but I will not be spending Warmboard dollars or similar- both for cost and weight. Sounds like this is up for debate; I am open to the idea of mix-n-match and would be happy to report the FLIR findings of the output later, if y'all would like. This is more of an experiment than anything and will be a place I can show potential customers after I see how it performs, as a potential sales point. Maybe 1/2 Rauplate and 1/2 Thermofin C? Half of each with pex and half with FostaPex? I'm open to splitting it up into 4 loops for research purposes if nobody has done it yet

Gordy

I’d do just like @hot_rod did for the body shop project.

Well I’m sure copper tubing was cheaper back then definitely superior though.

Be interesting to see how the plates chosen transfer to the galvanized skin of those insulated panels. Maybe just use different style plates. Thermofin C, rauplate like @Zman posted,

GroundUp

@hot_rod I'd be very interested to see photos of that body shop if you are able to locate them! I'm definitely too fat and lazy for copper tubing in here but it would sure look awesome. Really leaning toward FostaPex since the aluminum is on the exterior and the color is less eccentric than say, red for PAP. And I prefer crimp fittings over compression anyway.

hot_rod

I doubt you will force FostaPex in extruded plates, not easily. Probably fit into the thin flashing gauge plates, maybe those Rehau that Carl showed.

Still searching for those pics, here is how i did the copper for it. But in C fins. I may run down to that shop today, get some feed back after 15 years of operation!

GroundUp

Thanks Bob, looks like you have some Fosta there on a C fin. I was doing some reading and had seen others saying they were able to pop PAP into both ThermoFin C and Joist Trak with some convincing, is that a stretch?

Larry Weingarten

Hi, For what it's worth, I did radiant walls in my house and used roll formed copper tube and fin made for solar collectors. It was made by North Star Company in Gardens CA https://www.northstarcompany.com/ . I figured if heat could move from the fins to water in the tube, it could move just as well the other way. They can make it in whatever length you want.

Yours, Larry

hot_rod

FostaPex is a larger OD than PAP. I measure right at .703, regular pex and PAP is 5/8, .625.

Most PAP is CTS "copper tube size". There was some large OD metric sized stuff around but the name brands are all CTS, probably 80% of the PAP is relabeled Reifling, 5/8" od just like 1/2 copper tube..

The Fostapex has the aluminum and PE layer over the pex inner tube which is what the OD grows. They take a 5/8" OD tube and add the additional layers. that is why you have to strip the out layer first to put the crimp collars on. So is is too large for the extruded plates and may stretch that channel too much.

I doubt you could push it in by hand.

Here is what it looks like after I put a piece in the vice. It actually "egg shapes" the FostaPex and distorts the ThermoFin channel also.
You would want a pneumatic palm nailer with a rubber tip to put the tube in. Radiant Design used to sell the plastic palm nailer tip. Very noisy tool, wear ear plugs.

I would use a CTS sized PAP, not FostaPex in extruded plates.

GroundUp

Dang, you are absolutely correct Bob! (you knew that) I had a brain fart and was thinking the PAP had a larger OD than standard pex as well, being the ID is larger, but failed to realize the wall is thinner. Thanks for bringing that to my attention. It's been a long time since I used PAP.

SENWiEco

This may be of interest to this discussion - Comparative infra-red study of heat transfer plates - performed by Radiant Design and Supply

https://radiantdesignandsupply.com/theheatexchanger/2013/3/4/comparative-infra-red-study-of-heat-transfer-plates

Gordy

I’ve seen that one. Now do it with pex.

GroundUp

I ended up buying a stack of Joist Trak plates last week for the project. I haven't put them up yet as I had some surgery and am a little crippled up at the moment but the project is in motion. I will keep you updated as it progresses