Radiant Ceilings?

Swampgas

Would it be a viable design to use heat transfer plates such as Joist Trak on top of the gypsum wallboard ceiling in an attic space and cover it all with a lot of insulation to create a radiant ceiling instead of a radiant floor? It seems like it would be a much easier install than tearing down the basement ceiling to install a radiant floor. Not having to worry about the resistance of wood and the hardwood flooring seems like a benefit too.



I still like the idea of radiators with TRV's but I want to explore the options as my clients don't like the look.



Thanks

Rich_49

Radiant Ceiling

is certainly an option . The R value of your drywall is .5 for 5/8" rock . I would make sure that whomever insulates the attic joist spaces does not leave any gaps and does a real nice job .  Radiant ceilings actually work very well . You could even utilize the same tubes for chilled water and handle your sensible load in the warmer months for A/C , but that's a whole other discussion .  No chance of the Mrs of the house screwing up your heat emitters , cant put area rugs and furniture on the ceiling last time I checked .  

   We usually attach the joist trak perpendicular to the bottom of the ceiling framing and pack out parallel with 1" and attach the rock to that

Swampgas

In a retrofit

can you install above the existing wall board ceiling parallel to and between the joists? In some areas there is lath and plaster instead of wall board so the transfer plates would be 3/8" off the plaster sitting on the lath, that shouldn't diminish the system too much should it?



It would be nice to do the install without tearing down existing ceilings and getting into the living space. Fiberglass batts and then a heap of blown in cellulose over that should seal it pretty well.



Thanks

Rich_49

Plaster

will have an R value between .3 & .6 per 1/2" , add .3 for 3/8" lathe and you will be under R1 . It may very well work . I would certainly make sure that the joist Trak plates are in full contact with the ceiling though .  Insulate , insulate , insulate above the assembly .  Should work fine with an R 30 above , only really have to use R11 for the below framing install , I always use higher value . You may have to increase SWTs a bit but when you're starting out with temps just above 100* you can do it without much compromise to system or boiler efficiency (mod con) .

Swampgas

Thanks

I just may try it then. I want to specify a system so that when the home owners get bids we are looking at only apples and the HO's aren't drawn in by a cheap system. I am an architect and I know just enough to be dangerous so I think I can outline a system to use as a starting point. Something like this;



TT PT60 (54k design load)

P/S piping

Flow/check valves

Smart Tank

Expansion tank, 3 gal.

2 zones (radiant ceiling and radiators in basement)

Grundfoss variable speed pumps w/ isolation valves and drain

Mixing/temp control valve

Feed water pressure regulator

Joist Trak transfer plates w/ 1/2" PEX

Runtal panel radiators w/ TRV's



Am I missing anything?



Thanks

Gordy

Yes

You are probably going to find that getting good conduction contact in the areas with lath and plaster most difficult. Remember conduction is king in heat transfer, and this is what keeps swt low.



Depending on if the lath is wood, or metal the back side of the ceiling detail is going to be ugly with goobers of plaster forced between the lath. I would not think it would be a good idea scraping them off as this is how plaster is "keyed" in and this is how it gets holding power. Especially on a ceiling.



Your best product would be over the top of the present ceiling, and this is only if the ceiling joists can handle the load of an additional layer of strapping ,and drywall.





Radiant ceilings are very good emitters when done correctly. I have them myself, and actually they have more output potential than radiant floors. You can be sub 100* swt easily if the load allows.

Swampgas

Lath and plaster

The areas with wood lath and plaster have been covered with 1/2" drywall screwed into the joists so if need be the lath could be cut out in areas where the transfer plates would need to go and the plaster would stay in place. The keys have already been knocked off when the old insulation was vacuumed out. Would bedding the transfer plates in thinset on top of the plaster help enough with conduction to be worth the bother? Most areas are just 1/2" wall board where the original ceilings were taken out.



Sub 100 SWT sounds great but as this would be a system mixed with another zone of panel radiators I would need to have a higher swt for them and mix down for the ceiling correct? The panel radiators are in a basement area that is fairly well insulated and seldom used, would it be possible to run a very low temp through oversized radiators and squeak by without mixing down the temp for the ceiling?



Thanks for the feedback

Gordy

Ceiling heights

Are ceiling heights in the 8'-9- range?



So this house has been remodeled new drywall over plaster. Some areas the plaster was removed and dry walled.



How's the room for working in the areas above the ceilings to have radiant installed?



Only asking the questions because what sounds easy theoretically can be a real pain in the butt when actually doing it.



One comes to mind is how will you fasten the plate assembly to the back of the ceiling detail. In lathe areas you may get away with short screws. In drywall areas without lath could be a problem you may have to cut strapping between the joists to hold the assembly down tight to the drywall.

Swampgas

8'-4"

Ceiling height. The attic has a gable roof with decent space to work except for the outer 2 feet of the long walls of the house where the roof gets low and one would have to lay down to reach in there. How often is strapping installed and what does it consist of? It is just to keep the transfer plates tight to the ceiling yes?



The only part of any of this that sounds easy to me is Pex connections that aren't in the attic.



Thanks

ColoradoDave

Contact with ceiling

[quote]Plaster

will have an R value between .3 & .6 per 1/2" , add .3 for 3/8" lathe and you will be under R1 . It may very well work . [/quote]



This is just speculation, but I'd wonder if smoothing out the rough "top" side of the plaster with perhaps thinset so that the Trak panels can lay flat with full contact wouldn't solve the problem with increasing the R value of the ceiling too much for good transfer.

I've considered doing a radiant ceiling in my own home to add the benefit of radiant cooling in the future.

Gordy

Best performance

Is going to be over the top with a warmboard r, or Roth panels. Roth being the lightest. You have the head room. These systems will give the best heat transfer, and lowest swt.



Pushing through r1 is done a lot but again conduction is king.

SWEI

P/S piping

is it actually necessary for this design?

claudedesuza

Radient Ceiling

• I too have design my kitchen and living room with the similar radiant ceiling and it comes out with the great look. Initially I was concerned about the ceiling height, but 8'-4" is good.