What to line the inside of my in-floor radiator boxes with?

adamfre

WOW!! Finally a non-plumbing related question from me
I think this weekend I will start working on rebuilding the boxes my radiators sit in that are beneath my floors. The old boxes they were in originally were lined with a thin gauge sheet metal, painted black. I was tossing around the idea of using sheet metal for mine, but not paint it with the hopes that the reflective surface might radiate more heat up into the room. Thoughts?

As you can see in the pic, there is not much left of my original boxes. LOL

Danny Scully

Seems like a job for bubble foil.

adamfre

I saw a post about the bubble foil earlier, I plan to do a little research on that product tonight.

adamfre

I guess my concern with the Reflectix product would be if it would melt or not. It's rated up to 180f which is pretty high, however using it to line a box I'll be sticking a steam radiator in... Wonder how hot the inside of that box might get? I think the radiator could potentially exceed 180...??

Hap_Hazzard

I think you have to count on the temperature routinely reaching 200°F. It may not melt the insulation, but it would probably release any volatile compounds it might contain. Also, you'd need to make sure there's at least a 1" air space between the radiator and the insulation.

kcopp

1" poly-iso foam board and foil tape?
You could actually just make it out of that....

JUGHNE

The company I buy my pipe insulation from had a product that was high density 2' X 4' 1" thick compressed fiberglas that was foil covered. No dust or floating fibers.
Poly or foam anything might outgas at 200 degrees.

The original owners might have that painted black so as you look down thru the grill you would see nothing; just like painting the wall cavity black behind a high wall return air grill/face.

I really enjoy watching someone dedicated to restoration!
Just watching I said, not doing.

adamfre

The original boxes were constructed using tongue in groove boards, so I am pretty sure I can just use a decant grade of plywood to construct the boxes. I'll construct the boxes to the same dimensions as the old ones (figure they worked for however long before they rotted away) With regards to lining the inside of the box, I'll just use flashing, with the non painted side facing the radiator. I'll be using 6"duct to re-build the fresh air intake however I'm waffling on just following the original design of just sticking it into the side of the box, or maybe feeding it into the center of the bottom of the box. If anyone has a suggestion there I'd love to hear it.
It's been a fun project! Getting close to being finished.... If I never have to use a RIDGID model 700 hand held threader again....

JUGHNE

The Rigid 600 is a little friendlier if you don't need more than 1 1/4".

I have always avoided large grills in the floor for cold return air.
(I know these are gravity supplies in your case). Reason being to not have a pipe hole in the bottom for me was that anything going into that floor grate would go down the pipe. Dirt, toys, loose change etc. If you connect into the side of the box then the box will act as a debris collector to be vacuumed out on occasion. IMO

adamfre

Goooood point! So many lego's and green army men go there..... lol

KC_Jones

I think I would add a trap door to the bottom of the entire enclosure for cleaning purposes. It's not just removing debris, but cleaning the rads in there.

Another option could be making the entire enclosure removable with something like tool box latches.

adamfre

Not a bad idea, @KC_Jones. I had not thought about making the bottoms easily removable.

hot_rod

kcopp said:

1" poly-iso foam board and foil tape?
You could actually just make it out of that....

The solar thermal collector manufacturers are using a high temperature foil faced ISO board. Dow Thermax is a higher temperature product that the hardware store Dow Tuff R board