Radiator Reflector Panels - Thoughts?

BrianT1077

I was just wondering what everyone thinks about putting Aluminum Radiator Reflector Panels behind their steam radiators in order to reflect more of the heat out into the room instead of the wall absorbing the heat. From my reading on this subject I understand this is done a lot throughout Europe and with success. Thoughts???

DanHolohan

They work. This was part of the Empire State Building's heating retrofit a few years back, part of what got them a LEED Gold rating.

BrianT1077

I am thinking of trying this:
http://www.lowes.com/pd/Reflectix-50-sq-ft-Reflective-Roll-Insulation-24-in-W-x-25-ft-L/3011904

vaporvac

@BrianT1077 , I have used similar and one can really feel the difference. I actually bought mine in England years ago where is is sold for that purpose. It was applied with wallpaper paste. Somewhere there's some IR pics from a few years ago, where on of the pros experimented with two side-by-side rooms. It was obvious, but I already suspected as much. ALL my old semi-recessed rads had a reflective metal piece custom installed originally, so this isn't a new concept.
Thanks for the Empire State Building info., @Dan Holohan ; I wasn't aware of that detail.

SWEI

Bubble wrap definitely works. If I were remodeling and wanted longevity, I'd probably use XPS and polished aluminum sheet metal.

BrianT1077

Well tonight I thought I would try some Reflectix in the dining room behind the radiator. I stapled it to the wall. I will do the other rads over the next few days. Stuff is actually very easy to use. Think I should trim off the part that covers the molding? Thoughts?

marcusjh

This brings back memories for me. Long ago, my Dad read an article somewhere about reflecting heat back into a room with aluminum reflectors. So he took some cardboard, lined it with aluminum foil, and tacked it to the wall behind his radiator. The cardboard was from a large box, and he scored the top of it so it angled over the top of the radiator. I remember the top of the reflector eventually resting down on top of the radiator, and getting really hot. I think his room was the only one that had one, and 'm not sure it worked very well for him. He finally got rid of it in the 90's.

I always wondered if one of those heat generated fans would work on a radiator, but I'm not sure if they get hot enough (aren't they for wood stoves?).

LionA29

Looks fine, I used the foil faced styrofoam.

rosaliedipietro2

Would a piece of sheet metal work well?

SteamingatMohawk

Anything which includes some insulating value is better than just sheet metal.

SteamingatMohawk

@rosaliedipietro2 I suggest you read your messages, that's the envelope at the top of the page.

random12345

rosaliedipietro2 said:

Would a piece of sheet metal work well?

Forget sheet metal. Too expensive, and not that great. Aluminum foil. Either tape it to the wall with aluminum high temp flue tape or get some craft wire, shape it into a rectangle and then take sheets of foil and put it over that like you would spread a cloth canvas over a wood frame. Place the foil wrapped frame behind the rad. As far as I can tell aluminum foil has one of the highest infrared reflectivities of any material at the wavelength of light emitted by a steam radiator that is at 215 F.

https://sciencedirect.com/science/article/pii/S2215017X1930373X

According the Wien's displacement law, a steam rad at 215 F (374 K) emits peak blackbody radiation at around 7731 nm. According to the article above, the total reflectivity of aluminum foil is nearly 100% at 2500 nm. It should be even higher at longer wavelengths. At least that's my understanding.

I've tried it, and the walls behind my rads are no longer hot. It works.

ethicalpaul

SteamingatMohawk said:

Anything which includes some insulating value is better than just sheet metal.

Depends what the goal is. If the goal is to reflect radiant IR back into the room instead of letting the wall absorb it, insulating material is irrelevant.

> This was part of the Empire State Building's heating retrofit a few years back, part of what got them a LEED Gold rating.

was the other part a healthy donation to LEED? 😂

SteamingatMohawk

My point is to use something more than just sheet metal, like the aluminized bubble stuff, foil faced insulation, etc.

Regarding infrared reflectivity, I have to take the Sgt. Schultz plea, " I know nothing"...probably about a lot of other subjects, too.

hot_rod

I think the more polished the better. I bought some mirror finish contact paper to build a solar oven once. Any dust or rain deposits really cut down on the power.
Be interesting to find an old mirror at a second hand shop to compare to the bubble foil

We found the same issue with reflective foil under radiant staple up. Once it got a layer of dust, the reflectivity was gone, output dropped 

Plus the mirror would show where the painting missed🥴

dabrakeman

I use the carboard and aluminum foil method on a couple radiators. No tacking in place. Couple times a season I will just reach behind the radiator, pull it out and wipe off any dust with a dry cloth and reinsert behind the radiator. Infinitely customizable, easy to maintain and cheap. I also keep them a bit in from the outer edges of the radiator so as to not be very visible.

SteamingatMohawk

I wonder if using a dry cloth could cause static electricity which could attract dust to the foil?

random12345

dabrakeman said:

I use the carboard and aluminum foil method on a couple radiators. No tacking in place. Couple times a season I will just reach behind the radiator, pull it out and wipe off any dust with a dry cloth and reinsert behind the radiator. Infinitely customizable, easy to maintain and cheap. I also keep them a bit in from the outer edges of the radiator so as to not be very visible.

Even easier if it works. My rads are very close to the wall. I was concerned the cardboard wouldn't handle the heat.

dabrakeman

No issue with level of heat and safety with cardboard. Closer the radiator is to the wall likely the higher the potential gains.

random12345

Ok. Maybe I'll give it a try...

bhiggins

When I had a boiler and rads I did that, aluminum foil and masonite. I never tested it, so I can't say about effectiveness. I do recall how pleasant it was to sit on a warm radiator, for a few moments, anyway.

mvickers

Not aesthetically pleasing, so if it matters, what does the keeper of the kave say?  Small, slim line, 12vdc vehicle fans behind the radiators on low speed

mvickers

That is, the foil's not aesthetically pleasing, the fans attached to the radiators would essentially disappear 

JanitorJim

I believe I read one time about a reflective paint that can be tinted to match any color. Would painting this on the walls behind radiators accomplish the desired radiation directing effect? For that matter maybe using this paint on all exterior walls would be a good idea for energy retention? 

Stuart Rogers

The panels definitely work, and pay for themselves quickly. I recommend them without hesitation.

I spearheaded the installation of reflective panels in my building in 2011. (Four-storey brick, 25-unit co-op in Toronto, built 1925; Weil McLean 1280 steam boiler with outdoor reset, Powerflame modulating burner.) I attach the report I prepared for our Board (ASAI = Amsterdam Square Apartments Inc.), which was accepted and acted upon. The Novitherm panels are designed specifically for radiators, and are shaped to increase convective airflow in addition to directly reflecting IR frequencies. (The airflow improvement is only an advantage if there is no cabinet over the rad, of course.)

Thermograms taken a few years before for a different purpose showed heat penetration through the exterior walls where rads were located almost as brightly as what was being lost through 90-year-old single pane non-weatherstripped steel windows. (Don't have "after" shots to compare, unfortunately.)

We were able to apply for an energy-saver grant from our gas supplier, and the estimate of annual gas savings was about equal to the fuel burned in April of that year (7900 cubic metres). At the time, we were paying CDN$0.33/cu. m., so the panels paid for themselves in under two years.

(These photos are in the report but duplicated here for tl;dr )
The panels for the test were on the wall behind only the top half of the rad.
Test Rad Before:

Test Rad After (note additional heat reflected from the supply pipe, which is hidden by the photo legend):

and just 'cause I'm proud of our home with its new windows and cornice

carlboiler

https://www.wtamu.edu/~cbaird/sq/2016/03/08/is-metal-a-good-heat-shield/

Check this out.

random12345

@Stuart Rogers I believe I spoke with someone at Novitherm who said these were not suitable for steam radiators, hot water only. Plastic may not be able to withstand the higher temps.