Hello Everyone,

I live in NYC and have radiator steam heat. My apartment generally gets HOT, but not quite hot enough that turning the radiators off all together would be a great idea. (Nope, I don't have a thermostat to control the heat directly, else this wouldn't be necessary.)
To help address this, I have built a radiator enclosure designed to keep as much of the radiator heat contained inside as possible - EXCEPT when the room drops below a certain temperature.
This project isn't that expensive, the most costly item is a modified "semi-smart" vent booster that is used. Think total project under $100, but you can likely find ways to make this even cheaper.

Note: This is generally inspired by a system from RadiatorLabs called the cozy - last I checked they weren't really making their product available to individuals but much of the core concept is similar. (For any people who have read/know too much about radiators - the system here is a single pipe steam heat system. This design should work with pretty much any radiator system.)

More notes: Your building may not like it if you mess with or make an enclosure for your radiators. Radiators get hot, don't get burned - steam can be some thing like 220F. Also anything you do here, you 100% accept the sole risk for, it might be a bad idea. Go ask your responsible friends first to see if they think you shouldn't do this...

Supplies

Note: I used some amazon referral links - so in the unlikely event that anyone actually uses / buys any of this... perhaps I'll get some $? "This intructable contains references to products from one or more of our advisers. We may receive compensation when you click on links to those products."

Wood ~$20
1 1/4" drill bit (or something else to make holes) this works, I used something a bit different though. ~$10
Saw or some way to cut wood
Sharp cutting tool / X-Acto knife
Miscellaneous screws or fasteners
AC Infinity AirTap T4 (Modified/used in a warranty voiding way.) ~$60
A small piece of metal / aluminum helping to act as an air barrier.
Some insulation with an adhesive back like this ~$20
Some Caulk, although maybe silicone would be better for high temps
Temperature sensor with longer wire EBay/AliExpress (Temperature Sensor Wire Cable Probe For Arduino) $5

Depending what tools you already have - this should really be under $100 - you can do this even cheaper...

Step 1: General Concept / Understanding

Just want to explain how this is designed to work in theory.

First the wood and insulation are meant to keep in as much of the hot air as possible. Some will still find its way out / the wood may still get quite warm.
The smart vent is modified in a way, so that its fans will turn on when the room temperature is below a set point (you can set the temp.)
When the fan is on, air is drawn into the radiator cover from the holes that were drilled, it moves through the radiator where it is warmed and is expelled into the room from the vent.
Additionally, there is a barrier (a piece of metal) helping to prevent air from flowing from the air holes directly out the air vent. If air went directly in then out, it wouldn't really get warmed. We want it to flow through / around the radiator before it gets expelled back into the room.

See image of how this would work in theory.

This design absolutely has some limitations. Ex. what if the room is cold and the radiators weren't recently on (filled with steam) then air would get drawn in and then expelled without anything to heat it up. This solution/design is really meant for places that are generally warm enough to begin with and prevent overheating - its not going to do much (anything) when it comes to making a room warmer.

Step 2: Measure Twice (or More), Cut Once (hopefully)

The radiators I have are partly in wall, so the covering I'm making covers the Top and Front of the radiator. The sides / bottom are already enclosed - you might need a back and sides for your cover.
Measure the relevant portions, acquire some wood and have it cut down to the correct sizes. You will see me making sure the pieces fit after cutting them down.
Next you will see where I drilled the air intake holes and the opening for the vent booster.

If I did this again, I may have made the air holes even lower to the ground, as currently they might cause some additional heat to escape, based on how high I drilled them.

IMG_8934 copy.tiff
Download

Step 3: Add the Adhesive Backed Insulation!

To help increase how much heat stays in the cover I added insulation to the interior portions of the wood cover. It's likely a good idea to overlap the insulation / make sure it covers any places where its likely heat can escape, ex. where the wood meets the wall or another surface.
Depending on your situation, perhaps you may want to double up the insulation or use a different material for a better thermal barrier.
Additionally, using an X-Acto knife (or something else very sharp) is useful in cutting out those small holes in the insulation.

Step 4: Install the Wood Coverings!

Put your radiator cover in place. I used some screws to help hold the cover in - your situation may be different.
I also ended up caulking around the wood (perhaps some high temp silicon would have been a better idea).
Additionally, I painted one white - but I think it looked better natural.
I'm missing a photo! Also, I put a thin piece of aluminum vertically to separate the area with the air holes and the area with the opening for the vent. The idea is to make sure the air that gets sucked into the air holes flows around/through the radiator, not just in one opening and out the other.

Step 5: Modify the Vent!

Voiding warranties / at your own risk :)

Okay, a couple things to know about this vent. It's really intended as a register booster for use in home/suburban forced air systems. What does that mean? Basically if you were out in the suburbs and someone had a room that doesn't get enough AC in the summer or heat in the winter - this booster is used to pull extra air through the system and out a particular vent.
It can be turned on/off manually or based on temperature. However, the temperature sensor was placed to monitor the temperature inside the vent - not inside the room. This doesn't work for me, as I want it to force warm air based on the temp in the room, not the temp of a vent or the temp inside the radiator cover.
We're going to open up the vent then we can do one of two main things:
- [OPTION 1, RECOMMENDED] You can get a compatible temperature sensor with a longer wire. - its a matter of unplugging the existing one from the small board and plugging the new one in. The only tricky portion of this is there seems to be a bunch of glue used to help keep these stay in place - you can pry the glue off - just be sure you are gentle and don't become too aggressive / end up breaking or smacking part of the board with a sharp tool when you really should be.
- [OPTION 2, Works but above way is better] We can move the temp sensor so that it will be just outside the vent (this works ok) but the temp right outside the vent isn't always going to be the temp in an average area of the room. It can also be quickly impacted by the temp of the air coming out of the vent. (Ex. If we have the vent set to turn on at 68 F, if it turns on and pulls hot air out from the radiator it might move the temp right near the vent up to 70F quickly, resulting in the vent turning off - then dropping and turning back on - a bunch of times.
- [ALTERNATIVE OPTION 3 - Requires more gizmos] This requires having smart outlets (the google / Alexa compatible kind) a smart temp sensor and use of an app/software tool called IFTTT. Basically you can set the vent to always on and plug it into a smart outlet. Using the smart temp sensor and IFTTT you can set the outlet to only turn on when the smart temp sensor reaches a particular temp. This should work fine, you wouldn't need to modify the vent and you could put the smart temp sensor wherever you want. However, it relies on an internet connect and those various devices always being able to talk to each other using IFTTT.
  We can see that the new thermometer works pretty accurately - within about a degree of another thermometer I have.

Step 6: Protect the Vent!

Since we're using the vent in potentially a higher temp environment then it was designed for, I'm going to use some of the excess insulation on the vent itself / help shield the IC board from the continuous heat. (Is this necessary? I don't know, maybe not?).
Additionally, since the insulation has a foil/metal back I have covered it in electrical tape. This is to help prevent any type of short if the insulation ever becomes loose and makes contact with the IC board.

Step 7: Thoughts - Closing Out

What else you can do:

Thicker wood would make for better insulation than the thin hobby panel I used for the front of my enclosure. If you have real tools etc. go thicker.
Additionally, you can think of including something that absorbs heat insidfe the enclosure too - this should enable the temp inside the enclosure to stay warmer longer. This is useful in case the temp of your room drops and the radiator is no longer on (filled with steam) at the moment. For instance, bricks are good at absorbing heat - if you put some inside the empty space of the enclosure they will absorb some heat - which can be useful if your system is trying to heat the room after the radiator has turned off.

Feel free to comment if there are questions or anything else you want to see more of etc.

Step 8: Almost Done!

You're pretty much all set at this point. You can put the vent into the opening if you haven't already.
One slightly counterintuitive thing about this, is that you need to set the vent to the mode where it shows a snowflake icon, not a fire icon. Then set the temp to whatever degrees you want. Ex. 68 will turn the vent on when it sense the temperature being 68 degrees F or lower.