Radiators are hot topics for apartment dwellers. We love them, we hate them, we cover them, we camouflage them, we paint them, we do makeover after makeover trying to help them blend in. If yours sticks out like a sore thumb or just use a refresh you maybe wondering if paint affects the radiator's efficiency. Here's what you need to know before you get out your paintbrush.
In the home renovation world, there is also lots of disagreement and conversation about radiators, and the effect of paint on their efficacy. If you want a little glimpse of the back and forth that happens, check out this long and particularly painful feed. Or this one. Or even this one.
According to the New York Times, these clunky old metal systems work by both radiation and convective heat:
Radiation accounts for only a small percentage of the heat given off by the radiator; a much higher percentage of the heat is distributed by means of convection - as the radiator warms the air next to it, this heated air rises, drawing cool air into and through the radiator from underneath. This movement of air sets up vertical currents that will distribute heated air throughout the room.
We aren't academics, but after reading about the issue, this is our takeaway: while paint might effect the radiant part of the heating process, it probably has a negligible impact on a radiator's overall efficiency. It's much more important that the air can move freely around the radiator. This is why radiators are designed the way they are, with lots of negative space, and why you should think twice when picking a decorative cover, or hanging curtains, that might restrict air flow.
It is perhaps true that multiple coats of paint act as insulation, making it less efficient. It's akin to putting on multiple jackets, keeping the heat in instead of allowing it to transfer into the air. But again, everything we've read suggests it's pretty minimal. The same goes for color. Painting a radiator a dark matte color might make it conduct heat a little bit better. But it won't be as noticeable as, say, touching the dark steering wheel in your parked car in the middle of summer and searing your flesh off.
So, bottom line, should you paint? Sure, go for it, especially if the appearance is bothering you, but don't do it to improve performance. Color doesn't really matter, so either paint them to blend in with the walls, or get creative and make them into a real statement. But, if you want to be absolutely sure, hold off on that makeover until you remove the old paint, stripping it down while you binge watch the next biggest Netflix series. (Check for lead if you think the paint is really old!) Or better yet, send it out to be sandblasted.
This Old House suggests the use of high heat enamel, which it says can stand the temperatures and won't flake or peel off (although there's debate about the need for this as well). If there is any rust on the metal, spot prime first before painting. Using a paint sprayer is ideal, but canned spray paint, or brush on paint, is do-able. Average Inspired has a good post on the topic and shares what's she's learned after painting a couple of radiators in her house.
Have any more info that can shed light on the topic? Let's start our own long, painful thread here!