my method for refurbishing cast iron radiators

[cadrad]

I removed 6 of my radiators so I could strip the baseboards and get to the backsides for painting. they were a little hard to loosen the fittings since they had been painted over and probably not loosened since the 70's, but the came loose with a little muscle. I used a 2x4 to muscle the radiators out of position onto some plastic sheeting. I then used a scraper and a wire brush to remove the loose paint feathered the edges with a power sander, did what I needed to do to the wall, primed them by brush with oil based primer, and then taped plastic up all around the area. I used a paint sprayer to get into all of the fins. I am painting all of the radiators in the house a dark coppery bronze color, and I painted the lower valve brass colored and the pipes a dark iron color with high gloss black knobs. The upper valves are nickel so I stripped and polished them and painted those knobs gloss black too (that is what color they were originally). The areas where the loose paint was removed are visible as slight recesses upon close inspection but not noticeable from a normal radiator viewing distance. The overall effect is that they are all "natural" ( circa the ideas of a radiator 1916) unpainted. They were pretty easy to hook back up (some more than others) they all hooked up eventually. They went through a season of heating with no leaks. I didn't have the time (as I did this in the late fall), money or muscle power to remove the radiators from the house for sandblasing or powdercoating and this method end up costing me maybe $100 for paint, sandpaper, ect, but I have all of that left over for the rest when we get to them.

[joeny1980 (WavyGlass)]

Can you post a photo?

[Ireland House]

This may be a good cosmetic fix, but it doesn't do your power bill any favors. We have one of Illinois best boiler guys working on our house. He assures us that it is well worth the investment to have the radiators stripped and repainted. The household paint actually insulates the metal, trapping the heat inside the radiator. Multiple layers of modern paint can actually increase your heating bill substantially! We have a local company that will dip and repaint the radiators for about $250. The paint they use is a metallic paint that helps the heat transfer. I know we want our power bill as low as possible so we can put more money into other repairs. It seems like a huge investment, but it is a one time gig.

[Paladin (WavyGlass)]

Hey Granville,

Do you think you could find out what type of paint that guy is using & let me know? I have several old radiators that need some TLC and I wasn't going to remove them/begin refurbishing them until I had a decent paint to finish them with. Their from the late '20's & still run great, one in particular needs a bit of help & I'd like to tackle that one this summer, thanks.

P

[KevinSteve (WavyGlass)]

I also want to know, What type of paint they are using ? You also want some good quality paint which makes your radiator a new one.

[cadrad]

It is a proven fact that metallic paint of any kind reduces the radiators ability to transfer heat. the best color if you are only concerned about radiation is flat black. I have also read that only the top layer of paint matters, that the heat will move through the other layers with no problem. I do not have the rescources to have them removed and taken away for stripping and refinishing at this time.

[Faust (WavyGlass)]

Re: Paint. As noted it has been proven that black is the best color for heat transfer (look at motorcycle engines). Still, I expect the differences are marginal. Auto supply shops have engine enamel, but probably not in a color you would approve of in your living room. Still, "high heat" paints are not difficult to find.

I don't find sand blasting to be expensive, although moving the radiators may be a greater cost factor. If you can get them to the yard, you might try "aircraft paint remover" (auto supply stores) and a pressure washer. Harbor Freight sells sand blasting guns for about $20.00, you will use more sand than you imagined.

[maxhall1023]

We had 2 of our cast iron radiators sandblasted primed and painted by a local company for $65 a piece. Granted we had to get the radiators there and this doesn't include cost of the paint/primer but still a great deal. I'm an avid DIYer but after researching renting a sandblaster, the cost of aggregate, setting up a semi enclosed area to entrap aggregate I opted for having it done. It actually turned out cheaper and I'm sure a much better finish than I could achieve. We used a BM oil based primer and Modern Masters for the paint. Modern Masters is quite expensive but 1 gallon will get you 5-7 radiators depending on size. When we went to pick them up the owner asked where he could find that paint because all of the other people with radiators who had gone with the standard white were asking about it.

You can also contact them to send you actual paint swatches since online and brochure colors can be a little inaccurate.

I'm an engineer by trade and I'm very sensitive to energy conservation, and while the metallic paint does lessen the output of a radiator I reasoned by stripping layers of paint and adding my metallic paint the overall effect would probably be negligible to slightly better than before (I was right). I can't site the source but I've read that the energy loss is ~20% with metallic paint. You also have to remember these houses didn't have insulation so as you do things to increase the envelope of your house you're effectively making your radiators too large for the room they're in anyways. Lets be honest if the bottom line was money saving and energy efficiency none of us would own an old house.

[heartwood]

interesting conversation...

i agree, if you're looking for the most efficient house on the block, the oldest house won't be your cuppa tea...i've not had radiators in a house i've owned...always assumed there was a knob adjustment to regulate the heat on each radiator...wouldn't one want to adjust the radiator down in a well insulated old house? how do you pronounce it--rad-ee-a-tor or ray-dee-a-tor? i'm the latter........

...jade

[maxhall1023]

Jade one would think you could just close the valve a little and reduce the heat output but most radiator valves are gate valves vs globe valves which means they have poor throttling characteristics (they're really hard to fine tune). What you can do is install TRV or Thermostatically Regulated Valves that allow you to control the heat output of each individual radiator based off of room temp. These normally run you around $80-140 per valve and from a purist standpoint detract from the overall look of a radiator (plastic shell). These are definitely a good way to go if you're radiators are too hot or you have some secondary type of heating.