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cleaning steam radiators and risers

I have a client that asked me these questions; What is the best way to clean steam radiators and risers? and what is the best type of paint to use. Just looking for some opinions, not sure what the answer should be.



  • jpf321
    jpf321 Member Posts: 1,568
    i suppose u mean the exterior?

    if you mean the exterior, rads can be shipped out for sandblasting. risers probably can't be shipped out easily .. i would try sandpaper or some other kind of stripping either chemical or heatgun.

    in terms of repainting .. i have seen it posted or written somewhere that a good quality standard latex paint would be fine .. temps rarely surpass 215dF .. so "high-heat/high-temp" paint is not necessary. they may stink a bit after initial repainting. when painting do be extra careful about all threads, vents and vent taps. the vent taps are standard 1/8" NPT .. so you can always remove the vent and go to a plumbing house and get some 1/8"NPT plugs to insert into the rad during painting which will be later removed and replaced with your vent.

    lastly it has been shown that the last coat of paint should be WHITE and NOT metallic like silver for maximum heat benefit from the rad. painting a rad silver or bronze for best heat is a myth that arose for various reasons.
    1-pipe Homeowner - Queens, NYC

    NEW: SlantFin Intrepid TR-30 + Tankless + Riello 40-F5 @ 0.85gph | OLD: Fitzgibbons 402 boiler + Beckett "SR" Oil Gun @ 1.75gph

    installed: 0-20oz/si gauge | vaporstat | hour-meter | gortons on all rads | 1pc G#2 + 1pc G#1 on each of 2 mains

    Connected EDR load: 371 sf venting load: 2.95cfm vent capacity: 4.62cfm
    my NEW system pics | my OLD system pics
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,285
    Careful sand blasting

    I prefer for radiators to be treated on site for finish if possible. sand blasting if done too aggressively can cause issues when none were visible before hand. Note I said visible not that they were not present. Dan has painting radiators in the archives. As he says "wander off the wall" you will enjoy it.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Big-Al_2
    Big-Al_2 Member Posts: 263
    edited December 2009
    High Heat Paint

    Personally, I've cleaned radiators for paint by sandblasting, pressure washing, and with sandpaper and a wire brush.  Sandblasting was the easiest.  The only problem I encountered with sandblasting is that the texture of the resulting iron was a little rough.  I don't think it removed much metal . . . just the many layers of paint that made it smooth.

    When I cleaned risers for painting, I used long strips of coarse abrasive cloth, wrapped around and pulled back and forth.  It took off the loose paint very well  . . . along with a layer of skin from my hands. 

    I have used regular hammer-tone spray enamel, engine paint, high-heat paint, and latex paint on steam system parts.

    Latex paint peeled after a couple of months.

    Regular spray enamel and engine enamel have held up just fine, with a nice gloss.  They did stink pretty badly for the first few weeks of the heating season.

    The high-heat spray paint (Rustoleum/Krylon brand) I bought at the local home center worked best. It's the kind that has pictures of stoves, grills etc. on the can.   It is available in a matte finish in white and almond.  It didn't stink much when heated, and the smell went away mostly in the first day or two.

    Radiators have an amazing amount of surface area.  A small radiator might take several cans of spray paint. 
  • jpf321
    jpf321 Member Posts: 1,568
    very good to know

    thanks big-al... first hand experience and result reporting is always the best. so high-heat paint wins the rad paint battle.
    1-pipe Homeowner - Queens, NYC

    NEW: SlantFin Intrepid TR-30 + Tankless + Riello 40-F5 @ 0.85gph | OLD: Fitzgibbons 402 boiler + Beckett "SR" Oil Gun @ 1.75gph

    installed: 0-20oz/si gauge | vaporstat | hour-meter | gortons on all rads | 1pc G#2 + 1pc G#1 on each of 2 mains

    Connected EDR load: 371 sf venting load: 2.95cfm vent capacity: 4.62cfm
    my NEW system pics | my OLD system pics
  • Big-Al_2
    Big-Al_2 Member Posts: 263
    edited December 2009

    The hammer-tone brown sure looks elegant though.  It's probably worth putting up with the odor . . . if you like that look.

  • high heat paint

    A bit late, but I will add my experience.

    Latex may be able to handle the heat of the pipes and radiators, but it can't take it over time and so it will eventually peel and flake.

    Regular enamel spray paint will suffer the same fate.

    The high-heat paint that you can get for grills and things works great.  But I think that the matte finish is unremarkable and the silver gloss looks silly.  And if you are lucky enough to have any kind of cast details on your radiators, they will kind of get lost in the matte finish.  The same companies make high-heat gloss, but you have to brush it on.

    Engine spray paint works great.  It can take the temperatures and you can get it in a very nice gloss finish .. and lots of colors if that is your thing.  In fact, the finish kind of looks like powder-coating.

    I did all of my radiators in the matte high heat because I couldn't find it in gloss.  I really hated the matte finish so I went on a quest for high heat sprayable gloss.  That's when I discovered the engine paint.  I recoated them all with that and they look incredible.  Some people have said that the engine paint doesn't hold up as well as the high-heat, but they are both rated to temps way beyond what a steam radiator could hit.
  • Jamie Hall
    Jamie Hall Member Posts: 21,573
    We have had

    no problems with flaking or peeling -- not yet, at least (about 3 to 5 years) -- except on one riser where we couldn't do a proper surface prep.  The procedure we use is scrape as much old paint off as possible, then wire brush (hand, not power -- but you might be able to get away with power) hard.  The metal or rust (either one!) must be bright and hard.  Then a coat of high quality (we use Benjamin Moore, but there are other good brands) oil base primer.  Then whatever colour we need (usually to match the walls, occasionaly to match the trim) of top quality acrylic (again BM) paint.  The one place we couldn't do the scraping and wire brushing (would you believe silk wall paper?) has peeled.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Luv'nsteam
    Luv'nsteam Member Posts: 278
    Painting steam radiators

    I have painted many, many steam rads and several risers.  To date, not one has peeled.  The trick, like all painting, is in the preparation.  Sand blasting is thorough, but who wants to truck several, several hundred pound iron radiators to someones shop for sand blasting?

    If they are rough, have peeling or chipped paint, sanding by hand until the peeling area is blended and smooth is a good start.  TSP (tri-sodium phosphate or a substitute if n/a in your state), bleach & H2O are the things that work followed by a very thorough rinsing.  I have trucked some out back and power washed them, I have scrubbed them in place by hand.  Whatever is most convenient for the person doing the prep work.

    I have used enamel, lacquer, latex and some specialty high-temp coatings/paint.  With proper prep, they have all worked and lasted just fine.  For me, it was what my client wanted, or at home, the color my lovely wife wanted.  After cleaning, primer is a must if you want the paint to to adhere to the rad.  Don't wanna use primer?  Well, it's your time, you decide.

    Our rads at home are painted with Rustoleum "Pounded Copper" paint.  They are beautiful and most important, my wife likes them. :  )

    As for application, they require three to eight cans of spray paint, depending on the size.  If you use a brush, a half quart to one quart for a medium to large radiator.

    Both application methods suck if you want good and complete coverage.  Sorry, I can't lie to you.  Painting a radiator completely is not fun.  However, the final product is rewarding.  And if you take your time and do it right, it will last a long time.

    Good luck,

    Mike Mumma
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