By ‘heaters’ do you mean electrical heaters or baseboard hot water or steam radiators?
Baseboard radiators can be painted with any normal paint. Spray enamels or lacquers, latex house paint, almost anything. They never get above 150 degrees so it’s not a problem. Just scrape off any loose paint, clean them with a good degreaser like alcohol or lacquer thinner but make sure to keep the windows open and wear heavy vinyl gloves. Dry them or let them dry normally and paint. Job done.
If they are electrical heaters they do get warmer than radiators so using a ‘high heat’ lacquer in a spray can is your best bet. Clean as above, mask off the floors and walls with newspaper and masking tape and spray away.
With either set up use gloss paints. They hold up better and look better.
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