Oil-filled radiators can be found in different stores. Some places include Amazon, Home Depot, Target, or even at Sears. They come in different colors.
Why not try Antique Plumbing and Radiators? Stocking over 4500 cast iron radiators, you're sure to find the perfect one for your bathroom. All radiators are pressure tested and come with a one year guarantee from date of purchase.
Yes
They transfer heat by the radiation
Usually there is a valve that you can open to let the air out .
Radiators are made of a lot of metals with high melting points (example: Aluminum)
take them off, then get a cloth and clean it. And you can hoover it up a little.
Your home air conditioner filter might be turning black because it is damp or moldy. It might also be turning black because it is filled with dust.
Alarm system
Answer There might be air trapped in the radiator, try bleeding. It's usually a flow problem. If the valves on all of the radiators are wide open, the steam will flow through the path of least resistance, often leaving some of the radiators lacking for heat. Try turning down the flow on some of the hotter radiators. You will need to spend a little time adjusting the flow... assuming that you have flow adjusting valves on the radiators. These old cast iron radiators have sections that are bolted together. Each section has a gasket to keep the steam or hot water INSIDE the radiator. Of course these old radiators collect rust over the years unless you are very careful and scientific about your water chemistry (most folks are not). You probably have a plugged hole in one of the gaskets between the section of the radiator that is getting hot and the section that is not getting hot. This "cold" section is being bypassed and not receiving any flow.
If these are old style hot water radiators (the tall cast iron type) they probably are air-locked and need to be bled. There is a valve at one end near the bottom to do this. Open this valve slowly and with caution since it will initially release trapped air (under pressure) and then very hot water. Close the valve when it stops sputtering from trapped air. If they are electric radiators, they might be burned out or have bad electrical connections. You will need an electrician to correct this problem.
air
There are many places one might go to find a home finance calculator. In addition to one's financial advisor's website, one might also find a calculator on one's bank or credit union website.