Cool Radiator

Any suggestions on why a radiator might not be hot? I gets warm, but not nearly like the others in my house. I see a valve on the side. Should I do something with it? Looks like it may take some sort of special tool or key to turn it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

is this a hot water base board system or electric base board heaters?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It is a very old boiler/radiator system. Still works like a charm except for that one radiatior.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If its a hot water system that is an air bleed valve at the top, open it till water comes out with the system running, ck boiler water level also.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
How do I open the valve? Don't I need to use some sort of special tool or key? I have keys for the faucets outside, but they are way too big to fit the radiator.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
You buy one, any hardware store.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.