Troubleshooting hot water radiator

Old 01-08-05, 12:41 PM
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Troubleshooting hot water radiator

Well, I just bought a house with a hot water radiator heating system. There are five radiators. Two downstairs and three upstairs. One of the upstairs ones, the bathroom rad, isn't getting hot. The entire thing is covered with paint so it took a while before I was able to crack the valve free and turn it. That didn't make a difference and it turns kind of easy so I'm thinking that the stem and seat are broken. Also, when I looked at the rad vent (which is completely covered in paint), and unscrewed it, I discovered that there were no threads remaining. The threads on the small valve are flattened at there really aren't any threads visible when I look inside the rad, which looks dry as a bone incidentally.

So, at least a few problems here. Where do I get a replacement radiator vent? What kinds of places would have them? The size looks to be around 1/8NPT. Do I drill and retap for 1/4NPT and use an adapter or do they make 1/4NPT vents? After I get this fixed, I need to mess with the valve. Any hints on removing and replacing? I can take pics if anyone wants to see.


Old 01-10-05, 06:21 PM
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One indication that something is wrong is that when you took out the vent, water didn't come shooting out. There should be water pressure at the vent at all times. If the threads can't be cleaned up with a 1/8" pipe tap, you may have to enlarge it to 1/4"like you suggested and use a bushing. You will need to find out where the water is and then you may get some heat up there.


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