Gas and Oil Home Heating Furnaces - changing radiator values

:) I am new to this site. Please forgive my ignorance. What is meant by thread? Here is my radiator problem. I need to replace valves on two water radiators. I am unable to loosen the valves from the pipes that go to the furnace because there is not enough clearance between the valves and the unions once I unloosen the knuts on the unions. The furnace pipes extend above the floor only a few inches and the holes cut for them don't allow me to lean them away from the unions so I can unscrew the valves. (I learned the word union from a local supply company so my plumbing vocabulary is by no means extensive.) Please bear with me as I try to describe a possible solution for your analysis. Looking at the radiators beginning where the valves are attached to the unions and then the unions go into the radiators I notice that the unions have threads. These threads go in to the radiators but appear to be attached to the radiators by another knut. These knuts are different looking than the ones holding the union to the valve. They are thinner and are shaped somewhat simiular to the kind of chrome covered knuts on a kitchen sink drainpipe assembly. If I unloosen the narrow knut will that allow me to side the union deeper into the radiator therefore giving me the desired clearance? If not, What would you suggest? I have thought of unscrewing the other pipes leading out of the radiators on the other end and then just pushing the radiators back enough to clear the valves but I have the same type of clearance and floor pipe issues on tose ends as well. Thank you for your help. dlf

The thinner nut you are referring to is not a nut at all. It is a bushing int he radiator to reduce the size of the opening to the size of the union on your rad valve.

The only solution is to work on the right side of the radiator first and as you loosen the elbow from the vertical pipe, move the radiator slightly forward. After about 1/8 of a turn it will be separated enough from the union that you will be able to remove the radiator. Bear in mind that the task you are attempting is not for the faint of heart. It can result in the proverbial can-o-worms. If you damage the vertical pipe, you will be in the carpentry business before you know it. And since you will need to replace the part of the union that goes into the radiator also (whether you like it or not), you may have different measurements from center to center when you are finished. That will cause a problen when re-installing the radiator. Just getting everything apart can be a chore because tolerances are close between the union nut and the radiator and between the floor and the underside of the valve.

Is there a possibility that you could take a drill and drill a series of 1/4" holes around the outside part of the pipe on the valve end of the radiator? Then you could take a narrow sabre saw blade and remove the material between the holes and give yourself a little more room to work. You could add an ecsutcheon around the pipe if it gets ugly. That's what was done back in the day.

Good Luck

Ken