Stripped bleeder screw

Paul_46

I have a hot water boiler with radiators in my townhome. Some of the radiators do not get warm at all. I checked the radiator for bleed valves but all the have is a flat-head screw. I cannot get these screws to budge and some of them are pretty badly stripped. What can I do to get these screws out and can I replace them with a valve and key system?

John Madden

Flat Head Screws.

Sounds like your radiators were originally set up for steam instead of hot water. Look to see if there are small "plugs" installed in a lower tapping on the radiators. There are a few radiators that only work with steam but because they have the screwdriver plugs at the top yours will work on hot water.
Best method to remove these is:
1) Shut down your system to make sure it won't fire.
2) Drain the system down to a level below the top of the lowest radiator.(you don't have to drain the boiler itself)
3) CAREFULLY center punch the screwdriver plug.
(If you hit the punch too hard you can crack the rad)
4) Start with a small drill bit and work your way up to a size 1/64" smaller than the plug diameter.
5) Use a "Pick" tool to remove what is left of the plug from the threads.
6) Use a 1/8" Tapered NPT tap to clean the threads. Go slow and Don't bottom out the tap. (again you can crack the rad).
7) Use a good quality thread dope on the new "coin/key" vent sparingly and screw in gently.
8) Refill system & bleed individual rads. Bring system back to normal operating pressure. Check for leaks.
9) Restart system.

If threads are badly damaged when plug is removed, or after retapping vent does not make up(fits loosley and won't tighten) you can drill the hole out just big enough to use a 1/4" pipe tap. Then insyall a 1/4" x 1/8" bushing before installing the vent.