Problem: Radiator valve leaks
around stem, dripping onto floor.
Background: If you have an old- style radiator that
has a valve which is leaking, take care of the problem as
soon as possible. The leak can damage the floor, and even
the ceiling below the radiator. Often valves leak around
the stem because the packing inside the packing nut is
worn or insufficient, or because the packing nut itself is
loose. First try tightening the packing nut. If the leak
persists, you will probably have to repack the valve stem.
Many older radiator valves were built so that the packing
nut can be raised without lowering the pressure in the
radiator. In a hot-water system, where the valve permits
water or steam to escape after the valve is closed and the
packing nut is loosened, the level of water must be
lowered below the height of the valve by opening the
system’s drain cock. With a steam system, first reduce the
pressure by allowing the boiler to cool.
What to do: Two forms of packing material can be
used to repack the valve stem: different size washers or
packing cord. If you use washers, loosen the screw holding
the valve handle, remove the handle and withdraw the
packing nut from the stem. Take out the old packing and
slip the new packing washers over the stem. (Use the right
number and size of washers to fill the packing space in
the nut.) If using cord, wrap enough around the valve stem
to fill the packing space in the nut. The nut should be
tight enough to keep water and steam from escaping, but
not so tight that it keeps excessive friction on the stem
when the valve is turned.
Special advice: With a steam-heating system, let
the fire go out, or at least have a low head of steam,
before starting to work on the valves. After the system is
cool enough to work on, close the valve tightly and
unscrew the packing nut at the base of the stem. Pack the
space between the inside of the nut and stem with metallic
packing compound, using a small screw driver. It may be
easier to pack the nut if it is removed from the stem. To
do this, remove the handle and lift the nut from the stem.
After the nut has been repacked, screw it down tightly and
refill the system, following the instructions in the
Helpful hint: If you
are unsure about proper procedures with an older heating
system, call a heating equipment specialist. Don’t tamper
unnecessarily with controls or mechanisms and have a
qualified technician perform major repairs, replacements,
and seasonal maintenance.