How to replace a thermocouple on a Weil McLain gas
||If you did not turn the power off and you touch this roll out
switch to any metal part of the boiler it will spark and can cause
the transformer to but out. So make sure you turn the power off
||If you are replacing the thermocouple before it has failed you
will notice the pilot is still burning. This is a great opportunity
to test if the gas valve needs to be replaced. With the knob turned
to the pilot setting mentioned before.
||Take your 3/8" wrench and turn the thermocouple nut (the copper
one) to the left loosening the nut, this should cause the pilot to
go out. If you have removed the thermocouple nut from the gas valve
and the pilot stays on, The gas valve is defective and must be
replaced. Stop Turn the GAS COCK off and Call a professional.
||Most of the time the pilot goes out and that is what it is
designed to do. now that the pilot is out and there is no more flame
it is safe to remove the pilot tubing from the gas valve. in most
cases you will need to remove the burner to replace the thermocouple
and so you need to remove the pilot tubing from the gas valve as
well. use your 7/16" wrench to do this.
||Now to remove the burner, This type Weil McLain boiler has
simple aluminum burners that come out easy just grab the burner lift
so that the rear of the burner comes up then pull it forward to
clear the brass fitting it is resting on.
||be careful not to damage the pilot tubing when taking this
burner out sometimes it runs under the burner manifold and other
times it goes over. now you have the burner with the pilot assembly
in your hand.
||Removing the old thermocouple is easy it either will unscrew
from the bottom or just pull out, Just throw it away once you have
it out. because you have the pilot assembly in your hand it is a
good time to clean out the pilot orifice.
||Remove the 7/16" nut from the pilot assembly, being careful not
to bend it away from the burner, and also be careful not to drop and
lose the orifice it will be full of a white powdery substance clean
all that up and make sure the hole in the orifice is clear. be sure
to put it back and make the tubing connection tight when you are
||This is the orifice for this type of pilot assembly. they are
not all like this some need to be remover with a wrench this type
will come out just by removing the pilot tubing from under it.
||Your New thermocouple
comes with a little small piece of metal
and a threaded adaptor. some
applications require one or the other.
This type uses the threaded adaptor. If
the hole in the pilot assembly is to
small for the threaded adaptor, the
thermocouple just slides up into the
Website by: Thomas Petito Reardon