DIYbanter - View Single Post - AC Circuit Problem (voltage

Fred Bloggs

wrote:
The solenoid is normally on. I think it is part of a panic circuit that
is left over from the heat pump that we don't using any more. So far,
the best we have been able to figure out, the only time it is off is
when the thermostat is turned off. If the furnace is sitting idle it is
still active. From the wiring diagram, very crude and high level, it
shows that its operation is influenced by a flash detector, temperature
sensor (for over heating) and auxiliary input. Haven't determined if
the the aux is hooked up to anything.

What we have observed since I oroginally posted is this:

If the furnace, the circulator is running,

You're in upstate NY so a hydronic system would be typical.

the voltage at the solenoid
is about 24 volts but when it shuts down, it goes up to 28 volts. So
something else is putting a load on the same circuit to cause it to
drop.

Right- this is normal.

Our concern is for the solenoid being hot to the touch. Should we be
trying to change the voltage or the amperage to solenoid?

Derek

A few volts less is not going to make the solenoid run cool, it will
still be hot to the touch at its nominal rated voltage, it was designed
to run that way and the heat is normal unless the solenoid gets so hot
that it fumes and/or discolors- then it is defective in some way and
should be replaced. You could make an amperage check and verify that the
AC current through the coil is in the range of 0.75 +/-20% amperes just
to be sure. You say this is a dual cooling/heat system, so I assume the
solenoid valve is off when the thermostat is in COOL mode, meaning you
can't just remove it from the system.