On Apr 2, 5:39*pm, DD_BobK wrote:
On Apr 2, 12:10*pm, Steve Turner
wrote:

A couple of months ago the heater quit coming on in my upstairs Trane XB80 HVAC
unit. *It's been off warranty for about 2 years, and I am enough of a
do-it-yourselfer that I'm comfortable with simple repairs. *I found that the
LED on the control board was not lighting up, and subsequently found that I was
not getting 24V output from the 115V-24V transformer. *Sure enough, the 24V
circuit was open, so I found a local replacement transformer (not the exact
form factor, but same specs) and things worked fine after I replaced it.. *Now,
I have the very same problem (only this time it's the A/C that's trying to come
on; not that it matters), and once again 24V is missing on the output side of
the transformer. *This time the 24V circuit has continuity, but the 115V
circuit is open. *Of course, I can replace the transformer AGAIN, but I'd sure
like to know what could be causing this problem... *Any ideas would be
appreciated. *Thanks.

Per other post...

And of

course lighting can cause surges to destroy things like this too. *

the problem may be on the supply side rather than the load side.

I would suggest a surge protector of some sort on the supply side.

and as others have suggested, *a better / continuos duty higher rating
transformer from Newark.

cheers
Bob

It would be pretty unusual for lightning to keep destroying the same
single
transformer in an HVAC unit without also detroying other things like
the
electronics board in the same furnace, or other appliances, eqpt, etc
in
the house. I've seen heard of lots of stuff inside a house getting
hit
by a surge, but never just a transformer, which should be among the
most surge immune devices, for a variety of physics based reasons.