Phil-In-Mich. wrote:
OK, so I replaced the pressure release valve and maybe I broke the
pump in the process. I have a Lochinvar hot water boiler with a B&G
pump heating radiators.

About 10 to 12 years ago, I lived with a hot water heating system. Loved
it, but time moves on...

As I recall, there was a drain and fill event that I lived through,
and then a few hours after the system restart, one of the 5 pumps
wouldn't pump. See if this has anything like yours:

Between the B&G motor, and the actual pump there was a network of
springs and what not that connected the pump shaft to the motor
shaft. Memory going soft on me, but I seem to recall that after the
restart that spring assembly snapped. Was about a $12.00 replacement
part. And maybe 3 hours of cussing and fuming. Once I learned
(figured it out) how it all went together, may be a 12 or15 minute
job. (Right tools, right technology, right training, ....you do need
all three)
As I recall, I just went to a plumbing supply place that also listed
Hot Water Heating Systems parts as part of the store's inventory. Not all
plumbing supply houses carried Hot Water Heating parts. I
just described the spring thing, and they asked about the size of the
hot water pipe, and knew what the part was, and sold me what I needed.

Seems there could have been a large air bubble going thru the pump,
and this spring assembly goes busted. Don't know if by design or
safety feature to save either pump or motor. Generally, in 3D, the
shaft of the motor may not be in the exact alignment with pump shaft,
so spring assembly bridges the two shafts and transmit the power to
the pump.
As I said, may not apply to your case, and my memory is not as good
as it once was.

Phil

One of the problems with hot water boilers, is you MUST get ALL of the AIR
out. At the higher points in the piping, there should be a Hoffman Air
Vent. As the system is filled, air must be purged. Also, pumps are meant
to pump water, and if there's any air in the impeller, it won't pump well.
You must be sure all the air is out before starting.

--
Zyp