how does one know when a circ pump is repairable or junk?

[topofthehil]

I went through three taco 007 pumps already this year.
don't know why... wish I did.
the last one that went out was a zoning pump that feed my plenum HE. the water temp going into the HE is about 85^F.
the temp coming from the HE was 83^F. a heat gun on the pump motor was running 146^F.
if only the cartage is shot, I can rebuild the pump.
if the motor is shot, I assume so is the pump?
how do I know if the cartage is shot or if indeed the motor is shot.
how hot should the pump motor get?
why would these pumps be gong out after only 3 years and running for 6 months each year?
is there any troubleshooting that I can do?
any suggestions would be greatly appreciated.
topo

 

[Pat53]

I went through three taco 007 pumps already this year.
don't know why... wish I did.
the last one that went out was a zoning pump that feed my plenum HE. the water temp going into the HE is about 85^F.
the temp coming from the HE was 83^F. a heat gun on the pump motor was running 146^F.
if only the cartage is shot, I can rebuild the pump.
if the motor is shot, I assume so is the pump?
how do I know if the cartage is shot or if indeed the motor is shot.
how hot should the pump motor get?
why would these pumps be gong out after only 3 years and running for 6 months each year?
is there any troubleshooting that I can do?
any suggestions would be greatly appreciated.
topo

hard to say why they are failing, but they have a 3 year warranty from time of purchase. I would call Taco support and see what they say.

 

[DaveBP]

Are they all mounted with the motor shaft horizontally?

 

[topofthehil]

some pumps are horizontal mount and some are not.
I think two of the three were vertical mount and one horizontal mount.
I thought I read that if the pump sees over 20 psi that it can be mounted vertically?
and, this manifold is being supplied by a 011 circ pump that, according to my temp/pressure gauge, is a little over 20 psi.