replacing a circulation pump

[mzimmers]

Hi all -

I moved into a house with a recirc pump that I'm fairly sure was built in with the house (meaning the house has a return pipe for the hot water). I let it run dry and screwed up the motor, so today I replaced it. I'm attaching a pic because I want feedback from the smart people here on whether this looks like a reasonable install or not (both the original, and my fix; I'm pretty sure you can tell which is which; I replaced copper with PEX).

Questions:
1. the pump flows upward. So, why wasn't anything coming out of that pipe when the line was open?
2. it seems to be working, so do I really need that "comfort valve" that came with the system? Or is that mainly for retro-fits that don't have a dedicated return line?

Thanks...

 

[Diehard]

Did you have that water draw off spigot open long enough to allow the pump line to fill with water?
Being a centrifugal pump it needs water at the pump to pump.
In other words system has to be allowed to purge the air out.

 

[mzimmers]

Yes I did. As mentioned above, it seems to be working correctly. That so-called "sensor valve" appears to be the plumbing equivalent of a diode, and it doesn't seem that I need it (at least not to get the hot water when/where I want it).

I'm still not sure that I understand the circuit of the water. It would seem to me that the pipe coming out of the wall should spew water when the shut-off valve is open. But it didn't.

 

[Diehard]

Why do you say it seems to be working correctly if there is no signs of water passing thru to the discharge side?
The sensor valve is used to return back to the cold water inlet of the tank using the cold water feed at the fixture it is located. But it sounds like you have a separate hot water recirculation pipe based on your statement, "(meaning the house has a return pipe for the hot water)".

Are you sure you don't have a system which is using a sensor valve and using a cold water line?
Have you verified where that line with the pump is coming from?