Grainfather

[peebee]

It's not the pump! The pump is most likely fine (as was determined by @Tombo in #5 and #7). @RoomWithABrew hinted at the more likely problem. The pumps are okay, but under-powered. The merest hint of blockage and they stop (stop pumping that is, the motor still runs but the "magnetic coupling" slips).

Replace the poxy tap and coupler at the top of the return pipe and all is fine again. I replaced the filter too, but that probably isn't necessary.

This was me going through a similar battle with the final cure (which didn't involve buying another pump, or selling the "broken" perfectly "good" pump). Warning, off site link: Backup Pump? "Jim's Beer Kit"

 

[Tombo]

It's not the pump! The pump is most likely fine (as was determined by @Tombo in #5 and #7). @RoomWithABrew hinted at the more likely problem. The pumps are okay, but under-powered. The merest hint of blockage and they stop (stop pumping that is, the motor still runs but the "magnetic coupling" slips).

Replace the poxy tap and coupler at the top of the return pipe and all is fine again. I replaced the filter too, but that probably isn't necessary.

This was me going through a similar battle with the final cure (which didn't involve buying another pump, or selling the "broken" perfectly "good" pump). Warning, off site link: Backup Pump? "Jim's Beer Kit"

I think mine was most definitely down to the pump, I had stripped it down and everything was clear and free running but it wouldn't even pump clear hot water.
To solve it I decided to work backwards, the pump worked fine when cold but not when it got hot. That suggested that something was expanding with heat somewhere. So I brought some water up to boiling point so that the pump stopped working. I then removed the screws on the impeller, switched the pump on and carefully rotated the impeller housing around the pump body. What I found was that it only worked in one position and even then only if more pressure was applied on one side than the other. I put a thin little shim between the plastic impeller housing and the pump body to compensate for the misalignment and re-tightened the screws and all is now working perfectly again (at least for the time being).

 

[Agentgonzo]

Good to know peebee. I've not had any problems with my GF, but I've not done the hundreds of brews that some people have. I do a pretty thorough clean of everything, but hadn't thought of taking apart and fully cleaning the recirc disconnect and tap. I don't think it's necessary for me to completely replace it, but it is good to know I should do a thorough clean of it every few brews from now on

 

[peebee]

... I do a pretty thorough clean of everything, but hadn't thought of taking apart and fully cleaning the recirc disconnect and tap. ...

Grainfather are aware of the problem (I found out later). But they've "fixed it" by offering a fairly costly upgrade: GRAINFATHER RECIRCULATION ARM & CHILLER CAMLOCK UPGRADE. Doesn't upgrade tap.

[EDIT: And tap it can still be! I tried the common fix of removing the spring and ball from the coupler (safety auto-shutoff), but the restrictive tap still clogged up.]

 

[peebee]

... I think mine was most definitely down to the pump ...

Glad you sorted it! Not come across that issue, but it is further evidence that those GF pumps are under-powered. They work, but with very little built-in tolerance before not working!

 

[Agentgonzo]

Grainfather are aware of the problem (I found out later). But they've "fixed it" by offering a fairly costly upgrade: GRAINFATHER RECIRCULATION ARM & CHILLER CAMLOCK UPGRADE. Doesn't upgrade tap.

[EDIT: And tap it can still be! I tried the common fix of removing the spring and ball from the coupler (safety auto-shutoff), but the restrictive tap still clogged up.]

by tap, are you referring to the red flow valve/lever?

 

[peebee]

by tap, are you referring to the red flow valve/lever?

Yes.