My grundfos up15-10b5/tlc will not open the check valve right after pump

Copy following links:
http://waterheatertimer.org/Water-heater-recirculation-system.html
http://waterheatertimer.org/Crossover.html
http://waterheatertimer.org/images/IMG_9325-grundfos-timer-800.jpg

1) Bad check valve ... take apart and clean with white vinegar
2) Bad single handle faucet cartridge ... test for cross connection
3) Set timer operation instead of thermostat operation ... thermostat operation may be bad depending on location of thermostat

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Replace crossover valve located under sink
http://waterheatertimer.org/Water-heater-recirculation-system.html
http://www.amazon.com/dp/B00128BIUU/?tag=waterheaterti-20

gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Pump can be bad or clogged with debris loosened when pipes were moved.
Check installation, and check if crossover valve is installed correctly
Check if single-handled faucets are good
http://waterheatertimer.org/Water-heater-recirculation-system.html
http://waterheatertimer.org/Crossover.html

Gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Sounds like 2 problems:
1) Crossover and 2) Setting timer
Recirculation system has check valve that stops backflow of water when pump is turned off.
When check valve is clogged with sediment, or has worn out, then cold water enters hot pipe or hot water enters cold pipe when faucet is turned on.
Take apart connection where grundfos connects to both hot and cold pipes, and clean with white vinegar or CLR.
http://waterheatertimer.org/Crossover.html
http://waterheatertimer.org/Water-heater-recirculation-system.html

Open following link for setting typical FM/1 analog timer module on Grundfos recirculation pump:
Your timer module may vary in appearance.
Slide switch selector might be located below timer dial.
http://waterheatertimer.org/images/IMG_9325-grundfos-timer-800.jpg

Open following link to view how recirculation system looks:
http://waterheatertimer.org/Water-heater-recirculation-system.html

Ordinarily the cold water line is used to complete recirculation loop.
There is no reason why you cannot run separate line back to water heater instead of using cold water line.
The Grundfos system comes with crossover piece that connects hot-and-cold lines at furthest faucet.
Instead of connecting between hot-and-cold line, simply connect hot to your new hot water return line.

When your new line arrives back at water heater, it must connect to cold water inlet so return water is directed to bottom of water heater.
For critical safety concerns, do not remove TP valve to install new water inlet.
Nor is it best to use extra plug on top of tank to install new water inlet, unless you also install dip tube that directs water to bottom of tank.
http://waterheatertimer.org/How-it-works.html
In the case of tankless water heater, return line must be connected to cold water inlet also.

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It sounds like the installation loosened sediment inside pipe.
Remove sink aerator and see if you can flush open the faucet.

Also check if other faucets are receiving hot water from hot-and-cold taps that says if grundfos is pumping hot water from the water heater correctly.
http://waterheatertimer.org/Water-heater-recirculation-system.html

When recirculation pump is running, both hot and cold water lines have hot water.
If other faucets have hot water in both lines, then that tells you the blockage is localized in furthest faucet supply lines.
You may have to dissemble those supply lines and flush the sediment out.

Turn on the hot water at the farthest faucet from the water heater. Once hot water is at that sink immediately go check other taps in the home. If you have to wait more then 10 seconds for hot water at other taps then you have a branched system.

If it is starting and stopping, it most likely does have some type of leak. The check vavlve is normally installed on the suction side of the pump, and sometimes instead of a check vavlve or in addition to, there is a foot valve. A foot valve is just a check valve (usually with a screen) at the end of the line in the bottom of the cistern. If you have much suction lift, and the check valve leaks (or any leak in the suction piping) then the water will drop back into the cistern. This will also cause the discharge side of the pump system to drop in pressure, causing the pump to restart. You mentioned removeing the pressure tank, that tank keeps the pump from short cycling when you have low demand on the system. If the pump is higher than the cistern, and you don't see a check valve between cistern and pump then you most likely have a foot vavle in the cistern. Hopefully it's accessable by removing the pipe.

It will probably be cheaper to purchase another pump

Yep! That is the problem with this type system!

To fix the problem run a third pipe from where the pump is back to tee into the cold input of the HW tank. Insulate this third line.

It will be more efficient as well.