Tankless Flush with recirculating pump

[danhome]

Hi All, I have a Nortiz tankless and im trying to do my first flush on the system. It's been on here when we bought the house.
There's also a hot water recirculating pump installed.
Does the recirculating pump make the flushing/descaling method any different?

I turned off both hot/cold shut off valves and connected the hoses to the isolation valves, but water kept coming out. Shouldn't there be no water movement since the shut off are closed? SO i thought maybe it had something to do with having a recirculating pump. I have no idea how this stuff works.

ANy help is appreciated. thanks!!
dan

 

[havasu]

What are you attempting to accomplish?

 

[danhome]

I'm trying to descale the tankless with vinegar.

 

[phishfood]

If it is installed in the manner that I am used to seeing, the recirc system should be installed before the isolation valves, and it should not cause you problems with backfeed at this point.

Can you post a picture of your water heater?