The Tagaki is likely to fire for 30 seconds to get the water temp up to
120F and then shutoff while you continue to circulate the water.
After 30 to 90 seconds of circulation, the water temp has dropped low
enough that the Tagaki will fire again. Remember the Tagaki detects
BOTH flow and temperature of its outlet water.

....

You will use ALOT of gas to do this, even though Tagaki does document
the application in their guide.

That's exactly the type of info I was looking for. Thanks! I though
it may work like that, but needed confirmation.