Loss of pressure in hydronic radiant floor

[donnchadh]

Any idea why the pressure drops in my hydronic radiant floor when my Grundfos circulating pump is running, but the pressure returns to normal/stable when pump is off?

Because the pressure holds when the pump is off, logic says there is no leak in the system, but I am at a loss as to why the pressure drops steadily when the pump is on. Could it be due to the simple fact that the pressure gauge itself is placed on a faucet; at a dead end, so to speak? The faucet is used to bleed air from the system.

Thanks in advance for any help, and if you couldn't tell from my post, I am a complete novice.

[havasu]

I'm just guessing, but wouldn't that mean the pump is going out?

[waterwelldude]

The pressure is not actually dropping. It is the flow/movement of the water that is causing the gauge to appearer to lose pressure. The gauge is just bouncing so to speak.

[donnchadh]

Thanks for the help.