A call came through that a customer was experiencing a cold floor, but the HUG Hydronics In-floor Heating System was turned on and looked like it was working. I was sent out to investigate.
I discovered, upon examination, that pump 10 only had a zone jumper for zone 1, when zones 2,3, and 4 were the ones currently employed. So I added those jumpers and retired for the evening.
The next morning the customer called again. His floor was still cold! I, Hughlock Holms, was too focused on the clues I had been presented with to thoroughly examine what was going on and missed the fact that pump 10 was only running at low speed, and it wasn't pushing enough warm water into the tank for the other pumps to push into the floor loops.
I quickly changed out that pump with pump 1, and both worked. I surmise something must have been stuck in the pump and dislodged when I handled it. Nevertheless, the customer will be getting a brand new pump that he can exchange out if a pump decides to fail again.