I blamed the washing machine because it was the appliance nearest the wet sock. Then I saw that the floor was dry beneath it and wet nearer the furnace. I moved the laundry basket upstairs and stopped guessing.
I stayed clear of the wet area around the equipment. Water near electrical parts needs care, not a hand reaching behind a cabinet. If reaching a control means stepping through water or touching wet equipment, leave it alone and get qualified help.
Several systems can share that corner
Source: Natural Resources Canada: heating and cooling maintenance
A high-efficiency furnace, cooling coil or condensate pump may produce or handle water in the same utility space. Nearby plumbing can leak too. NRCan includes condensate drain inspection in professional heating and cooling maintenance because blocked drains can cause damage.
From a dry, safe position, I noted which equipment had been operating and where I first saw water. I took a photograph showing the area rather than a close-up that hid the surroundings. I did not disconnect tubing, bypass a float switch or pour cleaner into a drain I had not identified.
Describe the timing
I told the service desk whether we were heating or cooling, whether a pump was making a new sound, and whether the wet patch was spreading. That gave them a useful starting point without pretending I had located the fault.
We followed the advice for safely stopping the affected equipment and protecting the room. The towels were for water already on an accessible floor, not a plan to keep running a leaking system indefinitely.
Later I labelled the equipment in our house folder using the installer's descriptions. Next time, I would be able to say which unit I meant. The washing machine had earned an apology, though it was unlikely to appreciate one.
