Here's an issue about forced-air heating/cooling that could be addressed with Keen Vents, but that Hubitat doesn't support.
I realize that the temp sensor built into the vents is "rubbish" according to Mike.Maxwell, but it can be used (at least with ST) to solve an annoying issue: when the thermostat decides to start heating, it will generally wait until the furnace firebox has warmed up before it starts the fan, but then blows cold air until the ductwork warms up.
The issue is that the ductwork has usually cooled down, and so for the first few minutes, the fan is blowing cold air into a room before heating it. I find this very annoying in my master bathroom, which I would prefer to keep warm and without cold drafts, particularly when the room is already cooler than the set temp.
On ST, I had this solved with simple RM rules, which said If the room temp (from Fibaro room temp sensor) is higher than the vent temp plus 5F, don't open the vent – but unfortunately the Hubitat driver for Keen Vents doesn't allow access to the value of the vent temp sensor. The vent temp sensor does not have to be accurate for this, just a repeatable indicator that heating is occurring and the vent is not yet as warm as the room.
Is there any Keen vent device driver which will run on Hubitat without errors, and which supports the Keen Vent temp sensor, so I could implement such a feature?
