Do wiser TRVs ever open the valve fully? I’ve run some experiments using a wiser TRV, a normal manual TRV and a few valves (including Drayton valves). These experiments were run with the valves not connected to any pipes, just on a table.
In all cases I’ve reset and recalibrated the iTRV before each test.
The result was that when the iTRV is at 100% demand (by setting the setpoint to 30C while the temp is 19) what happens is that the valve pin is only retracted 1-2mm instead of more than 4mm.
A normal manual TRV, when set to the highest setting causes the valve pin to retract 4mm (fully open).
It is interesting that during calibration after reset the iTRV motor does get fully up (pin fully retracted ) but at normal operation and 100% demand the pin opens much less.
Why would this happen, seems to be by design. I’m wondering if this is intentional or a bug. It surely must affect how fast the rad heats up at full demand.
Here’s some pictures of a Drayton valve with iTRV and manual TRV when ‘fully retracted’
On calibration: my understanding is that during calibration the motor extends as far as possible until it finds resistance (fulkyc closed) so it learns that eg 7mm extension are needed for fully closed.
What I am figuring out now is that it doesn’t really know where the fully open position is.
So what it does instead of retracting full when it needs to open fully is to retract just by 2mm from the fully closed position at most.