Matthew Brinski wrote:Sorry about the latent reply, but I have been very busy -
Latent reply? Your reply is not at all hidden
Or are you giving off heat Taking the Mickey
Matthew Brinski wrote:It's not that simple, and I really don't care to convey my thoughts on why if it's going to be a "prove who's right" conversation..
Perhaps I was a bit testy in my post... perhaps you'll agree your's is completely off topic. Eric's is spot on.
"I believe that the position of the probe can have profound effects on the machine's behavior." is as obvious as "An electric espresso machine must be connected to an electrical outlet." If I said that, I'd expect a chorus of "DUH!" As an engineer, I often state the contrary and see if it makes sense "The position of the probe can have no effect." Following on, "I can place the probe on the counter and successfully control the boiler." As my physics prof said, "it's intuitively obvious" this is false and therefore the first is equally obvious.
Let's establish some givens:
- The PID is tuned and the boiler temp is stable at the set point.
- The boiler temp is adjusted so the user can walk up and pull a shot without the need to flush to reduce the group temperature.
- Shot interval is > 10 minutes.
And the obvious:
- Cold water injected into the HX causes a change in the boiler environment.
- There are no currents caused by physical water flow, only thermal eddies.
- These thermal eddies are not grossly different from idle boiler operation.
When I placed the probe in the boiler, these were the criteria :
- NOT above the heating element to reduce the likelyhood of over / under shoot
- CLOSE to the HX pipe for decent response to shot changes
- AWAY from the wall to minimize false change detection.
Some time in the future, I may see what happens with the probe in the steam area, not in the water at all.
Ken Fox has posted on water level and HX PID performance
Matthew Brinski wrote:I would imagine that the variances with an HX would have the potential to be more profound.
Have at it. I'm truly interested.