In PID terms, this is even simpler yet - just a proportional controller. Only the error between the target and current position are acted upon by a single (proportional) gain:
(targetPosition.x - position.x)0.2 == ekP
A derivative term would be applied to the difference between the previous and current error, usually in order temper the rate of change. D terms can be a proper headache in practice, especially if you have any noise in your system...
Your point on HVAC companies not servicing homeowner-purchased systems is worth underlining.
In our case, we need some duct work to fit a 2-ton Mr. Cool system to our existing ducts. Every licensed HVAC contractor/company we've contacted has refused to touch any part of consumer purchased system, citing liability issues (context: Bay Area, CA).
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