Quote Originally Posted by Bordo11 View Post
Using Infinity 58MVB60 air handler installed the static pressure showed by Infinity thermostat display is 0.9 1.0. It seems a bit high.
The air duct (supplies) sizes I have calculated for the 600 700 CFM by using well know HVAC Calc software tool.

I removed the air filter insert from an air purifier GAPA body, keeping the filter compartment open letting easier for the air to get into the air handler.
I was surprised that the static pressure went up by 0.1

It is an old house and the ducts installation was a real pain.
But I want to get the pressure down to appropriate 0.5 level or so.

My question is should I add more returns or more supplies?
Are we to assume that you installed this system yourself?

If you didn't, then you should be calling the installing contractor back if you have concerns about the TSP the control is showing.

Either way you've just found out first hand one of the first basic rules of air flow in ductwork. Velocity increases static pressure.