furnace static pressure

03steam13

I checked the static pressure on my furnace as it had never been checked. I drilled a 3/8" hole in the blower compartment door and a 3/8" hole between the furnace and the air conditioning coil. Using my dual port manometer, I placed the probe connected to the positive side of the manometer between the furnace and the coil and the negative side probe in the blower compartment door. My static pressure reading was 0.8"wc. This seemed a bit high. I checked the air flow performance chart in my furnace installation manual. The chart only goes up to 0.7"wc. I thought I might have an issue with insufficient return air so in the rec room in the basement I cut in a hole for a 16x16 return air grill. I re-checked the static pressure and it had dropped to 0.1"wc. What is an ideal static pressure reading for a 60k btu 90% efficient furnace? Should I leave it alone at 0.1 or reduce the size of the new return air opening to raise the static pressure up a bit. The furnace appears to be working fine and it is actually running quieter. Thanks in advance for any input.

pedmec

There is no ideal static pressure. Which is why you have a esp chart. if the chart does not list your static pressure then you have exceeded the manufacturers maximum allowable static pressure. This will also show up as exceeding the temperature rise of the furnace. Most furnaces have a temp rise between 35-65 but can vary from manufacturer.
Also remember that you can't take return air from the space the furnace is in. It's prohibitive by code and it doesn't make exceptions even if it's a 90 plus. At least for where i am from.

03steam13

Thank you for your reply. The furnace is in a separate room from the rec room. Since my reading is now on the chart I guess it's good. I will check the temp rise.

pecmsg

How to take TESP

https://youtu.be/6uMqw69XkRw