Here's a question............
If there's no way to pop a hole in the back of a residential furnace (walls or other restrictions) and evaporator coil is right above the furnace, is the limit hole (if centered) an option to take the TESP or is it still too much turbulence from the blower to get an accurate reading? I've never tried this myself.
Yes, I have used the limit hole on more than one occasion. Testing at that location, although not ideal(due to possible airflow turbulence), is better than not testing at all.
Instead of learning the tricks of the trade, learn the trade.
I recently stopped drilling and plugging holes in favor of using some cap tube in place of my static probes and just using the "factory installed holes" lol
Iv tested the variances between the two and as long as you hold the cap tube 90* to airflow the measurements are correct.
You can just remove a screw and place the cap tube in to take a measurement, easy peasy and no hole to plug.
Much quicker and easier to use once you learn to trust the readings after doing alot of testing and becoming familiar with it.
I use this for measuring SP on exhaust fans too since you cant drill type 1 hoods that carry grease through them.
As long as it can measure tenths of inches of WC, you're good to go. I use the fieldpiece manometer head with a dwyer 303 tip and a 1/4" bit. It has a switch to change the scale for anything above 1"(gas valves), and below 1"(static)