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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I'm measuring the temperature (dry bulb and wet bulb) at the

Customer Question

I'm measuring the temperature (dry bulb and wet bulb) at the exit of the unit (Plenum) but the readings are inaccurate since the plenum it's not long enough. This means I'll have to measure it on the flex ducts. How can I open a test hole on the flex ducts without damaging it and also to be able to properly plug and seal it after taking the readings? Any tips on how to do this?
Submitted: 1 year ago.
Category: HVAC
Expert:  HVAC Mike replied 1 year ago.
This is Mike, I would try and get a measurement at the outlet of the flex duct, then compare it to the measurement you took at the plenum, this will actually show you if there is any heat gain thru the flex duct due to it being cracked or may have fallen off. I would not put a test hole in the flex duct, there also should be a starting collar off the plenum where the flex duct is attached, that is metal and you can drill a test hole in that, let me know if this helps you
Customer: replied 1 year ago.
thanks for the response! I will check and see if can drill a hole in the collar of the plenum for the flex duct
Expert:  HVAC Mike replied 1 year ago.
Your Welcome, If you need anything else answered i am here to help out anyway i can. also u can use silicone or they do sell 3/8 plugs to cover up the hole, u would need a 3/8 drill bit Thanks
Customer: replied 1 year ago.
Do you have any recommendations on the type of drill bit to use to open the test hole on the plenum?
Expert:  HVAC Mike replied 1 year ago.
Depending on the size of the probe you use is the size hole you could drill, use a bit for metal, i use a 3/8 bit because i have 3/8 plugs to cover hole when i am done, it looks more professional than a piece of duct tape over the hole, let me know if you need anything else, i am here to help you thanksMike