Suggestions for monitoring temp and airflow/pressure

signal15

Senior Member
This doesn't need to tie into anything. I just need a good, cheap way to monitor duct temperatures before and after my furnace, and possibly airflow. Is 1-wire probably my best bet?

I think there are some 1-wire static pressure sensors that I can use for this. Any recommendations on brands/places to purchase?

I am "tuning" my HVAC system. The builder installed the HRV and made the runs for it 60-80 feet long, which is a huge no-no. It's rated for 200cfm, but according to the manufacturer, I'm probably getting under 50cfm. Also, the room furthest from the furnace is not getting enough airflow. I've played with dampers and done a bunch of things, but I have no way to actually measure what is going on. I'd like to increase my fan speed, but I need to measure the current temperature increase to make sure I don't increase it beyond what it should be and end up with lukewarm air coming out of my ducts.

Also, I want to be able to measure the pressure in the basement, versus the pressure outside, and ensure that I have positive pressure in the basement to help with radon abatement.
 
Slighty OT..but the measuring above the fan/furnace is done to detect what?

My furnace has an internally wired sensor there already that shuts down the furnace if the temp gets too high or too low..presumably this is to avoid freezing ducts and overheating them i guess. I found this out because it turns out the trip level for heat was set way to low and for nearly a year my furnace ran only for short cycles heating up, tripping..cooling down..etc and it would take a long time for the temp in the house to raise. After it was adjusted the house heats up in probably half to 1/3 of the time compared to previously. I've noticed reduced propane usage too...
 
Oh, kinda the same reason I have a temp sensor on my cold water line coming into the house...it's just info. For me, the temp was helpful because it showed me that I could not run just the fan to circulate hot air in the house during winter. No matter how long I ran the fan, the temps above the stack never got into the 70's, so air coming out the registers was going to be even colder than that. That was a good lesson learned.

Also, having a heat pump, it's useful to know just how hot it gets on the coldest days (which is not very).
 
For A/C, isn't the air temperature drop across the coil one of the things technicians check to ensure the system is operating properly? If so, maybe having a temp probe in the return air duct immediately before it enters the "hardware" and another in the plenum box right after the hardware, and monitoring the difference in the two values, might give some indication of the efficiency/effectiveness of the A/C system.
 
Back
Top