In my area the HVAC system comprises a natural gas fired furnace and an AC unit with the A-coil in the supply ducting. I test both in the summer. I have two questions.
Is it OK to test one right after the other, or do I have to wait a while. How long?
Why do they put the A-coil in the supply ducting and not the return ducting. If the pan overflows, it spills down onto the heat exchanger and blower motor.
You have better heat transfer between the air and the freon within the A-coil with the blower discharging against the coil rather than drawing the air thru the coil in the return although some are installed both ways.
Condensate is not suppose to overflow on to the heat exchanger if properly installed.
I personally do wait just a few minutes between testing heat and cool. Most units are equiped with a time delay between cool and heat. You will not damage any heat exchanger by suddenly changing the temp
Thanks for asking that question. I often wonder that myself. I have been waiting like 5 minutes just in case. Thanks for the answer Charley
For some reason, as you can see by the photo, the secondary (i.e. emergency) drain is never hooked up in my area. I suppose it’s because the furnace sits on the basement floor right beside the floor drain. Many times I’ve found the primary drain blocked and water pouring down through the furnace.
John all you can do is write it up you can not fix stupid the secondary is required for the very reason you stated in case the primary stoppes up.
Just do your job and report it you have no control over what the installer does
The coil is located in the supply (downstream from the furnace) because we do not want to make the heat exchanger cold as it will condense water inside of the heat exchanger and rust it out.
The A/C coil is 40F and the return air is in the 70’s.
40F is always below dew point, the return is not.
Makes sense. Thanks David and Charley.
I had that problem with the rusting heat exchanger at my house. Whoever installed the HVAC system apparently didn’t go to school for it, because that wasn’t the only thing wrong with it.
I ended up taking an HVAC training course and fixed it myself.
Thanks for that explanation.
So, when you find it installed the other way around, do you note it as a deficiency? Do you tell the buyer of the potential reduced life expectancy for the heat exchanger? Or do you just leave it alone?