Condenser Quick Stop/Start
#1
08-12-22, 01:45 PM
Condenser Quick Stop/Start
Had a new SpacePak indoor and outdoor unit installed to replace a failing 18yr old one. It's having some quirks and the HVAC company I'm working with hasn't been able to solve the problems.
The biggest issue I think is that the unit is hitting the coil freeze shutoff temp. I know that indicates bigger problems (likely oversized IMO)... but they have been so far unwilling to admit that. So I'm looking for solutions.
The issue:
* Cools fine for a while. But depending on indoor/outdoor temp, it will hit a coil temp of 34 degrees and display 'ANTIFROST FAULT' and shut off the condenser. Makes sense, I understand why.
* Once the condenser is off, the coil temp rises rapidly.
* About 18 seconds later, the coil temp hits 44 degrees and turns everything back on.
I'm concerned about the condenser quick-restarting like this. The unit is configurable for the freeze warning point, but is fixed for +10 degrees to re-enable the system.
Would it be worth installing a delay on break timer on the condenser line? Let it rest for 3-5 minutes before restarting? I'm obviously concerned about the longevity of the system if it's stopping and restarting often.
The biggest issue I think is that the unit is hitting the coil freeze shutoff temp. I know that indicates bigger problems (likely oversized IMO)... but they have been so far unwilling to admit that. So I'm looking for solutions.
The issue:
* Cools fine for a while. But depending on indoor/outdoor temp, it will hit a coil temp of 34 degrees and display 'ANTIFROST FAULT' and shut off the condenser. Makes sense, I understand why.
* Once the condenser is off, the coil temp rises rapidly.
* About 18 seconds later, the coil temp hits 44 degrees and turns everything back on.
I'm concerned about the condenser quick-restarting like this. The unit is configurable for the freeze warning point, but is fixed for +10 degrees to re-enable the system.
Would it be worth installing a delay on break timer on the condenser line? Let it rest for 3-5 minutes before restarting? I'm obviously concerned about the longevity of the system if it's stopping and restarting often.
#2
08-12-22, 02:23 PM
Group Moderator
Hmmmmm......
Does the same thing occur if you set the fan to max. ?
Post the model number.
There should be a system delay built in.
Does the same thing occur if you set the fan to max. ?
Post the model number.
There should be a system delay built in.
#3
08-13-22, 05:48 AM
The indoor unit is a SpacePak 3642 JH.
There is the 10 degree delay built in, but the coil temp rises quickly once the condenser shuts off.
Yes, I've played around with setting the fan between 80% and 100% and it doesn't seem to help.
It's a replacement from an old unit. We added a few extra vents to meet the newer requirements. The static pressure readings are within requirements, and the installer tested with the return completely open (checking to see if the return is too small and it's starving for airflow), but apparently that didn't change anything. But maybe I should re-check that myself (?)
There is the 10 degree delay built in, but the coil temp rises quickly once the condenser shuts off.
Yes, I've played around with setting the fan between 80% and 100% and it doesn't seem to help.
It's a replacement from an old unit. We added a few extra vents to meet the newer requirements. The static pressure readings are within requirements, and the installer tested with the return completely open (checking to see if the return is too small and it's starving for airflow), but apparently that didn't change anything. But maybe I should re-check that myself (?)
#4
08-13-22, 09:58 AM
Group Moderator
I can only think of an air flow problem.
An evap coil with no load will change temp like that.
The moving air usually keeps the temp from changing that fast.
An evap coil with no load will change temp like that.
The moving air usually keeps the temp from changing that fast.
