CSLB C-46 Solar ContractorSolar Thermal System InstallationEasy
A solar thermal installer is commissioning a new closed-loop glycol system. During the initial fill, the installer notices that the pump is running but the flow rate is significantly lower than expected, and there are gurgling noises in the piping. What is the most probable cause of this issue?
- AOversized expansion tank
- BAir binding in the system
- CInsufficient glycol concentration
- DDefective temperature sensor
Show answer & explanationAnswer & explanation
Correct answer: B. Air binding in the system
Gurgling noises, low flow, and a running pump are classic symptoms of air binding in a closed-loop system. Air pockets impede fluid circulation, reducing efficiency and potentially causing pump damage.
Why the other options are wrong
- A. An oversized expansion tank would not directly cause low flow or gurgling noises, though it might affect system pressure stability.
- C. Insufficient glycol concentration primarily affects freeze protection and heat transfer efficiency, not directly causing gurgling or low flow during initial fill.
- D. A defective temperature sensor would primarily impact control logic and system operation, not the physical flow rate or cause gurgling during initial fill.
Air Binding
The condition where air pockets trapped within a closed-loop plumbing system restrict or completely block the flow of fluid.
- Causes reduced flow and efficiency
- Often characterized by gurgling noises
- Requires proper venting during filling and operation
Memory trick: Low flow, gurgle, pump runs; air's the hidden, silent guns.