A client complains that their bar sink faucet has very low hot water flow, while the cold water flow is normal. The building has a central hot water recirculating system. Upon inspection, you find that the aerator is clean and the isolation valves are fully open. What is the most likely cause of the reduced hot water flow?

Question: A client complains that their bar sink faucet has very low hot water flow, while the cold water flow is normal. The building has a central hot water recirculating system. Upon inspection, you find that the aerator is clean and the isolation valves are fully open. What is the most likely cause of the reduced hot water flow?

Answer options:

• A high-volume cold water supply line. ✅ A partially obstructed hot water supply tube or a clogged hot water port in the faucet cartridge.
• An incorrectly sized hot water heater.
• A leaky hot water shut-off valve.

Correct answer: A partially obstructed hot water supply tube or a clogged hot water port in the faucet cartridge.

Explanation: If only the hot water flow is affected while cold water is normal, and the aerator is clean, the issue is most likely localized to the hot water path within the faucet or its immediate supply tube. A partially obstructed hot water supply tube or a clogged hot water port in the faucet cartridge are common culprits. A leaky shut-off valve would cause a drip, not necessarily reduced flow, and hot water heater sizing wouldn't typically cause a localized low flow at one fixture exclusively if the recirculating system is otherwise functional.