Just had a brand new Delta faucet installed. Water pressure was fine, but hot water dripped a little. Installer worked on it for a while and left showing us no leaks and good pressure. Now 1 week later cold water and spray hose work great, but hot water turned on full just trickles out of faucet and nothing from the spray hose. What can we do, other than call the contractor back for another service call?

What your p-lumber failed to do when he had the valve apart was to flush out any minerals he disturbed in the pipes and now they're clogging up the inlet ports of the cartridge. You can recall him on warranty or you can shut the water off and open up the valve. Pull the cartridge and check and clear the inlet port. Now turn the water back on for a moment to flush out the supply. Reassemble and test. Good luck, Tom

Would this problem only effect the hot water?