Reduced hot water pressure after closing and reopening water supply in one upstairs tub

Question

A week ago, my dad had shut off the main water supply to our house to repair a leaky shower head. Upon opening water supply, our faucets sputtered for a little while as they normally do and water pressure returned to normal throughout the house. However, one of the tubs upstairs sputtered normally, and suddenly had very low water pressure on the hot side.

The water pressure is fine when set to cold, but it is immediately reduced when moving from warm to hot. No other faucet in the house is facing this issue. When switching from the tub faucet to the shower head, the water pressure has the same problem.

I inspected the faucet by removing the faucet handle, closing the hot and cold water supply on the faucet valve, and removing the cartridge. I am no plumber, but I didn't see anything that looked obviously broken. After putting everything back together, the hot water pressure did not change.

Could the escaping air from turning the water main back on have caused something to get lodged in the hot water supply for just this tub? Is there anything else I should check before I call a plumber?

Answer 1

Yes, there could be a connection between the two. In fact several things. Sometimes scale buildup (lime deposits) will occur especially in hard water areas. If the hot shutoff valve is old or your water is particularly hard you could have builup in the valve that is preventing full flow-through. Sometimes turning the main off and then on will loosen some of the scale resulting in a partial blockage. First make sure the shutoff is turned completely on. Turn the valve on and off a few times to loosen any debris. If it looks corroded I would replace it with a new quarter turn valve. The other trouble spot is in the cartridge which could be having the same issue. It could be either. There are some tests you could run to determine if the problem is the shutoff but without knowing your setup and your knowledge level I would suggest that you replace the cartridge and if that doesn't work, replace the shutoff valve - in that order.

Answer 2

I'd repeat what you did with the faucet but after removing the cartridge put a large bowl over the opening and then open the supply valve for the hot to flush out the pipe. See if it's the same flow as the cold. Then examine the cartridge and back feed some water through to flush out any debris. Also, many faucets have valve screens installed around where the supply valves on the faucet are... check to see if you have them and if you do, clean them out.