I've seen variations on this question, but the only times I've seen this exact question, the answers haven't been helpful... so thought I'd try here.

I've got a 66 gal. electric hot water tank, 10-15 years old, that feeds 3 full baths and a kitchen. One bath is in the finished basement, everything else is on the ground floor.

Get reasonably good hot water pressure / flow to every faucet / tub / shower EXCEPT the sink in the master bath. Have replaced everything back to the iron supply stub coming out of the wall, problem seems to be getting worse. Hooking a line directly to first the hot, then the cold supply stubs confirms that what's coming out of the wall is way weaker for the hot than the cold.

I'm thinking sediment (rust / calcium / ???) in these older pipes, probably at an elbow or tee... and that all my shutting off, turning on, attempting to flush that line have just caused more crap to move downstream to add to the blockage.

Is this the most likely cause?

If so... is there any trick I can use to break up or dissolve this unknown upstream blockage without tearing into the finished basement to try and hunt down the affected pipe?

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  • Hello, and welcome to Home Improvement. Interesting question, and good sleuthing; let's see if one of our experts can suggest something. – Daniel Griscom Mar 4 '19 at 2:43
  • If all efforts to clear the blockage fail I'd be looking at abandoning the existing pipe rather than locating and repairing it. Depending on the orientation of floor joists, air duct chases, etc there might be a way to route a new PEX tube with a minimum of access points cut through the wall coverings. A USD$20 USB bore scope camera may be valuable for assessing this possibility. – Greg Hill Mar 5 '19 at 4:01

If it is sediment, you could open only that problematic hot water tap at the sink, then shut off your water supply to the house and drain your water heater. That will suck all the hot water back down the line in the other direction and maybe flush out what is in there. that will at least be a way to narrow down if it is sediment within the line.

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    Could even go a step further and back-flush the hot supply line. Shunt cold to hot at that master bath sink, open the hot line "upstream" at the heater or other suitable place where the water and potential debris can be drained out, and let pressurized cold water flush backward through the hot piping. – Greg Hill Mar 5 '19 at 3:57

Sounds like galvanized pipe, this is a big problem. If you loosen the build up it can make leaks.

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  • Hello, and welcome to Home Improvement. Interesting idea; why do you think so? (A bit more info in your answers would be helpful.) Thanks. – Daniel Griscom Mar 5 '19 at 10:52

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