Hot water pressure drops when flushing toilets

Old 01-05-06, 12:35 PM
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Hot water pressure drops when flushing toilets


About 2 weeks ago, I disconnected my dishwasher as part of my kitchen remodel project. As part of disconnecting my dishwasher, I first shut off the water main right out side of my house; replaced the kitchen cold water connector (used to have 2 outlets: one for sink and one for dishwasher; now I put in a temporaray one with just one sink outlet); also turned off the hot water heater because I did not know how long it would take me to do the task.

When I turned on the hot water heater and the water main out side my house, we began to experience low hot water pressure every time when a toilet is flushed. If one of us is in the shower when a toilet is flushed, the hot water will be completely gone. If we are washing hands in a sink when a toilet is flushed, the hot water becomes a small trickle. This never happens before I took out the dishwasher.

Did I not turn on the hot water heater in full? Do I have a pressure change in the system anywhere since? What did I do to have caused this?
Old 01-05-06, 02:21 PM
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What may have happened is the cold water supply valve did not open all the way when you turned the WH back on. Now this is dependent on IF you shut the valve off when you were working on the water system. If it is a gate valve (round handle on top of valve) the gate may have dropped partially. To check this, you will have to shut the main water off again and remove the valve bonnet. Bonnet is the top of the valve body. It could also be that debris clogged either the inlet or outlet nipple of the WH. Since the pressure drops when another fixtures cold water is turned on, I would guess that it is the cold inlet nipple or the inlet valve. Good luck.

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