What Causes a Shower to Run Hot When You Flush a Toilet? | Day And Night Air | Day and Night Air

Your Phoenix home’s plumbing has a lot in common with a tree; it has a main trunk, or supply line. Like a tree, pipes branch off from that trunk to supply fixtures with water. This is why you get parboiled when a family member flushes a toilet – your shower and toilet are served by the same branch line, and cold water pressure drops when the toilet’s supply valve demands more cold water. Ouch!

Hot or Cold

Your shower also can get mighty cold mighty quickly when an appliance that uses hot water – such as the dishwasher or clothes washer – suddenly diverts hot water from the trunk line, away from your shower. This, too, can be painful.

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You have several options to avoiding the pain of a too-hot or too-cold shower:

  • Ask family members not to flush when the shower is running
  • Avoid running the dishwasher (or clothes washer) and shower at the same time
  • Slightly reduce supply line pressure to the toilet by turning the supply-line valve clockwise; your toilet will take longer to fill up, but you will not feel quite so hot when it does

Two Better Ideas

Of course, Day & Night Air, your Phoenix plumbing company with expertise in solving homeowner headaches, can provide expert solutions beyond changing routine behavior. Why settle for assigned times for the dishwasher, shower or clothes washer?

1. Thermostatic Mixing Valve

No matter the water pressure, this will maintain the precise temperature you desire. A drop in cold-water pressure is immediately answered by a drop in hot-water pressure.

2. Load Balancing Manifold

This simple piece of pipe effectively severs the trunk and all the branches, replacing it with individual lines for each load (like your shower). Pressure cannot drop because the main trunk is fed directly by the hot water supply out of your water heater. This manifold immediately divides into the seven (or more lines) needed by sinks and washers throughout your home. A kitchen sink, clothes washer, dishwasher and two-and-a-half baths only would require eight hot-water lines. Each fixture gets its own hot-water line directly from the manifold. No pressure drops, scalding or shivering in the shower!

Contact Day & Night Air to learn how you can hire a plumber to make your Phoenix home more livable and your showers more enjoyable.