The hot water pipe feeding the two is too small, either by build up inside the pipe (very common with steel lines), or because it was too small to begin with. Or a shutoff valve is partially closed (maybe at the hot water heater?)
The kitchen is probably closest to the water heater and the shower is the farthest. Water cools down the farther it travels through the pipes.
Stoppage
The plaming tubes are all conected.When the cold water run in kitchen the cold water at the shower become less,so with less cold water at the mix cold-hot (the balance is desterb),making the water hoter.Same if you turn on the hot in the kitchen the water will be colder in the shower.
it may be getting air in the system .
your vent on your shower or kitchen (if you have one) is not working and either the air from the water in the shower drain is carried down stream till it T's off to your kitchen sink then the air follows to your kitchen sink drain line backwards and to your kitchen sink trap and then bubbles through your trap because your water in your kitchen trap can not drain but the air has enough pressure to go through it OR your water from your shower is flowing past your kitchen drain T and making a siphon which causes air to go through your kitchen trap and makes the gurgling sound one way to fix the problem is to add a Vent line on your kitchen drain and your shower drain with in 42" on 1 1/2 or 60" on 2" on your trap arm if you want to follow the UPC code. Note to above Respondent: That little dot next to the question mark is a "period". Try throwing one in once in a while.
More "VOLUME" flowing from the tub spout then the shower head as the shower head has a flow restrictor
Because it effects the water pressure of the shower. This causes the temperature of the water in the shower to also change.
Shower is water that is sprayed over someone. Plumbing is the fixtures and piping that supplies water in a building. Shower plumbing would be the fixtures that spray water in a bathtub/shower stall.
Because someone is using water somewhere else. For instance, if you are having a shower and someone flushes the toilet, the water going to the shower is decreased because some is going to the toilet now.
Yes, remove your old shower valve and fit a new Moen anti-scald valve. This will not change when other items are turned on.
If you assume that the water entering your house in the mains pipe is at a constant pressure (this is a relatively good assumption) then the more outlets you give for it to flow from, the lower the flow rate from each one. Say you are supplied 1 litre per second and your shower is using all of this. Now, turn a tap on to 0.3 litres per second and there is 0.7 litres per second coming from the shower head. Showers are often upstairs and kitchens downstairs, so if the tap in question is in the kitchen then the effect will be greater than if they were both on level. The pressure of the water in the kitchen tap is made larger by the head of water pushing down from upstairs, and when both are turned on, the kitchen tap can "steal" more of the shower's water than a bathroom tap would when twisted the same amount.
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