Do shut off valves reduce the flow of water?

I have a shower with a shut off valve for the hot water (but not for the cold water) and another shower without any shut off valves. The hot water in the former is not as hot as in the latter. FYI, the hot water / cold water mix is controlled by a single mixing valve in both showers. To control the mix, the mixing valve is turned from right (no water) to left (hottest).

Thank you!

It's not a valve that's causing it, it's the temperature limiting stop, behind the handle.

a regular type valve with a stem and washer has a wheel that turns does reduce flow.
a ball valve with a handle that only rotates 1/4 turn has little to no resistance depending on the size of the port..
anyway, I would suspect something else as the culprit before looking into the stop valve..
possibly a balancing spool/cartridge??

Dear NC Plumber,

Thank you for your prompt reply.

You said is "the temperature limiting stop, behind the handle." I didn't know there was one.

I assume that this applies only to showers with a single handle. Am I right? Intuitively, if there were two handles -a cold water handle and a hot water handle- there would be no temperature limiting stop. Right?

Thank you!

Dr. T



Edited 1 times.

Dear Packy,

Thank you for your prompt reply.

Is the "balancing spool/cartridge" the same as what NC Plumber called "the temperature limiting stop"?

Thank you!

Dr. T



Edited 1 times.

no. the limiting device stops the rotation of the handle at a set point so you can not get scalded.
a balancing spool/cartridge limits the flow of hot/cold mechanically so there will not be any sudden temperature changes.