Will increasing water pressure make it heat up faster?

If I turn the hot water faucet or shower knob on just a teeeeensy bit, will it get hotter slower than if I turn it on all the way? Or will the water heat up at the same rate as long as the faucet is turned on at all?
Thanks guys! You’re so helpful :slight_smile:

It will depend on what you are heating the water with. My heater heats ‘on demand’ so the faster the water runs, the cooler it is. If I want to warm the bath up, I run the hot tap just fast enough to light the gas - it is scalding hot then.

If you have a hot water cylinder, it makes no difference - once the hot water is gone it’s gone. Of course, the hot water is being replaced with cold, so it will get tepid eventually, but I doubt that the heater element works fast enough to make any difference.

The pipe between your hot water heater and your faucet will cool down to room temperature. This is a specific volume that must pass through the faucet until the hot water gets there. How long this takes is completely dependent on the rate of flow. So in your OP, the first is correct, you will get hot water faster by opening up the faucet more.

As said it depends on the system. Long before the modern on demand systems, my parents had a hot water coil in the boiler (furnace). This boiler would be both for hot water and the hot water radiator system to heat the house. If you wanted a really hot shower you would close the hot water valve a bit to allow the water to pass slower through the hot water coil, so it would heat up more. On full blast the water was only mildly hot.

To get the hot water to the faucet however when you first start running the water usually full pressure is best, then it can be turned down once the hot water arrives.

The time the water spends in the piping system also comes into play, but unless it’s a very long run, travel though large uninsulated spaces, and/or a very slow flow it wouldn’t matter much as the hot water will heat the pipe.

I think the OP makes it clear that the question concerns the delay in initially receiving hot water.

So watchwolf’s answer is correct: the cool water in the pipe between the water heater and the tap must be cleared, and the time that takes will be inversely proportional to the flow rate.