Hello, and thanks for your question!!
Is this a new problem or has it always been this way?
It has always been like this since we bought the house in December.
Ok, thanks, XXXXX XXXXX so I have a clear picture of the problem. I need to ask a few questions
Does the hot water seem to flow better to the fixtures closest to the water heater? Say that your in the shower in the shower farthest from the water heater, and then somebody turns the hot water on at a fixture closer to the water heater, is that when you loose hot water at the farthest shower?
I believe so. It hard to tell on the upper floor who is closer to the hot water as I don't know how the pipes run on the upper floor. I do know that if someone takes a bath in the master bath, there won't be any hot water in the master bath shower and it is the bath that the hot water runs to first.
The bath and shower in the master bathroom are separate.
The problem isn't the amount of hot water as much as it is the way they have the pipes laid out. How big is your house and are the bathrooms spread out pretty far? Where are the bathrooms located? (2 up and 2 down)?
The house is about 3700 square feet, one bath down, one bathroom in middle floor with no shower or bath, and two full bathrooms upstairs.
Ok, with a house that size and spread out that far I would have thought they would have installed a hot circulation pump or at least split up the hot water pipes. It sounds like the hot water pipes are in a long run. Do you know if you have a water circulation pump? It should be mounted by the water heater
Just a small box looking thing that's plumbed in to the hot water line and would be plugged into an outlet for power
There is no pump.
I think I did a pretty thorough check a few weeks ago.
I have seen them installed in the attic before, do you have an attic?
Yes. I have not checked there. We live a very cold climate. Most houses don't have utilities in the attic that I know of.
That was going to be my next question, thanks
Do you have any single handle fixtures?
All of them are.
You may also have a cross over issue. Single handled fixtures can actually start letting the hot and cold water mix in the pipes when the cartridges start going bad. Have ever noticed warm or hot water coming from the cold side when you turn the fixture on?
Thanks, XXXXX XXXXX like the hot water was just not plumbed right in your house. Is the water heater on the bottom floor?
ok, and is the water pressure good? If it is, does the water pressure change when the second shower is turned on?
The pressure seems to be OK. I don't notice a pressure drop when someone turns on water.
Thanks, XXXXX XXXXX sounds like you need a circulation pump or a second small water heater at the far end of the house. The water heater you have is a great size, but if not plumbed in right you will have the issue you have.
Can a circulation pump be installed without a dedicated return line?
I should say, can it be installed in existing piping that doesn't have a circulation pump.
Yes it can, but it would need a return line installed.That's why it would be easier to install an additional small water heater at the far end of the house.
Thanks for your help. I will have to look into the options.
your very welcome, I hope I was able to help answer your question
Thanks again for letting me assist you, If you have any follow up questions on this subject you can still reply back to me on this post and I will be happy to continue assisting you with it.