The water gets a little warmer when the thermostat for house heat is turned up which is odd. I replaced the spindle inside my shower control but still the same. Suggestions please.
Your post is a little confusing. Are you referring to water pressure? Or water Tempature? Or both? There are so many things it could be. What you stated is very odd. Did you replace all the items inside the diverter? Have you always had the same water pressure at the sink and the shower on both hot and cold? What type of pipe is feeding the shower? Is it large enough? What is the temp of the water at the water heater that feeds that bathroom? What is the temp and pressure at the sink in the bathroom? Does the pipe feed both the sink and the shower from a tee? Do you have a pressure regulator at the source? Do you have a back flow preventor at the source? How far is this bathroom away from the water heater? What size pipe is feeding this bathroom?
As I stated, there are many thing that could be causing this. If you can answer the questions that I have posted, maybe we can figure out the issue, and suggest a solution.
Handy Andy In Mt Airy NC
Ok sorry. I'm talking about the temperature . Hot water at all other sinks but not enough to shower. It's warm enough sometimes but doesn't always last. If wanted a hot shower can't take one. It's Fed by 1/2" copper coming from tankless system. Shower on 2nd floor and obviously boiler in bsmt. Hope I answered all the questions.
How long of time do you have hot water at all the other sinks? Especially the sink in that same bathroom. If it is approx 20-30 minutes, then the water heater is not the issue. I would bet it is with the mixing valve in the middle of the shower valves. Either something is clogging the hot side, or the mixing valve itself is beginning to fail. Cheap valves use rubber instead of ceramic, and the rubber will deteriorate quicker than ceramic or brass. If there was a tank water heater replaced recently, that would answer the question about the debris. Or if there was galvanized pipe that was recently replaced, that would answer the question about the debris. I would look more at the mixing value that controls the shower valves.
You mention both tankless and a boiler. Those are two distinct methods of heating water.