There has always been a delay in getting hot water in kitchen sink (approx. 1 min). Now when running the tub upstairs (2 story home) the water does not get hot at all. The water in the sink in that bathroom takes approximately 1 minute to get hot. Please help.. cold showers for guests are no fun. Thank you.

Can you give us the brand name of your valve? One handle or two knobs? Back to you, Tom