I have 2 bathrooms. When I shower in the bathroom farthest from the water heater and someone uses water elsewhere the water turns hot or cold depending on what is being used. How could I solve this problem?
You may want to consider installing a new shower valve. Most new valves have a temperature control such as Moen’s Posi-temp valves which maintain a plus or minus 3 degree temperature variance. Water temperature will always vary depending on a host of factors. If one’s hot water heater is not running properly, then there can be temperature differentials. Sometimes there can be problems with the age of the hot water heater and as time goes by, sediments can collect and the energy efficiency and output can be adversely impacted. Also, one can run into a problem with the thermostat not functioning properly and replacement may be required. Anytime one is running a competing appliance, such as a washer or even a dishwasher, warm water flow and pressure can be impacted and this can cause the temperature to fluctuate if you were concurrently taking a shower.
I do think that your shower valve need to be upgraded with one that has a temperature control. That will not only correct the problem you are encountering, it will also allow you the flexibility of setting the temperature where both comfort and efficiency meet. It would also serve as a good time to educate your family on the importance of matters such as water conservation and prudent use of the shower. Anytime one can take measure to make the appliances in one’s home more efficient and they can become more aware of conservation issues, then it saves you money in the pocketbook.
Finally, if you have not had your main plumbing and heating and conditioning systems inspected for seasonal maintenance, then this would be a good time to get that done to nip in the bud any problems you may have.