Forum Archive

My hot water heater has 6 temperature settings. Setting 1 is for being away (Low temperature setting used in the winter time, so the pipes don’t freeze). Settings 2-6 are different temperature settings (I’m not sure of the actually degrees). The default temperature setting for the water heater is setting 4 (right in the middle), which gives you 2 hotter (positions 5&6) and 2 cooler (positions 2&3) settings for the tank. I’ve moved the temperature setting to position 2. This still gives hot water for all morning and evening activities and I haven’t run into any issues of lukewarm or no hot water. For the sake of argument let’s say the temperature for each setting is as follows:

1 100 degrees
2 130 degrees
3 150 degrees
4 170 degrees Default
5 190 degrees
6 212 degrees

and my tank is 100 gallons. Now my question. 100 gallon tank at 130 degrees loses 30 gallons of hot water that is replaced by 30 gallons 60 degree cold water. Does it take more energy (gas heat) to reheat that 100 gallon tank back to 130 degrees? Or would it take less energy to reheat the 100 gallon tank if the tank was set to setting 4, 170 degrees or higher? I’m trying to figure out the correct setting that would maintain hot water using the least amount of energy. (Yeah it’s energy star compliant)Does it cost more energy to reheat the 130 degree tank becasue the overall temp of the tank dropped by 40 degrees(est.) vs 170 degree tank dropping 20 degrees(est)(due to the hotter 170 degree water heating the cold water faster then 130 degree water?) If this makes sense to you, and I hope it does, please reply I’ve been trying to figure this out for over a year. Thanks