What Temperature Should I set my Tankless water heater at?
What Temperature should I set my tankless hot water heater to?
My Navien NR-240A is currently set to 125 degrees. My previous tank water heater showed a temperature of 119 degrees (F). Two questions should arise here:
1) Does it cost more to set my tankless water heater at a higher temperature?
2) Why should I set my tankless water heater temperature to be higher than my former tank water heater?
Answer to 1: The amount of gas consumed to set the temperature of your tankless water heater higher is negligible. Unlike a tank water heater, your tankless heater does not consume gas when water is not in demand. Put another way, your tankless heater doesn't continuously burn gas to heat your water even hotter than it was before. A large portion of your hot water is used in showers and baths (depending on your usage and equipment). As most people do not like showers or baths at 125 degrees (f), most will turn down the hot tap and turn up the cold tap to get the blend of water that generates the temperature required. For a tankless heater, this means that there is a smaller draw of hot water at 125 degrees and a larger draw of cold water. Since the draw of hot water is reduced, the amount of gas to heat the smaller flow is also reduced.
For washing dishes or laundry, the higher temperature will cost you more money as the temperature may not be offset with cold water. However, because it takes a bit of time to get hot water to these devices in the first place, you may find that the water temperature isn't as hot as you might expect.
As for me, I keep my tank at 125 degrees (F) because if I am in a bath, and the water has gotten colder than I like, I want to be able to add hot water to warm the tub again, and if the incoming hot water is a quite a bit hotter than the standard 120 degrees (F), then it will heat the current bath water faster.
Bear in mind that the hotter you set the hot water temperature, it poses the risk of burning/scalding.
25-Jan-2012 - I increased the temperature by 5 degrees to 130F. Sometimes e.g. dishes, the water just didn't seem hot enough. It does now though even though the change is a small one...