The incoming water temperature matters with tankless water heater performance because it directly affects the heating capacity of the unit. Tankless water heaters work by heating the water as it passes through a heat exchanger, which is typically powered by a gas burner or electric heating element. The colder the incoming water temperature, the more energy the unit needs to use to heat it up to the desired temperature.

During colder months, when the incoming water temperature is lower, the tankless water heater may struggle to reach the desired temperature or provide enough hot water for the household's needs.

However, there are a few things you can do to achieve higher temperatures during colder months:

1. Decrease or restrict the water flow rate: A lower flow rate through the heat exchanger can help increase the water temperature. However, you need to make sure that the unit can handle the decreased flow rate. Eccotemp tankless water heaters are equipped with built-in Over Temperature Sensors that will shut down the water heater if it gets too hot.

2. Insulate your hot water pipes: Insulating your hot water pipes can help reduce heat loss and ensure that the hot water reaches your faucets at a higher temperature. This can only be applied to permanently installed tankless water heaters and not our portable tankless water heaters.

3. Adjust the temperature setting; if you're not getting hot enough water, you can try increasing the temperature setting on the unit. However, you should be careful not to set the temperature too high, as this can be a safety hazard or trigger the over temperature sensor and shut down the tankless water heater.

4. Install a preheater: A preheater can be installed before the tankless water heater to raise the incoming water temperature before it enters the unit. This can help the unit perform better during colder months. But this can only be used for our electric tankless water heaters. It is not eligible for gas and propane tankless water heaters. Pre-heater units can be the Eccotemp EM-2.5, EM-4.0, EM-7.0, ESH-2.5 and ESH-4.0. Below is a picture of both the EM series and the ESH series.

5. Consider a larger unit: if your current tankless water heater is not providing enough hot water during colder months, you may want to consider upgrading to a larger unit that can handle the increased demand. For example, if you are using an i12-LP, which is rated at 4 GPM and you are using it for 5-6 fixtures or more, you will have to consider a much larger GPM tankless water heater like our Builders Grade series. Higher-rated GPM tankless water heaters can produce higher temperatures and perform better providing a good temperature rise even in colder environments or seasons.

It is important to note that these solutions may not be appropriate for every situation and case, and you should consult a professional plumber or HVAC technician to determine the best course of action for your specific needs. You can contact our product support as well through live chat on Eccotemp's official website, call us at 1-866-356-1992, or email us at [email protected].