How To Choose A Water Heater: What Size Water Heater Do I Need?

14 / 02 / 2021

Tankless water heaters come in three different varieties: gas, electric or solar. On average, gas-fired heaters are cheaper to run and heat the water at a faster rate. However, they must include vents for gas dispersion and cost more to install. Electric heaters are incapable of heating up large volumes of water for use later, yet are easy to install. A basic rule of thumb to go by when choosing a water heater is that for one or two people, an electric heater will be adequate. For more than two people, a gas fired tankless heater is the best choice. We have prepared the following guide to give you some insight into how to choose the best water heater for your situation at home.

Calculate The Mounting Space

Tankless water heaters are much smaller than units which include a tank. This allows them to be wall mounted. Electric units can be mounted with very little space, however gas units require enough ventilation to disperse gas without harming anyone nearby. If space is not available for gas vents then an electric heater may be the only option available to you.

Register Your Water Temperature

Find out your cold water temperature with a thermometer. The temperature of the cold water will need to be heated to a degree suitable for boiling and cooking, so if your water is 40 degrees Celsius you will need a water heater that can heat your water by at least 60 degrees Celsius.

Determine Your Water Flow Rates

Tankless water heaters efficiency is determined by the water rates inside your home. Most appliances will have a GPM rating which describes how many gallons per minute a particular appliance will use.

Determine Your GPM Heating Capacity

Most gas fired tankless heaters cause a temperature rise of 39 degrees or more when 5GPM is used. Electric water heaters cause the same temperature rise, but for a lower GPM volume (1.5-2.5GPM). As a principle, the less water that is being used at any moment, the higher the water temperature that can be obtained.

Determine Your Tankless Water Heater Size

The size of your water tank determines how many GPM it can heat to a certain temperature. For example, a 200,000 BTU gas fired tankless unit is able to raise the temperature at a maximum of 39 degrees Celsius at 7.4GPM. Generally, for every GPM subtracted from this limit, an additional 10 degrees of heating is possible. So, to calculate the required BTU size of your water heater, you must register the maximum temperature required of your hottest appliance and its GPM requirement.

Contact NSW Hot Water Today For An Affordable Heating Solution

If you are in the market for a hot water unit, gas or electric, please contact NSW Hot Water today. We are open for trade 24 hours Monday to Saturday and can install hot water systems at any property in NSW. Please feel free to call and ask us any questions about sizing your hot water heater, our trained and certified team will be happy to help.