Tankless Hot Water Heater

05 Oct. 20

Determining the Size of a Tankless Hot Water Heater

There are two types of  tankless hot water heaters: gas or electric. Tankless Water Heaters are, on average, more efficient and heat water faster than appliances. However, it must be ventilated and incur higher acquisition and setup costs. The deciding factor is that an electric flow heater is sufficient for one or two people. For more than two people, the gas tankless heating solution is the solution.

Determine the Mounting Space

Tankless water heaters are smaller than storage tanks so that they can be wall-mounted. Electric unit sizes range from 10 ” to 7,” and gas unit sizes from 30 “to 20”. Electric companies can be installed in a minimal space, but gas units must have enough room for installation and play to emit combustion fumes. If your device does not have a workstation or vents, you can only select an electrical device.

Measure your Cold Water Temperature of Tankless Hot Water Heater

Check the temperature of the cold water with a thermometer. The temperature of the water is the starting point. This water is heated to the desired temperature by the tankless device and must maintain the desired temperature at maximum flow. For example, hot water in the kitchen sink is generally desirable at a temperature of 110 ° F. When the cold water flow is 50 ° F, the water heater should raise the water temperature. See below 60 degrees at the inlet at full discharge to keep the cooking water at 110 F.

Determine your Water Flow Rates


The flow of the water determines the efficiency of a water heater through your home. A low-flow showerhead can use 1.5 gallons of hot water per minute, or GPM as it is also called. When washing dishes, the sink can go through the tap 1.5 points per hour, and the working bath can use four cubic millimeters. Many devices have a GPM rating. For example, the manufacturer’s or dishwasher’s label indicates the GPM rating of the device. If you can’t get a base GPM size, for example: on a bathroom faucet, for example, place a gallon container under the faucet and note the time it takes to fill it. If one glass can be served in 20 seconds, it makes three glasses in 1 minute or 3 times 1 for the GPM level.

GPM Heating Basics

Most tankless gas water heaters heat up to 70 F or more when using 5 GPM of water. Most electric tankless devices cause a similar 70-degree rise in temperature. However, this happens when a maximum of 1.5 to 2 GPM of water is used. The less water you use at the same time, the higher the water temperature.


Determine your Tankless Hot Water Heater Size

Start with the inlet water temperature, which in this example is 50 F. Set the maximum flow rate in gallons during use. For example, a person showers 1.5 hours per hour, and the desired temperature is 105 F. The person washes 1.5 hours per hour, and the desired temperature is 110 F. The washing machine also runs at 2 GPM, and the average wash temperature is 120 F. The total annual limit for this period is 5 GPM. To maintain the water temperature required for all of these functions simultaneously, you will need a water heater that raises the water temperature to 70ºF at 5 RPM.

This can be done with a multi-gas water heater. However, they are scored based on the maximum amount of GPM given temperature rise. For example, 200,000 BTUs without a tank can raise the total water temperature to 50 F up to a maximum of 7.4 GPM. Usually, each drawn water pipe raises the water temperature by 10 degrees. In this case, a 200,000 BTU water heater can heat all the water in the house to 110 F at a rate of 6.4 GPM. Since only one washing machine is required for this temperature, a 200,000 BTU unheated water heater is required for this cable.

To know more contact Best quality Plumbing.