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How to Choose Rinnai Tankless Water Heater


How to Choose Rinnai Tankless Water Heater


A tankless water heater unit has become the must have home appliance to every homeowner nowadays. Not because it lasts comparatively longer than traditional water heaters, it is almost maintenance free. In addition, a tankless water heater unit is easier to install as well. The only thing you need to ensure is- you have chosen the right sized one according to the demand of your household. Here is how to choose Rinnai Tankless Water Heater that can offer you an endless supply of hot water around the year. Let’s get started without delay!


Choose Your Mounting Space:

At first, you need to select the mounting space of your water heater. Mounting Space is the place in your home where you are planning to install the unit. As the word, “Tankless” suggests that the water heater unit doesn’t have any storage tank. Therefore, it won’t require much installing space. Besides, Rinnai Tankless Water Heater units are comparatively smaller in size comparing to other similar products. A 10” / 7” height/width is quite enough as mounting space. However, it’s your duty to select the mounting space before you proceed to buy a water heater unit.


Measure Cold Water Temperature:

The next thing you need to do is- measure the normal temperature of the cold water with a thermometer. You need to be very cautious at this stage, as the water heater will heat up the water to your expecting temperature. Also, make sure the unit you choose will be able to provide you with your desired temperature even when running at maximum flow rate.

Well, let’s give you a real life example. See; generally, people expect the warm shower temperature to be 104 F. Now, check the cold water temperature in your household. For example, the reading is- 60 F. At this position, you need a water heater that can heat up the incoming cold water up to 44 F to provide you 104 F at maximum flow rate.


Get to Know the Flow Rates:

Now, let us look at the following Water Flow chart so that you can determine the maximum amount of hot water supply you will need at a given time.


Let’s do a simple math now! From the chart, we come to know, a Shower requires 2.5 to 3 gallons of water per minute, and a Dishwasher requires 1.5 GMP. Now, if you need to use both Dishwasher and Shower at the same time, you will require 4 to 4.5 gallons of hot water supply per minute to run them simultaneously.


Calculate Your Rinnai Tankless Water Heater Size:

In order to calculate the size of your tankless water heater, you need to sum up Total GMP and your Desired Temperature. So, the math would be like,

Total GPM + Desired Temperature = the size of your Water Heater

Based on the suggested situation where the incoming cold water temperature in your household is- 60 F, and you need to run a Shower and a Dishwasher at the same time. Now, a shower requires 2.5 to 3 GMP, and a dishwasher requires 1.5 GMP while the maximum rise of temperature should be 110 F. So, you will need a water heater unit that can heat up the incoming water (60 F) up to 110 F at 4 to 4.5 GMP.


Now, it’s your turn to follow the steps as mentioned above and find out your required Rinnai Tankless Water Heater for the household. You can also talk to a professional plumber and ask him to do the measurement if you cannot manage yourself.