If you want to buy a tankless water heater for your home, there are several aspects you should look out for. You need to choose the type of the water heater, which usually means either electric tankless heater or gas tankless heater. More importantly, you need to know what you need the tankless heater for. It is very important to know if you need it for a single appliance, for a kitchen or a bathroom or for the entire home. That’s why I’m going to tell you what flow rates require the most common type of appliances and I’ll give you some examples of the temperature rise of some tankless water heaters.
It is very important that you know, approximately, what flow rates the appliances in your home need, because then you can calculate the total flow rate you need and at what temperature rise. A lavatory fixture type needs a flow rate of 0.5 gallons per minute.
The dishwasher should be provided with a flow rate of 1 to 3 gallons per minute. A shower requires a flow rate of 1.5 to 3 gallons per minute. The kitchen sink needs a flow rate somewhere between 1 gallon per minute and 1.5 gallons per minute. The pastry sink should have a flow rate of 1.5-2.5 gallons per minute. A laundry sink needs the flow rate to be somewhere between 2.5 and 3 gallons per minute. The appliance that requires the highest flow rate is the bathtub, the flow rate is required is between 2 and 4 gallons per minute. Another reason why the flow rates are important is because the tankless water heater can raise the temperature of the water based on the flow rate. That means if the flow rate is low, the temperature is high and if the flow rate is high, the temperature is low.
The flow rates of tankless water heaters depend on the type of tankless water heaters. The flow rate of a point of use tankless water heater is somewhere between 1 and 2 gallons per minute. Multiple appliance tankless water heaters can have a flow rate of 3 to 5 gallons per minute. The whole house tankless water heaters can reach a flow rate of 8 gallons per minute or even more. Knowing all these facts will make choosing a tankless water heater very easy. So, do all the calculations before you decide what tankless water heater you buy.